Datasheet
7.5V to 18V, 6A Integrated MOSFET
1ch Synchronous Buck DC/DC Converter
BD95861MUV
●Description
BD95861MUV is a 1ch synchronous buck converter that
can generate output voltage (0.8V to 5.5V) at the input
voltage range (7.5V to 18V). Space-saving and high
efficient switching regulator can be achieved due to
built-in N-MOSFET power transistors. The IC also
incorporates H3RegTM technology, a Rohm proprietary
constant ON TIME control mode which facilitates
ultra-high transient response against changes in load
without external compensation components. Fixed soft
start function, power good function, and short circuit /
over voltage protection with timer latch functions are
incorporated. The BD95861MUV is designed for power
supplies for Digital AV Equipment.
●Features
・Input Voltage Range:
7.5V to 18.0V
・Reference Voltage
0.8V±1.5%
・Output Voltage Range:
0.8V to 5.5V
・Output Current:
6.0A (Max.)
・Switching Frequency:
350kHz to 800kHz
（depend on input-output condition）
・Built-in Power MOS FET
High-side Nch FET ON resistance:
50mΩ(typ.)
Low-side Nch FET ON resistance:
30mΩ(typ.)
・Fast Transient Responses due to H3Reg control
・Over Current Protection (OCP) – Cycle-by-Cycle
・Thermal Shut Down (TSD)
・Under-Voltage Lock-Out (UVLO)
・Short Circuit Protection (SCP)
・Over Voltage Protection (OVP)
・Fixed Soft Start (1msec ; typ)
・Power Good function
●Applications
・LCD TVs
・Set Top Boxes (STB)
・DVD/Blu-ray players/recorders
・Broadband Network and Communication Interface
・Amusement, other.
●Package
・VQFN024V4040
●Pin Configuration (TOP VIEW)
●Typical Application
2
17
Thermal Pad
3
16
4
15
5
14
6
13
21
20
19
18 PGOOD
PGOOD
VIN
2
17 EN
VIN
3
16 BOOT
VIN
4
15 SW
PGND
5
14 SW
PGND
6
13 SW
PGOOD
EN
EN
BOOT
SW
SW
SW
VOUT
9
10
11
12
SW
SW
SW
SW
SW
PGND
PGND
PGND
8
Figure.2 Pin Configuration
Figure.1 Typical Application Circuit
○Product structure：Silicon monolithic integrated circuit
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© 2012 ROHM Co., Ltd. All rights reserved.
TSZ22111・14・001
7
SW
12
PGND
11
22
PGND
10
23
1
PGND
9
VOUT
18
8
24
VIN
19
1
7
FB
PGND
GND
PGND
VREG
PGND
TEST
VIN
20
VIN
VIN
21
VOUT
VIN
22
FB
VIN
23
GND
VIN
VREG
VIN
TEST
24
W(Typ.) x D(Typ.) x H(Max.)
4.0mm x 4.0mm x 1.0mm
○This product is not designed protection against radioactive rays.
1/23
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BD95861MUV
●Block Diagram
24
VREG
VIN
22
VIN
VREG
Thermal
Protection
TSD
1
｜
4
5V
5VReg
VOUT
BOOT
19
EN/UVLO
TSD/SCP
EN
UVLO
TSD
REF
SS
R
H3RegTM
Controller
Block
SS
FB
Q
Driver
Circuit
S
SW
OCP
+
+
-
OVP
SCP
UVLO
OCP
SCP
TSD
PGOOD
18
Power
Good
10 SW
｜
15
VREG
Soft
Start
20
BG
BG
16
SCP
5 PGND
｜
9
EN
BG
0.56V
+
-
SCP
EN
17
FB
Delay
REF
Reference
Block
UVLO
0.96V
+
-
OVP
FB
EN
21
23
GND
TEST
Figure.3 Block Diagram
●Pin Description
No.
Symbol
Description
1-4, 24
VIN
Input Voltage Supply pin.
The IC determines the duty cycles internally based on the input voltage. Therefore, variations of VIN pin can
lead to unstable operation. This pin also acts as the input voltage to the internal switching regulator output
block, and is sensitive to the impedance of the power supply.
Connect over 10uF ceramic capacitors for the decoupling capacitors to PGND as near as these pins.
5-9
PGND
10-15
SW
16
BOOT
17
EN
Enable Input pin.
When the input voltage of the EN pin reaches at least 2.2V, the switching regulator becomes
active. At the voltage less than 0.3 V, the IC becomes standby mode.
18
PGOOD
Open-drain Power Good Output pin.
Due to the open-drain output, a 100kΩ pull-up resistor should be connected between this pin and
VREG or other power supply. In the case of no use, this pin is opened or shortened to ground.
Power ground pin connected to the source of the Low side FET.
Switch node connection between High side FET source and Low side FET drain.
Connect 0.1μF capacitor and 20Ω resistor between BOOT and SW. This pin is also connected
to inductor (L).
High side FET Gate Driver Power Supply pin.
Connect 0.1μF capacitor and 20Ω resistor between BOOT and SW.
BOOT voltage swings from VREG to (VIN + VREG) during normal switching operation.
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BD95861MUV
●Pin Description (Continued)
No.
Symbol
Description
19
VOUT
20
FB
21
GND
22
VREG
Power supply output inside IC. When at least 2.2V is supplied to the EN pin, the VREG is active.
This pin supplies 5.0V at up to 10mA. Insert a 4.7μF capacitor between this pin and ground pin.
23
TEST
TEST Pin. Connect to ground.
Thermal
Pad
-
Output Voltage Sense pin.
Connect to output voltage directly. ON TIME is determined by monitoring the output voltage.
Output Voltage Feedback pin. FB is compared with REF in the IC. Please set the output voltage
in the feedback resistances of less than total 50kΩ. (Refer to page 15)
Sense ground pin for all internal analog and digital power supplies.
Exposed Thermal Pad. Connect to ground.
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BD95861MUV
●Absolute Maximum Ratings (Ta=25℃)
Parameter
Symbol
Limit
Input Voltage
VIN
20 *1
V
BOOT Voltage
BOOT
27 *1
V
BOOT-SW
7 *1
V
VOUT
7 *1
V
SW Voltage
SW
20*1
V
Output Feedback Voltage
FB
VREG
V
BOOT-SW Voltage
Output Voltage
VREG Voltage
VREG
7
Comment
Unit
*1
V
EN Input Voltage
EN
20 *1
V
PGOOD Voltage
PGOOD
7 *1
V
Power Dissipation 1
Pd1
0.34
W
Ta≧25°C (IC only), power dissipated at
2.72mW / °C.
Power Dissipation 2
Pd2
0.70
W
Ta ≧ 25°C
(70mm×70mm×1.6mm
single-layer board, 6.28mm2 copper heat
dissipation pad), power dissipated at
5.6mW / °C.
Power Dissipation 3
Pd3
2.20
W
Ta≧25°C (70mm×70mm×1.6mm 4-layer
board, 6.28 mm2 copper heat dissipation
pad on top and bottom layer, 5505 mm2
pad on 2nd and 3rd layer), power dissipated
at 17.6mW / °C.
Power Dissipation 4
Pd4
3.55
W
Ta≧25°C (70mm×70mm×1.6mm 4-layer
board, all layers with 5505 mm2 copper
heat dissipation pads), power dissipated at
28.4mW / °C.
Operating Temperature Range
Topr
-20～+100 *1
℃
Storage Temperature Range
Tstg
-55～+150
℃
Tjmax
+150
℃
Junction Temperature
*1
Not to exceed Pd.
●Operating Ratings (Ta= -20 to 100℃)
Parameter
Symbol
Limit
Unit
Min
Typ
Max
VIN
7.5
12
18
V
VREG Voltage
VREG
4.5
5.0
5.5
V
BOOT Voltage
BOOT
4.5
-
23.5
V
SW
-0.7
-
18
V
BOOT-SW
4.5
-
5.5
V
EN
0
-
18
V
Output Voltage
VOUT *2
0.8
-
5.5
V
PGOOD Voltage
PGOOD
0
-
5.5
V
Minimum ON Time
Tonmin
-
-
200
nsec
Input Voltage
SW Voltage
BOOT-SW Voltage
EN Input Voltage
*2 VOUT depends on Input Voltage (VIN) in some cases.
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BD95861MUV
●Electrical Characteristics
(Unless otherwise noted Ta=25℃, VIN=12V, EN=3V, VOUT=3.3V)
Parameter
Symbol
Limit
Unit
Condition
Min
Typ
Max
IIN
-
1.2
2.0
mA
IIN_STB
-
2
15
A
EN Low Voltage
ENLOW
GND
-
0.3
V
EN High Voltage
ENHIGH
2.2
-
18
V
EN Bias Current
IEN
-
3
10
A
EN=3V
VREG_STB
-
-
0.1
V
EN=0V
VREG Output Voltage
VREG
4.5
5.0
5.5
V
IREG=10mA
Maximum Output Current
IREG
10
-
-
mA
High side FET ON Resistance
RONH
-
50
100
mΩ
Low side FET ON Resistance
RONL
-
30
60
mΩ
FB threshold Voltage
VFB
0.788
0.800
0.812
V
FB Input Current
IFB
-1
-
1
A
TON
-
470
-
nsec
TOFFMIN
200
450
-
nsec
Soft Start Time
TSOFT
-
1.0
-
msec
VOUT Discharge Current
IVOUT
3
6.6
-
mA
VIN Bias Current
VIN Standby Current
EN=0V
Enable Control
VREG Output Voltage
VREG Standby Voltage
Power MOSFET
Reference Voltage
H3Reg Control
ON Time
Minimum OFF Time
Soft Start / Output Discharge
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VOUT=1V, EN=0V, VREG=5V
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BD95861MUV
●Electrical Characteristics (Continued)
(Unless otherwise noted Ta=25℃, VIN=12V, EN=3V, VOUT=3.3V)
Parameter
Symbol
Limit
Unit
Condition
Min
Typ
Max
IOCP
6.1
10.5
-
A
*3
SCP Threshold Voltage
VSCP
0.48
0.56
0.64
V
VFB=0.8V → 0V
SCP delay time
TSCP
-
1.0
-
msec
OVP Threshold Voltage
VOVP
0.86
0.96
1.06
V
OVP delay time
TOVP
-
1.0
-
msec
VREG Threshold Voltage
VREG_UVLO
3.75
4.20
4.65
V
VREG Hysteresis Voltage
dVREG_UVLO
100
160
220
mV
VFB Power Good Low Voltage
VFB_PL
0.61
0.68
0.75
V
VFB=0.8V → 0V
VFB Power Good High Voltage
VFB_PH
0.65
0.72
0.79
V
VFB=0V → 0.8V
Over Current Protection
Over Current Protection
Current Limit
SCP
OVP
VFB=0.8V → 2.0V
UVLO
VREG: Sweep up
VREG: Sweep down
Power Good
＊3
No tested on outgoing inspection.
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●Typical Performance Curves (Unless otherwise noted
Ta=25℃, VIN=12V)
100
100
90
80
80
VOUT = 3.3V
60
50
VOUT = 5.0V
60
Tc [ ℃]
Efficiency [%]
70
VOUT = 1.2V
40
40
30
20
20
10
0
0
0
2
4
6
0
1
2
3
4
5
6
Iout [A]
Iout [A]
Figure.5 Tc – Iout
(VIN=12V, VOUT=3.3V, L=2.2μH)
Figure.4 Efficiency
(VIN=12V, L=2.2μH)
SW
5V/div
SW
5V/div
VOUT
(AC)
20mV/div
VOUT
(AC)
20mV/div
1μsec/div
Figure.6 VOUT Ripple voltage
(VIN=12V, VOUT=3.3V, L=2.2μH, COUT=44μF, Iout=0A)
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1μsec/div
Figure.7 VOUT Ripple voltage
(VIN=12V, VOUT=3.3V, L=2.2μH, COUT=44μF, Iout=6A)
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BD95861MUV
Ta=25℃, VIN=12V) (Continued)
3.38
3.38
3.35
3.35
3.33
3.33
VOUT [V]
VOUT [V]
●Typical Performance Curves (Unless otherwise noted
3.30
Iout=0A
3.30
Iout=6A
3.28
3.28
3.25
3.25
1
2
3
4
5
8
6
12
14
16
VIN[V]
Figure.8 VOUT Load Regulation
(VIN=12V, VOUT=3.3V, L=2.2μH)
Figure.9 VOUT Line Regulation
(VOUT=3.3V, L=2.2μH, Iout=0A)
3.38
750
3.35
700
3.33
3.30
600
550
3.25
500
0
20
40
60
80
8
100
10
12
14
16
Temperature [℃]
VIN [V]
Figure.10 VOUT - Temperature
(VIN=12V, VOUT=3.3V, L=2.2μH, Iout=0A)
Figure.11 Frequency - VIN
(VIN=12V, VOUT=3.3V, L=2.2μH, Iout=0A)
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18
650
3.28
-20
10
Iout [A]
Frequency [kHz]
VOUT [V]
0
18
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BD95861MUV
●Typical Performance Curves (Unless otherwise noted
Ta=25℃, VIN=12V) (Continued)
EN
5V/div
EN
5V/div
SW
10V/div
SW
10V/div
VOUT
2V/div
VOUT
2V/div
PGOOD
5V/div
PGOOD
5V/div
200μsec/div
Figure.12 Start up with EN
(VIN=12V, VOUT=3.3V, L=2.2μH, COUT=44μF, Iout=0A)
2msec/div
Figure.13 Power down with EN
(VIN=12V, VOUT=3.3V, L=2.2μH, COUT=44μF, Iout=0A)
VOUT
2V/div
VOUT (AC)
50mV/div
SW
10V/div
Iout
2A/div
IL
5A/div
200μsec/div
100μsec/div
Figure.14 VOUT Transient Response
(VIN=12V, VOUT=3.3V, L=2.2μH, COUT=44μF)
Iout=0⇔2A (SR=1.0A/usec)
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TSZ22111・15・001
Figure.15 OCP function
(VIN=12V, VOUT=3.3V, L=2.2μH, COUT=44μF)
(VOUT is shorted to ground)
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BD95861MUV
●Explanation of Operation
The BD95861MUV is a 1ch synchronous buck converter incorporating ROHM’s proprietary H3RegTM CONTROLLA system.
When VOUT drops due to a rapid load change, the system quickly restores VOUT by increasing the frequency.
1. H3RegTM System
1-1. Normal Operation
When FB falls below the threshold voltage (REF), a drop is detected, activating the H3RegTM CONTROLLA system.
Ton =
VOUT 1
VIN
f
[sec]
(1)
HG (Gate of High side MOSFET) output is determined by the formula (1). LG (Gate of Low side MOSFET) output operates
until FB voltage falls below REF voltage after HG becomes OFF. OFF time is restricted by MIN OFF Time (typ.:450nsec).
Hence, BD95861MUV runs with a constant on time by using the input and output voltage to set the internal on time timer.
1-2. VOUT drops due to a rapid load change
When FB (VOUT) drops due to a rapid load change and the voltage remains below REF, the system quickly restores
VOUT by shortening OFF time of HG (increasing the frequency), improving transient response as shown Fig. 16 (b).
FB
FB
REF
REF
HG
Io
LG
HG
LG
(a) Normal operation
(b) Rapid load change
Figure.16 H3REG System
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BD95861MUV
●Timing Chart
1. Soft Start Function
Soft start is utilized when the EN pin is set high. Current control takes effect at startup, enabling a moderate “ramping start”
on the output voltage. Soft start time is 1.0msec (typ). Rush current is determined via formula (2) below.
IIN =
C OUT VOUT
1.0msec
[A]
(2)
COUT: All capacitors connected with VOUT
EN
1.0msec (typ)
FB
VOUT
IIN
Figure.17 Soft Start Timing Chart
2. Power Good Function
When FB voltage is more than 0.72V (90%), the integrated open-drain NMOS is set to OFF, and PGOOD outputs High due
to pull-up register. If FB voltage falls below 0.68V (85%), PGOOD becomes Low.
EN
0.72V
0.68V
FB
PGOOD
Figure.18 Power Good Timing Chart
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●Protection Operation
1. OCP Operation
Normally, when FB voltage falls below REF voltage, HG becomes high. However, if the current through the inductor (IL)
exceeds OCP current value (IOCP) during LG=ON, HG does not become high and IL is restricted by IOCP. When IL falls down
below IOCP, HG is stricken by the pulse width of Ton decided by formula (1). As the result, the output voltage can decrease
as the frequency and duty are changed.
When OCP is released in the state that the output has decreased by OCP operation, the output voltage might rise up due
to high-speed load response. Also OFF Latch is operated when FB voltage becomes below the SCP setting voltage during
1msec (typ.) (Refer to 2-1).
Iocp (10.5A : typ)
IL
FB
REF
SW
HG does not become High until IL falls
down IOCP, even if FB < REF.
Figure.19 OCP Timing Chart
2. SCP Operation / OVP Operation (OFF Latch)
2-1. SCP Operation
SCP monitors FB voltage. When FB falls below 0.56V, after 1msec (typ.) later, the short circuit protection (SCP) operates,
turning the high side MOSFET and low side MOSFET OFF, and performs OFF latch operation.
2-2. OVP Operation
OVP monitors FB voltage. When FB exceeds 0.96V, after 1msec (typ.) later, the output over voltage protection (OVP)
operates, turning the high side FET OFF and the low side FET ON, and performs OFF latch operation.
2-3. Recovery from OFF Latch mode
Off latch is released by EN=OFF or UVLO operation, and then it returns to standard operation.
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BD95861MUV
.
FB < REF Switching frequency become faster
HG
LG
0.56V
1msec(typ)
FB
SS
VREG
EN
Latch Release
by EN or UVLO
Normal Operation
SCP
OFF Latch
Normal Operation
Stand by
Figure.20 SCP Timing Chart
FB > REF, HG=L
HG
LG=H
LG
0.96V
FB
1msec(typ)
SS
VREG
EN
Latch Release
by EN or UVLO
Normal Operation
OVP
OFF Latch
Normal Operation
Stand by
Figure.21 OVP Timing Chart
3. TSD Operation (Self Recovery)
TSD is self-activating. If the junction temperature exceeds Tj = 175℃, and HG, LG, PGOOD, and SS become Low.
The IC becomes standby when TSD operating.
When Tj falls below 150℃, it returns to standard operation.
4. UVLO Operation
UVLO operates when VREG voltage falls below 4.05V(VIN=6.05V(typ.)), ad HG, LG, PGOOD and SS become Low.
The IC becomes standby when UVLO operating.
UVLO is released when VREG goes up to 4.2V(VIN=6.1V(typ.)), and starts standard operation
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BD95861MUV
●Selection of Components Externally Connected
1. Output LC Filter Selection (Buck Converter)
1-1. Inductor (L) Selection
The Output LC filter is required to supply constant current to the output load. A larger value inductance at this filter results
in less inductor ripple current (∆IL) and less output ripple voltage. However, the larger value inductors tend to have less
fast load transient-response, a larger physical size, a lower saturation current and higher series resistance. A smaller
value inductance has almost opposite characteristics above.
The recommended inductor values are shown in Table 1(Refer to page 18).
The value of ΔIL is shown as formula (3).
ΔIL =
(VIN
− VOUT ) VOUT
L f VIN
[A]
(3)
For example, with VIN = 12 V, VOUT = 3.3 V, L = 2.2H and the switching frequency f = 600 kHz, the calculated ripple
current ⊿IL is 1.8A.
Then, the inductor saturation current must be larger than the sum of the maximum output current (IOUTMAX) and 1/2 of
the inductor ripple current (∆IL / 2). A larger current than the inductor’s saturation current will cause magnetic saturation in
the inductor, and decrease efficiency. When selecting an inductor, be sure to allow enough margins to assure that peak
current does not exceed the inductor’s saturation current value.
※To minimize loss of inductor and improve efficiency, choose a inductor with a low resistance (DCR, ACR).
VIN
I
HG
IL
L
Inductor saturation current > IOUTMAX +⊿IL /2
VOUT
SW
⊿IL
L
COUT
LG
Average inductor current
(Output Current：IOUT)
t
Figure.22 Inductor Ripple Current
1-2. Output Capacitor (COUT) Selection
Output Capacitor (COUT) has a considerable influence on output voltage regulation due to a rapid load change and
smoothing output ripple voltage. Determine the capacitor by considering the value of capacity, the equivalent series
resistance, and equivalent series inductance. Also, make sure the capacitor’s voltage rating is high enough for the set
output voltage (including ripple).
Output ripple voltage is determined as in formula (4) below.
ΔVOUT=ΔIL/(8×COUT×f)+ESR×ΔIL +ESL×ΔIL / Ton
[V]
(4)
(ΔIL Output ripple current、ESR: Equivalent series resistance、ESL: Equivalent series inductance)
Also, give consideration to the conditions in formula (5) below for output capacitance, bearing in mind that output rise
time must be established within the fixed soft start time. As output capacitance, bypass capacitor will be also connected
to output load side (CEXT, Fig.23). Please set the over current detection value with regards to these capacitance.
COUT
1msec (IOCP − IOUT )
VOUT
[F]
(5)
(IOCP : OCP Current Limit, IOUT : Output Current)
Note: an improper output capacitor may cause startup malfunctions.
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BD95861MUV
VIN
HG
VOUT
SW
L
ESR
Load
LG
CEXT
ESL
COUT
Figure.23 Output Capacitor
2. Input Capacitor (CIN) Selection
In order to prevent transient spikes in voltage, the input capacitor should have a low
enough ESR resistance to fully support a large ripple current. The formula for ripple
current IRMS is given in equation (6) as below.
VIN
CIN
HG
VOUT
SW
L
VOUT (VIN − VOUT )
IRMS = IOUT
[A]
VIN
COUT
LG
Where VIN =2×VOUT, IRMS=
(6)
IOUT
2
A low ESR capacitor is recommended to reduce ESR loss and improve efficiency.
Figure.24 Input Capacitor
3. Output Voltage Setting
The IC controls output voltage as REF≒VFB.
However, the actual output voltage will also reflect the average ripple voltage value.
The output voltage is set with a resistor divider from the output node to the FB pin. The formula for output voltage is given
in (7) below:
Output Voltage =
R1+R2
R2
× REF +ΔVOUT
REF = VFB(TYP 0.8V) + 0.02 – (ON DUTY × 0.05)
[V]
(7)
[V]
(8)
VOUT
ON DUTY =
(9)
VIN
Please refer to eq. (4) regarding ΔVOUT.
VIN
REF
H3RegTM
CONTROLLA
R
Output Voltage
VOUT
Q
Driver
Circuit
S
VFB
R1
R2
Figure.25 Output Voltage Setting
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BD95861MUV
Set ON DUTY in less than maximum ON DUTY
shown in Fig26.(DCR of inductor : 0.05Ω)
This data is the characteristic value, so it’ doesn’t
guarantee the operation range.
Max ON Duty : VOUT / VIN
0.7
0.6
0.5
0.4
0
1
2
3
4
5
6
Iout [A]
Figure.26 Max On Duty in each output current
4. Relationship between Output Voltage and ON TIME
BD95861MUV is a synchronous buck converter controlling constant ON TIME. The ON TIME (Ton) depends on the output
voltage settings, as described by the formula (10).
Ton = 1770
VOUT 610
−
+ 55
VIN
VIN
[nsec]
(10)
The frequency of the application condition is determined by the formula (11) using the above Ton.
Frequency =
VOUT
×
1
[kHz]
(11)
VIN
Ton
However with actual applications, there exists a rising and falling time of the SW due to the gate capacitance of the
integrated MOSFET and the switching speed, which may vary the above parameters. Therefore please also verify those
parameters experimentally.
5. Relationship between Output Current and Frequency
BD95861MUV is a constant on time type of switching regulator. When the output current increases, the switching loss of
the inductor, MOSFET, and output capacitor also increases. Hence the switching frequency speeds up.
The loss of the inductor, MOSFET, and output capacitor is determined as below.
① Loss of Inductor = IOUT2 × DCR
VOUT
VIN
VOUT
× (1 VIN
② Loss of MOSFET (High Side) = IOUT2 × RONH ×
③ Loss of MOSFET (Low Side) = IOUT2 × RONL
)
④ Loss of Output Capacitor = IOUT2 × ESR
(DCR : Inductor Equivalent series resistance、RONH : On resistance of High-side MOSFET、RONL : On resistance of Low-side MOSFET、
ESR :COUT Equivalent series resistance)
Taking the above losses into the frequency equation, then T (=1/Freq) becomes
VIN × IOUT × Ton
T (=1/Freq) =
[nsec]
(12)
VOUT × IOUT + ① + ② + ③ + ④
However since the parasitic resistance of the PCB layout pattern exists in actual applications and affects the parameter,
please also verify experimentally.
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BD95861MUV
●PCB Layout Guide
Two high pulsing current flowing loops exist in the buck regulator system.
The first loop, when FET is ON, starts from the input capacitors, to the VIN terminal, to the SW terminal, to the inductor, to
the output capacitors, and then returns to the input capacitor through GND.
The second loop, when FET is OFF, starts from the low FET, to the inductor, to the output capacitor, and then returns to the
low FET through GND.
To reduce the noise and improve the efficiency, please minimize these two loop area.
Especially input capacitor and output capacitor should be connected to GND (PGND) plain.
PCB Layout may affect the thermal performance, noise and efficiency greatly. So please take extra care when designing
PCB Layout patterns.
L
VIN
CIN
FET
VOUT
COUT
Figure.27 Current loop Buck regulator system
・The thermal Pad on the back side of IC has the great thermal conduction to the chip. So using the GND plain as broad and
wide as possible can help thermal dissipation. And a lot of thermal via for helping the spread of heat to the different layer
is also effective.
・The input capacitors should be connected to PGND as close as possible to the VIN terminal.
・The inductor and the output capacitors should be placed close to SW pin as much as possible.
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BD95861MUV
●List of Evaluation Board Circuit
C6
C1
VIN
C2
PGND
PGND
21
20
VOUT
VIN
22
FB
VIN
VIN
23
PGOOD
19
1
18
2
17
Thermal Pad
3
16
4
15
5
14
6
13
7
8
9
10
R2
R3
GND
VIN
VREG
TEST
VIN
24
R4
11
PGOOD
R5
VREG
EN
EN
BOOT
R1
SW
C5
SW
L1
SW
VOUT
C3
12
C4
SW
SW
SW
PGND
PGND
PGND
Figure.28 Typical Application Circuit
Table 1. Recommended BOM List(VIN=12V)
Symbol
C1,2
C3,4
C5
C6
R1
R2
R3
R4
R5
Part
Capacitor
Capacitor
Capacitor
Capacitor
Resistance
Resistance
Resistance
Resistance
Resistance
Value
10μF (25V)
22μF (16V)
0.1μF(50V)
4.7μF (16V)
20Ω
※
※
※
100kΩ
L1
Coil
※
SW1
※
VOUT
1.0V
1.2V
1.8V
3.3V
5.0V
R2
130Ω
220Ω
110Ω
1.5kΩ
680Ω
Manufacture
Murata
Murata
Murata
Murata
ROHM
ROHM
ROHM
ROHM
ROHM
TDK
ALPS
R3
360Ω
2kΩ
5.6kΩ
13kΩ
24kΩ
Series
GRM31CR71E16KA12
GRM31CB31C226ME15
GRM18 Series
GRM31 Series
MCR03 Series
MCR03 Series
MCR03 Series
MCR03 Series
MCR03 Series
SPM6530 Series
GLMC Series
2 point switch
R4
2.2kΩ
4.7kΩ
4.7kΩ
4.7kΩ
4.7kΩ
L1
1.5μH
1.5μH
2.2μH
2.2μH
2.2μH
The above components list is an example. Please check actual circuit characteristics on the application carefully before use.
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TSZ22111・15・001
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TSZ02201-0F3F0AC00130-1-2
24.Mar.2022 Rev.006
BD95861MUV
●I/O Equivalence circuit
VIN
VIN
SW
BOOT
BOOT
VIN
BOOT
SW
SW
VREG
EN
SW
PGOOD
EN
PGOOD
VREG
VOUT
VOUT
167k
833k
FB
VREG
VIN
BOOT
FB
VREG
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24.Mar.2022 Rev.006
BD95861MUV
●Operational Notes
(1) Absolute Maximum Ratings
Use of the IC in excess of absolute maximum ratings may result in damage to the IC. Assumptions should not be made
regarding the state of the IC (e.g., short mode or open mode) when such damage is suffered. If operational values are
expected to exceed the maximum ratings for the device, consider adding protective circuitry (such as fuses) to eliminate
the risk of damaging the IC.
(2) GND voltage
The potential of the GND, PGND pin must be the minimum potential in the system in all operating conditions.
(3) Thermal design
Use a thermal design that allows for a sufficient margin for power dissipation (Pd) under actual operating conditions
(4) Inter-pin Shorts and Mounting Errors
Use caution when orienting and positioning the IC for mounting on printed circuit boards. Improper mounting may result
in damage to the IC. Shorts between output pins or between output pins and the power supply and GND pins caused by
poor soldering or foreign objects may result in damage to the IC.
(5) Operation in Strong Electromagnetic Fields
Using this product in strong electromagnetic fields may cause IC malfunction. Caution should be exercised in
applications where strong electromagnetic fields may be present.
(6) ASO (Area of Safe Operation)
When using the IC, ensure that operating conditions do not exceed absolute maximum ratings or ASO of the output
transistors.
(7) Testing on application boards
When testing the IC on an application board, connecting a capacitor directly to a low-impedance pin may subject the IC
to stress. Always discharge capacitors completely after each process or step. The IC’s power supply should always be
turned off completely before connecting or removing it from a jig or fixture during the evaluation process. To prevent
damage from static discharge, ground the IC during assembly and use similar precautions during transport and storage.
(8) Electrical Characteristics
The electrical characteristics indicated in this datasheet may change upon the conditions of temperature, supply voltage,
and external components. Please validate/verify your design at the worst case conditions.
(9) Not of a radiation-resistant design.
(10) Back Electromotive Force
If a large inductive load is connected at the output pin that might cause introducing back electromotive force at the start
up and at the output disable, please insert protection diodes.
OUTPUT
PIN
Figure.29 Back Electromotive Force
(11) Regarding input pins of the IC
This monolithic IC contains P+ isolation and P substrate layers between adjacent elements in order to keep them isolated.
PN junctions are formed at the intersection of these P layers with the N layers of other elements, creating parasitic
diodes and/or transistors. For example (refer to the figure below):､
• When GND > Pin A and GND > Pin B, the PN junction operates as a parasitic diode
• When GND > Pin B, the PN junction operates as a parasitic transistor
Parasitic diodes occur inevitably in the structure of the IC, and the operation of these parasitic diodes can result in mutual
interference among circuits, operational faults, or physical damage. Accordingly, conditions that cause these diodes to
operate, such as applying a voltage lower than the GND voltage to an input pin (and thus to the P substrate) should be
avoided.
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TSZ02201-0F3F0AC00130-1-2
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BD95861MUV
Resistor
Transistor (NPN)
Pin B
Pin A
C
Pin B
B
E
Pin A
P
N
+
P
P+ N
N
N
Parasitic
element
P+
N
P substrate
Parasitic element
B
P
+
P
N
C
E
Parasitic
element
P substrate
GND
Parasitic element
GND
GND
Other adjacent
elements
GND
Figure.30 Example of IC structure
(12) Ground Wiring Pattern
When using both small-signal and large-current GND traces, the two ground traces should be routed separately but
connected to a single ground potential within the application in order to avoid variations in the small-signal ground
caused by large currents. Also ensure that the GND traces of external components do not cause variations on GND
voltage.
(13) Operating Condition
The electrical characteristics indicated in this datasheet are not guaranteed for the whole operational and temperature
ranges, however these characteristics do not significantly fluctuate within the operational and temperature ranges.
(14) Thermal shutdown (TSD) circuit
The IC incorporates a built-in thermal shutdown circuit, which is designed to turn the IC off completely in the event of
thermal overload. It is not designed to protect the IC from damage or guarantee its operation. ICs should not be used
after this function has activated, or in applications where the operation of this circuit is assumed. If the thermal
shutdown is activated while the load current exists, the output may possibly be latched off at the release of the thermal
shutdown.
TSD ON Temp.[℃]
175
(typ.)
Hysteresis Temp[℃]
25
(typ.)
(15) Heat Sink (FIN)
The heat sink (FIN) is connected to the substrate. Please connect it to GND.
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TSZ02201-0F3F0AC00130-1-2
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BD95861MUV
●Thermal Derating Curves
4
(1)3.55W
Power dissipation[W]
3.5
(1) 4 layer board
(All layers with 5505 mm2 copper heat dissipation pads)
θj-a=35.1℃/W
(2) 4 layer board
(6.28 mm2 copper heat dissipation pad on top and bottom layer,
5505 mm2 pad on 2nd and 3rd layer)
θj-a=56.8℃/W
(3) 1 layer board (6.28 mm2 copper heat dissipation pad)
θj-a=181.2℃/W
3
2.5
(2)2.20W
2
1.5
1
(3)0.70W
0.5
0
50
100
150
Ambient temperature[℃]
Figure.31 Thermal derating curve
(VQFN024V4040)
●Ordering Information
B
D
9
5
8
6
1
Part Number
M
U
V
Package
MUV: VQFN024V4040
-
E2
Packaging and forming specification
E2: Embossed tape and reel
●Physical Dimension Tape and Reel Information
VQFN024V4040
5
(Unit:mm)
●Marking Diagram
VQFN024V4040 (TOP VIEW)
Part Number Marking
9 5 8 6 1
LOT Number
1PIN MARK
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TSZ22111・15・001
22/23
TSZ02201-0F3F0AC00130-1-2
24.Mar.2022 Rev.006
BD95861MUV
●Revision History
Date
Revision
Changes
30.Aug.2012
001
New Release
18.Mar.2013
002
Revised the General Description
16.Apr.2014
003
Added the max on-duty graph of output voltage setting
18.Mar.2014
004
Revised the recommended BOM list
10.Aug.2017
005
Revised Tape and Reel Information, and Marking Diagram
24.Mar.2022
006
Revised formula number
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Notice
Precaution on using ROHM Products
1.
Our Products are designed and manufactured for application in ordinary electronic equipment (such as AV equipment,
OA equipment, telecommunication equipment, home electronic appliances, amusement equipment, etc.). If you
intend to use our Products in devices requiring extremely high reliability (such as medical equipment (Note 1), transport
equipment, traffic equipment, aircraft/spacecraft, nuclear power controllers, fuel controllers, car equipment including car
accessories, safety devices, etc.) and whose malfunction or failure may cause loss of human life, bodily injury or
serious damage to property (“Specific Applications”), please consult with the ROHM sales representative in advance.
Unless otherwise agreed in writing by ROHM in advance, ROHM shall not be in any way responsible or liable for any
damages, expenses or losses incurred by you or third parties arising from the use of any ROHM’s Products for Specific
Applications.
(Note1) Medical Equipment Classification of the Specific Applications
JAPAN
USA
EU
CHINA
CLASSⅢ
CLASSⅡb
CLASSⅢ
CLASSⅢ
CLASSⅣ
CLASSⅢ
2.
ROHM designs and manufactures its Products subject to strict quality control system. However, semiconductor
products can fail or malfunction at a certain rate. Please be sure to implement, at your own responsibilities, adequate
safety measures including but not limited to fail-safe design against the physical injury, damage to any property, which
a failure or malfunction of our Products may cause. The following are examples of safety measures:
[a] Installation of protection circuits or other protective devices to improve system safety
[b] Installation of redundant circuits to reduce the impact of single or multiple circuit failure
3.
Our Products are designed and manufactured for use under standard conditions and not under any special or
extraordinary environments or conditions, as exemplified below. Accordingly, ROHM shall not be in any way
responsible or liable for any damages, expenses or losses arising from the use of any ROHM’s Products under any
special or extraordinary environments or conditions. If you intend to use our Products under any special or
extraordinary environments or conditions (as exemplified below), your independent verification and confirmation of
product performance, reliability, etc, prior to use, must be necessary:
[a] Use of our Products in any types of liquid, including water, oils, chemicals, and organic solvents
[b] Use of our Products outdoors or in places where the Products are exposed to direct sunlight or dust
[c] Use of our Products in places where the Products are exposed to sea wind or corrosive gases, including Cl2,
H2S, NH3, SO2, and NO2
[d] Use of our Products in places where the Products are exposed to static electricity or electromagnetic waves
[e] Use of our Products in proximity to heat-producing components, plastic cords, or other flammable items
[f] Sealing or coating our Products with resin or other coating materials
[g] Use of our Products without cleaning residue of flux (Exclude cases where no-clean type fluxes is used.
However, recommend sufficiently about the residue.) ; or Washing our Products by using water or water-soluble
cleaning agents for cleaning residue after soldering
[h] Use of the Products in places subject to dew condensation
4.
The Products are not subject to radiation-proof design.
5.
Please verify and confirm characteristics of the final or mounted products in using the Products.
6.
In particular, if a transient load (a large amount of load applied in a short period of time, such as pulse, is applied,
confirmation of performance characteristics after on-board mounting is strongly recommended. Avoid applying power
exceeding normal rated power; exceeding the power rating under steady-state loading condition may negatively affect
product performance and reliability.
7.
De-rate Power Dissipation depending on ambient temperature. When used in sealed area, confirm that it is the use in
the range that does not exceed the maximum junction temperature.
8.
Confirm that operation temperature is within the specified range described in the product specification.
9.
ROHM shall not be in any way responsible or liable for failure induced under deviant condition from what is defined in
this document.
Precaution for Mounting / Circuit board design
1.
When a highly active halogenous (chlorine, bromine, etc.) flux is used, the residue of flux may negatively affect product
performance and reliability.
2.
In principle, the reflow soldering method must be used on a surface-mount products, the flow soldering method must
be used on a through hole mount products. If the flow soldering method is preferred on a surface-mount products,
please consult with the ROHM representative in advance.
For details, please refer to ROHM Mounting specification
Notice-PGA-E
© 2015 ROHM Co., Ltd. All rights reserved.
Rev.004
Precautions Regarding Application Examples and External Circuits
1.
If change is made to the constant of an external circuit, please allow a sufficient margin considering variations of the
characteristics of the Products and external components, including transient characteristics, as well as static
characteristics.
2.
You agree that application notes, reference designs, and associated data and information contained in this document
are presented only as guidance for Products use. Therefore, in case you use such information, you are solely
responsible for it and you must exercise your own independent verification and judgment in the use of such information
contained in this document. ROHM shall not be in any way responsible or liable for any damages, expenses or losses
incurred by you or third parties arising from the use of such information.
Precaution for Electrostatic
This Product is electrostatic sensitive product, which may be damaged due to electrostatic discharge. Please take proper
caution in your manufacturing process and storage so that voltage exceeding the Products maximum rating will not be
applied to Products. Please take special care under dry condition (e.g. Grounding of human body / equipment / solder iron,
isolation from charged objects, setting of Ionizer, friction prevention and temperature / humidity control).
Precaution for Storage / Transportation
1.
Product performance and soldered connections may deteriorate if the Products are stored in the places where:
[a] the Products are exposed to sea winds or corrosive gases, including Cl 2, H2S, NH3, SO2, and NO2
[b] the temperature or humidity exceeds those recommended by ROHM
[c] the Products are exposed to direct sunshine or condensation
[d] the Products are exposed to high Electrostatic
2.
Even under ROHM recommended storage condition, solderability of products out of recommended storage time period
may be degraded. It is strongly recommended to confirm solderability before using Products of which storage time is
exceeding the recommended storage time period.
3.
Store / transport cartons in the correct direction, which is indicated on a carton with a symbol. Otherwise bent leads
may occur due to excessive stress applied when dropping of a carton.
4.
Use Products within the specified time after opening a humidity barrier bag. Baking is required before using Products of
which storage time is exceeding the recommended storage time period.
Precaution for Product Label
A two-dimensional barcode printed on ROHM Products label is for ROHM’s internal use only.
Precaution for Disposition
When disposing Products please dispose them properly using an authorized industry waste company.
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Since concerned goods might be fallen under listed items of export control prescribed by Foreign exchange and Foreign
trade act, please consult with ROHM in case of export.
Precaution Regarding Intellectual Property Rights
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All information and data including but not limited to application example contained in this document is for reference
only. ROHM does not warrant that foregoing information or data will not infringe any intellectual property rights or any
other rights of any third party regarding such information or data.
2.
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Products with other articles such as components, circuits, systems or external equipment (including software).
3.
No license, expressly or implied, is granted hereby under any intellectual property rights or other rights of ROHM or any
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Other Precaution
1.
This document may not be reprinted or reproduced, in whole or in part, without prior written consent of ROHM.
2.
The Products may not be disassembled, converted, modified, reproduced or otherwise changed without prior written
consent of ROHM.
3.
In no event shall you use in any way whatsoever the Products and the related technical information contained in the
Products or this document for any military purposes, including but not limited to, the development of mass-destruction
weapons.
4.
The proper names of companies or products described in this document are trademarks or registered trademarks of
ROHM, its affiliated companies or third parties.
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Rev.004
Datasheet
General Precaution
1. Before you use our Products, you are requested to carefully read this document and fully understand its contents.
ROHM shall not be in any way responsible or liable for failure, malfunction or accident arising from the use of any
ROHM’s Products against warning, caution or note contained in this document.
2. All information contained in this document is current as of the issuing date and subject to change without any prior
notice. Before purchasing or using ROHM’s Products, please confirm the latest information with a ROHM sales
representative.
3.
The information contained in this document is provided on an “as is” basis and ROHM does not warrant that all
information contained in this document is accurate and/or error-free. ROHM shall not be in any way responsible or
liable for an y damages, expenses or losses incurred b y you or third parties resulting from inaccuracy or errors of or
concerning such information.
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