MP24830
4.5V – 90V, Programmable Frequency
White LED Driver
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MP24830 is a 90V white LED driver
suitable for either step-down or inverting
step-up/down applications. It supports a wide
input range with excellent load and line
regulation. Its programmable current limit
provides customized applications with a wide
power range. Current mode operation provides
a fast transient response and eases loop
stabilization. Fault condition protection includes
thermal shutdown, cycle-by-cycle peak-current
limiting, open-string protection, and output
short-circuit protection.
•
•
•
•
•
•
•
•
•
Programmable Maximum Output Current
Unique Step-Up/Down Operation (BuckBoost Mode)
Wide 4.5V-to-90V Operating Input Range
for Step-Down Applications (Buck Mode)
Adjustable Switching Frequency
Analog and PWM Dimming
0.2V Reference Voltage
10μA Shutdown Mode
No Minimum LED Quantity Required
Stable with Low ESR Output Ceramic
Capacitors
Cycle-by-Cycle Over-Current Protection
Thermal Shutdown Protection
Open-String Protection
Output Short-Circuit Protection
Available in 14-Pin SOIC and QFN
Packages
The MP24830 incorporates both DC and PWM
dimming onto a single control pin. The separate
input reference ground pin allows for direct
enable and/or dimming control for a positive-tonegative power conversion.
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•
•
•
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The MP24830 requires a minimal number of
readily-available external components. It is
available in 14-pin SOIC and QFN packages.
APPLICATIONS
•
•
•
General LED Illumination
Automotive LED Lighting
LCD Backlight
All MPS parts are lead-free, halogen free, and adhere to the RoHS directive. For
MPS green status, please visit MPS website under Quality Assurance.
“MPS” and “The Future of Analog IC Technology” are Registered Trademarks
of Monolithic Power Systems, Inc.
TYPICAL APPLICATION
VIN
DIM
EN
INGND
C1
C2
3 VDD
BST
Rcs
MP24830
CS
5 DIM
6 EN
U1
13
2
DR 1
14
SW
Q1
LED+
R9
499k
4 INGND
OVP 8
DIMO 11
12 VSS
FB 10
RSET COMP
9
7
C3
100pF
R6
100k
C4
4.3nF
R3
4.7k
C5
1nF
LEDQ2
Si4100DY
D2
D1
R10
C9
22pF
R7
MP24830 Rev. 1.02
www.MonolithicPower.com
4/29/2015
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
1
MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER
ORDERING INFORMATION
Part Number
Package
Top Marking
MP24830HS*
SOIC-14
MP24830
MP24830HL**
QFN-14
24830
* For Tape & Reel, add suffix –Z (e.g. MP24830HS–Z);
For RoHS Compliant Packaging, add suffix –LF (e.g. MP24830HS–LF–Z)
** For Tape & Reel, add suffix –Z (e.g. MP24830HL–Z);
For RoHS Compliant Packaging, add suffix –LF (e.g. MP24830HL–LF–Z)
PACKAGE REFERENCE
TOP VIEW
TOP VIEW
DR
1
14
SW
CS
2
13
BST
VDD
3
12
VSS
INGND
4
11
DIMO
DIM
5
10
FB
EN
6
9
COMP
RSET
7
8
OVP
DR
1
14
SW
CS
2
13
BST
VDD 3
12
VSS
INGND 4
11
DIMO
DIM 5
10
FB
EN
6
9
COMP
RSET 7
8
OVP
EXPOSED PAD
ON BACKSIDE
SOIC14
QFN14
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance
Supply Voltage VDD – VSS, VCS – VSS ............90V
VSW – VSS .............................. -0.3V to VIN + 0.3V
VBST, VDR ..............................................VSW + 6V
VEN – VINGND, VDim – VINGND ............. -0.3V to +6V
VINGND – VSS ................................... -0.3V to 90V
Other pins – VSS ............................. -0.3V to +6V
(2)
Continuous Power Dissipation (TA = +25°C)
SOIC-14 ....................................................1.4W
QFN-14 ......................................................2.6W
Junction Temperature .............................. 150°C
Lead Temperature ................................... 260°C
Storage Temperature ............... -65°C to +150°C
SOIC-14 ................................. 86 ...... 38 ... °C/W
QFN-14................................... 49 ...... 10 ... °C/W
Recommended Operating Conditions
(3)
(4)
θJA
θJC
Notes:
1) Exceeding these ratings may damage the device.
2) The maximum allowable power dissipation is a function of the
maximum junction temperature TJ (MAX), the junction-toambient thermal resistance θJA, and the ambient temperature
TA. The maximum allowable continuous power dissipation at
any ambient temperature is calculated by PD (MAX) = (TJ
(MAX)-TA)/θJA. Exceeding the maximum allowable power
dissipation will cause excessive die temperature, and the
regulator will go into thermal shutdown. Internal thermal
shutdown circuitry protects the device from permanent
damage.
3) The device function is not guaranteed outside of the
recommended operating conditions.
4) Measured on JESD51-7, 4-layer PCB.
Supply Voltage VDD – VSS ................ 4.5V to 85V
Operating Junction Temp. (TJ) -40°C to +125°C
MP24830 Rev. 1.02
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4/29/2015
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2
MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER
ELECTRICAL CHARACTERISTICES
VIN = 12V, TJ = +25°C, all voltages with respect to VSS, unless otherwise noted.
Parameters
Symbol
Feedback Voltage
Feedback Current
Under Voltage Lockout Threshold Rising
Under Voltage Lockout Threshold Hysteresis
Operation Current (Quiescent)
Supply Current (Quiescent) at EN Off
Gate Driver Pull-Up Impedance
Gate Driver Pull-Down Impedance
Gate Driver Output-High to SW
Gate Driver Output-Low to SW
DIMO Source Current
DIMO Sink Current
DIMO Output High
DIMO Output Low
Oscillator Frequency
VFB
IFB
VUVLOTH
VUVLOHY
IQ
IOFF
RPULL UP
RPULL Down
VOH-SW
VOL-SW
IDIMOSC
IDIMOSK
VDIMOH
VDIMOL
fSW
Min. Oscillator Frequency
fSWMIN
Max. Oscillator Frequency
fSWMAX
Foldback Frequency
fSWFB
GM of Error Amplifier
Condition
4.5V ≤ VIN ≤ 90V
VFB = 0.22V
Min
0.192
-50
3.7
VEN = 2V, VFB = 0.25V
VEN=0V
IDR=10mA
IDR=10mA
5.6
IDR=10mA
IDR=10mA
VFB = 0.15V,
RSET=100kΩ
VFB = 0.15V,
RSET=380kΩ
VFB = 0.15V, RSET open
4.6
Typ
0.2
4.1
160
0.8
10
25
7
5.8
0.1
0.05
0.05
5
0.4
Max
0.208
50
4.4
Units
0.5
V
nA
V
mV
mA
μA
Ω
Ω
V
V
A
A
V
V
1.1
23
0.3
145
215
265
kHz
30
50
75
kHz
245
365
465
kHz
VFB = 0V, VOVP=0V,
RSET=100kΩ
30
kHz
GM
80
μs
Error Amplifier Output Current
IOamp
40
μA
Current Sensing Gain
GCS
20
High-Side Current Limit Threshold
VCLTH
45
mV
Min. Off-Time
tOFFMIN
280
ns
100
3.7
ns
μA
V
V
V
V
(5)
Min. On-Time
EN Input Current
EN OFF Threshold (w/Respect to INGND)
EN ON Threshold (w/Respect to INGND)
Min. DIM Threshold
Max. DIM Threshold
LED-Short Threshold for Immediate LatchOff
LED Short Delay for Latch-Off
LED Short Threshold
(5)
Thermal Shutdown
Open LED OV Threshold
Open LED OV Hysteresis
tON
IENIN
VENOFFTH
VENONTH
VDIMTHL
VDIMTHH
TTSHD
VOVPTH
VOVPHY
VFB = 0.19V,
RSET=100kΩ
VEN = 3.3V
VEN Falling
VEN Rising
VFB = 0.2V
VFB = 0.2V
0.4
0.6
1.55
1.1
0.7
1.75
1.4
0.8
1.95
600
mV
450
300
160
1.2
50
μs
mV
°C
V
mV
1.3
Notes:
5) Guaranteed by design.
MP24830 Rev. 1.02
www.MonolithicPower.com
4/29/2015
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© 2015 MPS. All Rights Reserved.
3
MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER
PIN FUNCTIONS
SOIC14
Name Description
1
DR
2
CS
3
4
5
6
7
8
9
10
Driver Output. Connect it to the high-side MOSFET gate.
High-Side Current Sense. For over-current protection and current-mode control.
Supply Voltage. Operates from a 4.5V-to-85V unregulated input (with respect to VSS). Needs
VDD
C1 to prevent large input voltage spikes.
INGND Input Ground Reference. Reference for the EN/DIM signal.
Dimming Command Input. Selects for DC or PWM dimming. When the DIM pin voltage (with
respect to INGND) rises from 0.6V to 1.95V, the LED current changes from 0% to 100% of the
DIM maximum LED current. For PWM dimming, apply a 100Hz-to-2kHz square wave with an
amplitude greater than 2V. For combined analog and PWM dimming, apply a 100Hz-to-2kHz
square wave signal with amplitude from 0.6V to 1.95V.
EN
Enable.
Frequency Set. Connect a resistor to VSS to set the switching frequency, and a 1nF capacitor
RSET
to VSS to bypass the noise. Leaving this pin open for the 350kHz default operating frequency.
Over-Voltage Protection. Use a voltage divider to program OVP threshold. When the OVP pin
voltage reaches the 1.2V shutdown threshold, the switch turns off and recovers when the OVP
voltage decreases sufficiently. When the OVP pin voltage (with respect to VSS) falls below
OVP
0.4V and the FB pin voltage falls below 0.1V, the chip interprets this as a short circuit and the
operating frequency will fold back. Program the OVP pin voltage from 0.4V to 1.2V for normal
operation.
Error Amplifier Output. Connect a 1nF or larger capacitor on COMP and an RC network from
COMP
FB to COMP to improve the stability and to provide soft-start and PWM dimming.
LED Current Feedback Input. A current-sensing resistor between FB and VSS provides circuit
FB
feedback. The regulation voltage is 0.2V. Short-circuit protection triggers If the FB voltage
exceeds 300mV for 450µs or the FB voltage exceeds 600mV.
11
DIMO
12
VSS
13
BST
14
SW
DIM Output. Provides for accurate PWM diming control following DIM logic. Connect to the
gate of the external dimming MOSFET. Leave floating if dimming accuracy is not a concern.
Power Return. Connect to the circuit’s point of lowest potential, which is typically the anode of
the Schottky rectifier. Acts as the voltage reference for the regulated output voltage, and layout
requires extra consideration. Place this node outside of the D1-to-C1 ground path to prevent
switching current spikes from inducing voltage noise. Connect the exposed pad to this pin.
Bootstrap. Connect a capacitor between the SW and BST pins to form a floating supply across
the power switch driver. Use a 100nF or larger ceramic capacitor to provide sufficient energy
to drive the power switch’s gate above the supply voltage.
Switch. Connect to the source of the external MOSFET
MP24830 Rev. 1.02
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4/29/2015
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© 2015 MPS. All Rights Reserved.
4
MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER
TYPICAL PERFORMANCE CHARACTERISTICS
VEN=5V, VIN=5V to 85V, IOUT=0.5A, L=47μH, TA=25°C, unless otherwise noted.
Efficiency vs.
Input Voltage
Efficiency vs.
String Voltage
100
90
8LED
85
3LED
80
75
0
20
40
60
0.4
96
6LED
80
VIN=40V
92
VIN=20V
88
84
80
10
100
VIN VOLTAGE (V)
100
4LED
2LED
0
20
40
60
80
80
500
5
12
19
26
33
200
100
40
60
DIMMING (%)
80
100
50
60
70
2LED, ILED=1A
0.2
0.0
-0.2
-0.4
Buck-Boost ILED vs.
Analog Dimming
VIN=25V, 3LED, FDIM=0.2kHz
1000
VIN=20V, 3LED, FDIM=0.2kHz
800
300
200
100
0
40
INPUT VOLTAGE (V)
IOUT CURRENT (A)
300
30
-0.6
20 30 40 50 60 70 80 90 100
40
400
400
20
0.4
Buck ILED vs.
PWM Dimming
IOUT CURRENT (A)
IOUT CURRENT (mA)
0.6
LED STRING VOLTAGE (V)
VIN=25V, 3LED, FDIM=0.2kHz
20
-0.4
Buck ILED Line
Regulation vs. VIN
85
70
100
6LED
10LED
INPUT VOLTAGE (V)
90
Buck-Boost ILED vs.
PWM Dimming
0
0
8LED
-0.2
-0.6
10
40
VIN=50V, ILED=1A
VIN VOLTAGE (V)
500
35
75
75
70
30
ILED REGULATION (%)
EFFICIENCY (%)
EFFICIENCY (%)
90
80
25
95
6LED
85
20
3LED
0.0
Buck Efficiency vs.
String Voltage
ILED=1A
95
15
0.2
LED STRING VOLTAGE (V)
Buck Efficiency vs.
Input Voltage
100
ILED REGULATION (%)
10LED
EFFICIENCY (%)
EFFICIENCY (%)
0.6
100
95
70
ILED Line Regulation vs.
VIN
0
20
40
60
DIMMING (%)
80
100
600
400
200
0
0.7
0.9
1.1
1.3
1.5
1.7
1.9
ANALOG DIMMING VOLTAGE (V)
MP24830 Rev. 1.02
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5
MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VEN=5V, VIN=5V to 85V, IOUT=0.5A, L=47μH, TA=25°C, unless otherwise noted.
FSW vs. Temperature
500
230
60
400
220
50
40
30
20
-50
-10
30
70
110
200
200
190
100
180
0
-50
150
-10
30
70
110
170
-50
150
7.0
1000
140
6.5
900
120
6.0
800
5.5
700
5.0
600
4.5
-50
-10
30
70
110
500
-50
150
Buck ILED vs.
Analog Dimming
1000
30
70
110
150
-10
30
70
110
150
-10
30
70
110
150
100
80
60
40
-50
Buck-Boost Steady State
Buck Steady State
VIN = 8V, 3LED, IOUT = 1A
VIN = 14V, 1LED, IOUT = 1A
VIN=20V, 3LED, IOUT=1A, FDIM=0.2kHz
800
VIN
20V/div.
600
VSW
20V/div.
400
VOUT
10V/div.
IL
1A/div.
200
0
-10
IQ Current vs. Temperature
INPUT VOLTAGE (V)
VBST VOLTAGE (V)
210
300
VBST vs. Temperature
IOUT CURRENT (A)
VFB vs. Temperature
70
DEFAULT FSW (kHz)
VCS VOLTAGE (V)
VCS vs. Temperature
0.7
0.9
1.1
1.3
1.5
1.7
VIN
50V/div.
VSW
20V/div.
VOUT
5V/div.
IL
1A/div.
1.9
ANALOG DIMMING VOLTAGE (V)
MP24830 Rev. 1.02
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6
MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VEN=5V, VIN=5V to 85V, IOUT=0.5A, L=47μH, TA=25°C, unless otherwise noted.
Buck-Boost
Buck-Boost
Buck PWM Dimming
VIN = 25V, 3LED, FDIM = 200Hz/50%
PWM Dimming
Analog Dimming
VIN = 25V, 3LED, FDIM = 200Hz/50%
VIN = 25V, 3LED, VDIM = 0.9A
VIN
20V/div.
VSW
50V/div.
VIN
50V/div.
VSW
50V/div.
VIN
20V/div.
VSW
20V/div.
VDIM
5V/div.
VDIM
2V/div.
VDIM
5V/div.
IL
1A/div.
IL
1A/div.
IL
1A/div.
Buck-Boost
Power Ramp Up
Buck-Boost
Enable Power Up
Buck-Boost
Enable Power Down
VIN = 8V, 3LED
VIN =40V, 3LED
VIN = 40V, 3LED
VIN
5V/div.
VSW
10V/div.
VOUT
10V/div.
IL
0.5A/div.
VIN
20V/div.
VSW
20V/div.
VOVP
1V/div.
IL
1A/div.
VIN
50V/div.
VSW
50V/div.
VIN
50V/div.
VSW
50V/div.
VEN
5V/div.
VEN
5V/div.
IL
1A/div.
IL
1A/div.
Buck-Boost
Open LED Protection
Buck-Boost
Short LED Protection
Buck-Boost
Short LED to VSS
VIN = 25V, 3LED, ILED = 1A
VIN = 16V, 3LED
VIN = 25V, 3LED
VIN
10V/div.
VSW
20V/div.
VIN
20V/div.
VSW
50V/div.
VOUT
10V/div.
VOUT
10V/div.
IL
1A/div.
IL
1A/div.
MP24830 Rev. 1.02
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4/29/2015
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© 2015 MPS. All Rights Reserved.
7
MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER
FUNCTIONAL BLOCK DIAGRAM
CS
DR
DIM
DIMO
COMP
Figure 1: Functional Block Diagram
MP24830 Rev. 1.02
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4/29/2015
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8
MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER
OPERATION
The MP24830 is a current-mode regulator. The
error amplifier (EA) output voltage is
proportional to the peak inductor current.
At the beginning of a cycle, M1 is off. The EA
output voltage exceeds the current sense
amplifier output, and the current comparator’s
output is low. The rising edge of the CLK signal
(its frequency equals the switching frequency)
triggers the RS flip-flop. The driver turns on the
external MOSFET, thus connecting the SW pin
and inductor to the input supply.
The current-sense amplifier (CSA) senses the
increasing inductor current. The PWM
comparator compares the sum of the ramp
generator and the CSA output against the
output of the error amplifier. When the sum of
the CSA output and the ramp generator signal
exceeds the EA output voltage, the RS flip-flop
resets and driver turns off the external
MOSFET. The external Schottky rectifier diode
(D1) conducts the inductor current.
If the sum of the CSA output and the ramp
compensation signal does not exceed the EA
output for a whole cycle, then the falling edge of
the CLK resets the flip-flop.
The output of the EA integrates the voltage
difference between the feedback and the 0.2V
reference: A value of 0.2V-VFB increases the EA
output voltage. Since the EA output voltage is
proportional to the peak inductor current,
increasing its voltage also increases the current
delivered to the output.
LED Open Protection
If the LED is open, there is no voltage on the
FB pin. The duty cycle increases until OVPVSS reaches the shutdown threshold set by the
external resistor divider. The top switch remains
off until the voltage OVP-VSS drops below 1.2V.
LED Short Protection
If the FB voltage exceeds 600mV, the latches
off immediately and DIMO goes low. If the FB
voltage exceeds 300mV for 450µs, the IC
latches off and DIMO is pulled low. The EN
needs to reset to restart the IC.
Dimming Control
The MP24830 allows both DC and PWM
dimming on the DIM pin. For analog dimming, a
voltage range from 0.6V to 1.95V linearly sets
the LED current from 0% to 100% of the
maximum LED current. DIM voltages exceeding
2V results in the maximum LED current. For
PWM dimming, use a square signal with an
amplitude (VDIM – VINGND) that exceeds 1.95V.
For good dimming linearity, select a PWM
frequency in range of 100Hz to 2kHz. For a
higher dimming frequency or dimming ratio, use
the DIMO pin to control an external dimming
MOSFET. For combined analog and PWM
dimming, apply a PWM signal with amplitude of
0.6V to 1.95V on the DIM pin.
Output Short-Circuit Protection
The MP24830 integrates output short-circuit
protection (SCP) to foldback the operating
frequency and decrease power consumption
when the output is shorted to VSS. Such shorts
cause the voltage on the OVP pin to drop below
0.4V, and the FB pin senses no voltage (>Cp):
(1)Compensation network for Buck-boost
application
The DC modulator gain of the buck-boost
power stage (from the output current to the
control voltage on COMP pin) is:
VOUT × VIN
VOUT + VIN
DCGain _ PS =
VOUT
I
* VOUT
20 × RCS × (
+ OUT
) × (RFB + RLED )
RFB + RLED VOUT + VIN
Where RCS is the switch current sensing resistor
on CS pin, RLED is the equivalent dynamic
resistance of the LED load, as shown in Figure
5.
VIN2
2π × L × IOUT × (VOUT + VIN )
RCOMP =
fc
gm × RFB × DCGain _ PS * fP _ PS
That is:
RCOMP =
2πfc × COUT × 20 × RCS × (RFB + RLED )(VOUT + VIN )
gm × RFB × VIN
Use the maximum input voltage and minimum
output voltage to calculate RCOMP.
Step 2: Select CZ
Set the zero of the compensation network to
cancel the minimum pole of the power stage to
get:
Cz =
1
2π × fP _ PS × RCOMP
Choose CZ with the maximum input voltage and
maximum output voltage.
Step 3: Select CP
ΔILED
RLED =
ΔVLED
ΔI LED
ΔVLED
Set the pole of the compensation network to
cancel the minimum RHP zero to get:
Cp ≈
1
2π × fz _ RHP × RCOMP
Choose CP with the minimum input voltage and
maximum output voltage.
Figure 5: LED Dynamic Resistance Equivalent
The dominant low-frequency pole of the buckboost power stage is:
MP24830 Rev. 1.02
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© 2015 MPS. All Rights Reserved.
11
MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER
(2)Compensation network for Buck
application
The DC modulator gain of the buck power stage
(from the output current to the control voltage)
is:
DCGain _ Buck =
1
20 × RCS
The dominant, low frequency pole of the buck
power stage is:
fP _ Buck =
1
2 π × (RFB + RLED + RESR ) × COUT
The zero produced by the ESR of the output
capacitor is:
fZ _ ESR =
1
2π × COUT * RESR
Where RESR is the ESR of the output capacitor.
Step 1: Select RCOMP
Choose a crossing frequency, fC, below 1/5×fC
to derive the compensation network as follows
(assume CZ>>CP):
RCOMP _ Buck =
fc
gm × RFB × DCGain _ Buck * fp _ Buck
That is:
RCOMP _ Buck =
2πfc × COUT × 20 × RCS × (RFB + RLED + RESR )
gm × RFB
Step 2: Select CZ
Set the zero of the compensation network to
cancel the minimum pole of the Buck power
stage to get:
Cz _ Buck
1
=
2π × fP _ Buck × RCOMP _ Buck
Step 3: Select CP
Set the pole of the compensation network to
cancel the ESR zero. If the ESR zero is too
high, set this pole at around 3 to 5 times fC:
Cp ≈ max(
1
1
,
)
2π × fz _ ESR × RCOMP _ Buck 2π × 5fc × RCOMP _ Buck
Selecting the Inductor
Select the inductor based on the input voltage,
the output voltage, and the LED current. Select
the inductor to make the circuit operate in
continuous current mode (CCM). Select the
inductor current rating to ensure that the
inductor does not saturate and with
consideration to power consumption based on
the DC resistance.
(1) Selecting the Inductor for Buck-Boost
Applications
For buck-boost applications, select the inductor
based on the following equation:
L=
fSW
VIN × VOUT
× (VIN + VOUT ) × ΔIL
Where ΔIL is the peak-to-peak inductor current
ripple. Design ΔIL to be between 30% and 60%
of the average current of the inductor, which is:
IL _ AVG = ILED * (1 +
VOUT
)
VIN
Select the inductor with a DC current rating that
ensurew that the inductor does not saturated at
the peak current of:
IL _PK = IL _ AVG + 0.5ΔIL
(2) Selecting the Inductor for Buck Applications
For buck applications, derive the inductance
value from the following equation.
L=
VOUT × ( VIN − VOUT )
VIN × ΔIL × f SW
Where ΔIL is the peak-to-peak inductor ripple
current.
Choose the inductor ripple current to around
30% to 60% of the maximum load current. The
maximum inductor peak current is calculated as:
IL(MAX ) = ILOAD +
ΔIL
2
Selecting the Input Capacitor
The input capacitor reduces the surge current
drawn from the input supply and the switching
noise from the device. For best results, use
MP24830 Rev. 1.02
www.MonolithicPower.com
4/29/2015
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
12
MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER
ceramic capacitors with X7R dielectrics with low
ESR and small temperature coefficients.
Select a large-enough capacitor to limit input
the voltage ripple, ΔVIN, to less than 5% to 10%
of the DC value.
CIN >
IL _ AVG × VOUT
fSW × ΔVIN × (VIN + VOUT )
Selecting the Output Capacitor
The output capacitor limits the output voltage
ripple, ΔVOUT (normally less than 1% to 5% of
the DC value), and ensures feedback loop
stability. Use an output capacitor with
impedance at the switching frequency. Use
ceramic capacitors with low ESR characteristics.
COUT >
fSW
ILED × VOUT
× ΔVOUT × (VIN + VOUT )
PC Board Layout
Place the high-current paths (VSS, VDD and
SW) very close to the device with short, direct,
and wide traces. Place the input capacitor as
close as possible to the VDD and VSS pins.
Place the external feedback resistors next to
the FB pin. Keep the switch node traces short
and away from the feedback network.
Pay special attention is required to the
switching frequency loop layout, which should
be as small as possible.
For buck applications, the switching frequency
loop is composed of the input capacitor, the
power MOSFET and the Schottky diode. Place
the Schottky diode close to the power MOSFET
and the input capacitor.
For buck-boost or boost applications, the
switching frequency loop is composed of the
input capacitor, the power MOSFET, the
Schottky diode and the output capacitor. Make
this component loop as small as possible. For
most applications, place the output capacitor
close to the input capacitor and the power
MOSFET.
MP24830 Rev. 1.02
www.MonolithicPower.com
4/29/2015
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
13
MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER
TYPICAL APPLICATION CIRCUIT
Figure 6: Step-up/down White LED Driver Application
Figure 7: Step-down Constant Voltage Converter Application
MP24830 Rev. 1.02
www.MonolithicPower.com
4/29/2015
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
14
MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER
PACKAGE INFORMATION
SOIC-14
0.338(8.55)
0.344(8.75)
0.024(0.61)
8
14
0.063
(1.60)
0.150
(3.80)
0.157
(4.00)
PIN 1 ID
0.050(1.27)
0.228
(5.80)
0.244
(6.20)
0.213
(5.40)
7
1
TOP VIEW
RECOMMENDED LAND PATTERN
0.053(1.35)
0.069(1.75)
SEATING PLANE
0.050(1.27)
BSC
0.013(0.33)
0.020(0.51)
0.004(0.10)
0.010(0.25)
SEE DETAIL "A"
SIDE VIEW
FRONT VIEW
0.010(0.25)
x 45o
0.020(0.50)
GAUGE PLANE
0.010(0.25) BSC
0o-8o
0.016(0.41)
0.050(1.27)
0.0075(0.19)
0.0098(0.25)
NOTE:
1) CONTROL DIMENSION IS IN INCHES. DIMENSION IN
BRACKET IS IN MILLIMETERS.
2) PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH,
PROTRUSIONS OR GATE BURRS.
3) PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH
OR PROTRUSIONS.
4) LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING)
SHALL BE 0.004" INCHES MAX.
5) DRAWING CONFORMS TO JEDEC MS-012, VARIATION AB.
6) DRAWING IS NOT TO SCALE.
DETAIL "A"
MP24830 Rev. 1.02
www.MonolithicPower.com
4/29/2015
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
15
MP24830 — 4.5V–90V, PROGRAMABLE FREQUENCY WHITE LED DRIVER
QFN-14
2.90
3.10
1.60
1.80
0.30
0.50
PIN 1 ID
SEE DETAIL A
PIN 1 ID
MARKING
1
14
0.18
0.30
3.20
3.40
3.90
4.10
PIN 1 ID
INDEX AREA
0.50
BSC
7
8
TOP VIEW
BOTTOM VIEW
0.80
1.00
0.20 REF
PIN 1 ID OPTION A
0.30x45” TYP.
PIN 1 ID OPTION B
R0.20 TYP.
0.00
0.05
SIDE VIEW
DETAIL A
2.90
0.70
NOTE:
1.70
1) ALL DIMENSIONS ARE IN MILLIMETERS.
2) EXPOSED PADDLE SIZE DOES NOT INCLUDE MOLD FLASH.
3) LEAD COPLANARITY SHALL BE 0.10 MILLIMETER MAX.
4) JEDEC REFERENCE IS MO-229, VARIATION VGED-4.
5) DRAWING IS NOT TO SCALE.
0.25
3.30
0.50
RECOMMENDED LAND PATTERN
NOTICE: The information in this document is subject to change without notice. Users should warrant and guarantee that third
party Intellectual Property rights are not infringed upon when integrating MPS products into any application. MPS will not
assume any legal responsibility for any said applications.
MP24830 Rev. 1.02
www.MonolithicPower.com
4/29/2015
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
16
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