MP24833-A
55V, 3A,
White LED Driver
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MP24833-A is a 55V, 3A, white LED driver
suitable for step-down, inverting step-up/stepdown, and step-up applications. The MP24833A achieves 3A of output current with excellent
load and line regulation over a wide input
supply range.
Current mode operation provides a fast
transient response and eases loop stabilization.
Full protection features include thermal shutdown,
cycle-by-cycle peak current limiting, open-string
protection, and output short-circuit protection
(SCP).
The MP24833-A incorporates both DC and
PWM dimming into a single control pin. The
separate input reference ground pin allows for
direct enable and/or dimming control for a
positive-to-negative power conversion.
The MP24833-A requires a minimal number of
readily
available,
standard,
external
components and is available in a SOIC-8 EP
package.
3A Maximum Output Current
Unique
Step-Up/Step-Down
Operation
(Buck-Boost Mode)
Wide 4.5V-to-55V Operating Input Range
for Step-Down Applications (Buck Mode)
0.15Ω Internal Power MOSFET Switch
Fixed 210kHz Switching Frequency
Analog and PWM Dimming
0.2V Reference Voltage
6μA Shutdown Mode
No Minimum Number of LEDs Required
Stable with Low ESR Output Ceramic
Capacitors
Cycle-by-Cycle Over-Current Protection
(OCP)
Thermal Shutdown Protection
Open-String Protection
Output Short-Circuit Protection (SCP)
Available in a SOIC-8 EP Package
APPLICATIONS
General LED Illumination
LCD Backlight Panels
Notebook Computers
Automotive Internal Lighting
Portable Multimedia Players
Portable GPS Devices
All MPS parts are lead-free, halogen-free, and adhere to the RoHS
directive. For MPS green status, please visit the MPS website under
Quality Assurance. “MPS” and “The Future of Analog IC Technology” are
registered trademarks of Monolithic Power Systems, Inc.
TYPICAL APPLICATION
3
CIN
EN/DIM
5
ON
SW
7
CBST
8
L
EN/DIM
D
OFF
DC or PWM Input
6
INGND
FB
VSS
Co
LEDs
BST
ROVP1
VDD
ROVP2
1
VIN
OVP
4
R FB
2
MP24833-A Rev. 1.02
www.MonolithicPower.com
3/29/2019
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2019 MPS. All Rights Reserved.
1
MP24833-A – 55V, 3A, WHITE LED DRIVER
ORDERING INFORMATION
Part Number*
Package
Top Marking
MP24833-AGN
SOIC-8 EP
See Below
* For Tape & Reel, add suffix –Z (e.g. MP24833-AGN–Z)
TOP MARKING
M24833-A: Part number
LLLLLLLL: Lot number
MPS: MPS prefix
Y: Year code
WW: Week code
PACKAGE REFERENCE
SOIC-8 EP
MP24833-A Rev. 1.02
www.MonolithicPower.com
3/29/2019
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2019 MPS. All Rights Reserved.
2
MP24833-A – 55V, 3A, WHITE LED DRIVER
ABSOLUTE MAXIMUM RATINGS (1)
Thermal Resistance (4)
Supply voltage (VDD - VSS) ............................ 57V
VSW - VSS ............................... -0.3V to VIN + 0.3V
VBST........................................................ VSW + 6V
VEN/DIM - VINGND ................................. -0.3V to +6V
VINGND - VSS ...................................... -0.3V to 57V
Other pins - VSS ............................... -0.3V to +6V
Continuous power dissipation (TA = +25°C) (2)
SOIC-8 EP .................................................. 2.5W
Junction temperature ................................ 150°C
Lead temperature...................................... 260°C
Storage temperature .................-65°C to +150°C
SOIC-8 EP ............................... 50 ...... 10... °C/W
Recommended Operating Conditions (3)
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 produces an excessive die temperature, causing
the regulator to 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 55V
Maximum junction temp. (TJ).. ............... .+125°C
MP24833-A Rev. 1.02
www.MonolithicPower.com
3/29/2019
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2019 MPS. All Rights Reserved.
3
MP24833-A – 55V, 3A, WHITE LED DRIVER
ELECTRICAL CHARACTERISTICS
VIN = 12V, TJ = -40°C~125°C, all voltages with respect to VSS, unless otherwise noted.
Parameters
Feedback voltage
Feedback current
Switch on resistance
Switch leakage
Current limit
Oscillator frequency
Foldback frequency
Maximum duty cycle
Minimum on time (5)
Under-voltage lockout threshold rising
Under voltage lockout threshold hysteresis
EN input current
EN off threshold (with respect to INGND)
EN on threshold (with respect to INGND)
Minimum EN dimming threshold
Maximum EN dimming threshold
Supply current (quiescent)
Supply current (quiescent) at EN off
Thermal shutdown (6)
Thermal shutdown recovery hysteresis
Open LED OV threshold
Open LED OV hysteresis
Symbol Condition
VFB
4.5V VIN 55V
IFB
VFB = 0.22V
RDS(ON)
VEN = 0V, VSW = 0V
Min
0.19
-100
150
3
145
fSW
VFB = 0V, VOVP = 0V
85
tON
3
IQ
Ioff
VOVP_th
VOVP_hys
VEN = 2V
VEN falling
VEN rising
VFB = 0V
VFB = 0.2V
VEN = 2V, VFB = 1V
VEN = 0V
Typ
0.2
4.8
210
37
91
100
3.3
200
Max
0.21
100
280
1
275
97
3.6
2.1
0.4
0.57
1.23
2.3
0.67
1.35
0.6
6
150
15
2.43
80
0.6
0.77
1.47
0.8
12
2.6
Units
V
nA
mΩ
μA
A
kHz
kHz
%
ns
V
mV
μA
V
V
V
V
mA
μA
°C
°C
V
mV
NOTES:
5) Guaranteed by design.
6) Guaranteed by characterization.
MP24833-A Rev. 1.02
www.MonolithicPower.com
3/29/2019
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2019 MPS. All Rights Reserved.
4
MP24833-A – 55V, 3A, WHITE LED DRIVER
TYPICAL PERFORMANCE CHARACTERISTICS
MP24833-A Rev. 1.02
www.MonolithicPower.com
3/29/2019
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2019 MPS. All Rights Reserved.
5
MP24833-A – 55V, 3A, WHITE LED DRIVER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
Performance waveforms are tested on the evaluation board in the Design Example section.
VIN = 20V, ILED = 1A, 7WLEDs in series, L = 68µH, TA = 25°C, buck-boost application, unless
otherwise noted.
89.5
1000
1000
800
800
88
600
600
87.5
400
400
200
200
89
88.5
87
86.5
86
12
SW-VSS
20V/div.
VOUT
20V/div.
14
16
18
20
22
0
0.5
24
VSW
20V/div.
0.9
1.1
1.3
0
0
1.5
VSW
20V/div.
VSW
20V/div.
VOUT
1V/div.
VOUT
1V/div.
IL
1A/div.
IOUT
500mA/div.
IL
1A/div.
IOUT
500mA/div.
VSW
20V/div.
VOUT
20V/div.
VSW
20V/div.
VOUT
20V/div.
IL
1A/div.
IL
1A/div.
IOUT
500mA/div.
ISHORT
500mA/div.
IL
1A/div.
IOUT
500mA/div.
0.7
0.2
0.4
0.6
0.8
1
VPWM
2V/div.
IL
1A/div.
IOUT
500mA/div.
MP24833-A Rev. 1.02
www.MonolithicPower.com
3/29/2019
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2019 MPS. All Rights Reserved.
6
MP24833-A – 55V, 3A, WHITE LED DRIVER
PIN FUNCTIONS
Pin #
1
2
3
4
5
6
7
8
Name
Description
Supply voltage. The MP24833-A operates from a 4.5V-to-55V unregulated input (with
respect to VSS). An input capacitor is needed to prevent large voltage spikes from appearing
at input.
VSS, Power return. VSS is the voltage reference for the regulated output voltage, and requires
Exposed extra care during layout. Connect VSS to the lowest potential in the circuit, which is the anode
Pad
of the Schottky rectifier, typically. The exposed pad is also connected to VSS.
Over-voltage protection. Use a voltage divider to program the OVP threshold. When the
OVP voltage reaches the shutdown threshold (2.43V), the switch turns off and recovers when
the OVP voltage drops to its normal operating range. When the voltage (with respect to VSS)
OVP
drops below 0.2V, and the FB voltage is below 0.1V, the chip treats this as a short circuit and
the operating frequency folds back. Program the OVP voltage from 0.2V to 2.43V for normal
operation.
LED current feedback input. FB senses the current across the sensing resistor between FB
FB
and VSS. Connect the current sensing resistor from the bottom of the LED strings to VSS. FB
is connected to the bottom of the LED strings. The regulation voltage is 0.2V.
On/off control input and dimming command input. A voltage greater than 0.67V turns on
the chip. EN/DIM implements both DC and PWM dimming. When the EN/DIM voltage (with
respect to INGND) rises from 0.67V to 1.35V, the LED current changes from 0% to 100% of
EN/DIM
the maximum LED current. To use PWM dimming, apply a 100Hz-to-2kHz square wave
signal with an amplitude greater than 1.5V to EN/DIM. For combined analog and PWM
dimming, apply a 100Hz-to-2kHz square wave signal with an amplitude from 0.67V to 1.35V.
INGND Input ground reference. INGND is the reference for the EN/DIM signal.
Bootstrap. Connect a capacitor between SW and BST to form a floating supply for the power
BST
switch driver. Use a ceramic capacitor 100nF or larger to provide sufficient energy to drive the
power switch with this supply voltage.
Switch output. SW is the source of the internal MOSFET. Connect SW to the power inductor
SW
and the cathode of the rectifier diode.
VDD
MP24833-A Rev. 1.02
www.MonolithicPower.com
3/29/2019
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2019 MPS. All Rights Reserved.
7
MP24833-A – 55V, 3A, WHITE LED DRIVER
BLOCK DIAGRAM
2.4V
Figure 1: Functional Block Diagram
MP24833-A Rev. 1.02
www.MonolithicPower.com
3/29/2019
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2019 MPS. All Rights Reserved.
8
MP24833-A – 55V, 3A, WHITE LED DRIVER
OPERATION
The MP24833-A is a current-mode regulator.
The error amplifier (EA) output voltage is
proportional to the peak inductor current.
At the beginning of a cycle, the MOSFET is off.
The EA output voltage is higher than the current
sense amplifier output, and the current
comparator’s output is low. The rising edge of
the CLK signal sets the RS flip-flop. The CLK
frequency is the operating frequency. The flipflop output turns on the MOSFET that connects
SW and the inductor to the input supply.
The current sense amplifier detects and
amplifies the rising inductor current. The PWM
comparator compares the output of the EA
against the sum of the ramp compensator and
the current sense amplifier. When the sum of
the current sense amplifier output and the slope
compensation signal exceeds the EA output
voltage, the RS flip-flop resets, and the
MOSFET turns off. The external Schottky
rectifier diode (D) conducts the inductor current.
If the sum of the current sense amplifier output
and the slope compensation signal does not
exceed the EA output throughout the cycle,
then the falling edge of the CLK resets the flipflop.
The output of the EA integrates the voltage
difference between the feedback and the 0.2V
reference. The EA output increases when the
FB voltage is less than 0.2V. Since the EA
output voltage is proportional to the peak
inductor current, the increase in the EA output
voltage also increases the current delivered to
the output.
Soft Start (SS)
When the MP24833-A is enabled and VDD
exceeds the UVLO threshold, switching begins.
The soft start is not active when VFB - VSS is
lower than half of VREF, which is useful for
charging the output capacitor quickly. At the
same time, the current limit is folded to half.
Once VFB - VSS rises up to half of VREF, the soft
start begins and forces the internal reference
input of the EA to rise up from ⅔ of VREF slowly.
The current limit also recovers the normal value.
The soft-start function can make the duty cycle
extend slowly to limit current overshoot at startup.
Open-LED Protection
The OVP pin is used for open-LED protection
and monitors the output voltage through a
voltage divider. If the LED is open, there is no
voltage on FB. The duty cycle increases until
VOVP - VSS reaches the protection threshold set
by the external resistor divider. The top switch
turns off until VOVP - VSS decreases sufficiently.
Dimming Control
The MP24833-A allows for both DC and PWM
dimming. When the voltage on EN/DIM
(reference to INGND) is less than 0.6V, the chip
turns off.
For analog dimming, the LED current is
dependent linearly on the EN/DIM voltage
range between 0.67V and 1.35V, from 0% to
100%. An EN/DIM voltage higher than 1.35V
generates the maximum LED current.
For PWM dimming, VEN/DIM - VINGND must
exceed 1.5V. Use a PWM frequency in the
range of 100Hz to 2kHz for good dimming
linearity. For combined analog and PWM
dimming, apply a PWM signal with an amplitude
from 0.67V to 1.35V to EN/DIM.
Output Short-Circuit Protection (SCP)
The MP24833-A features output short-circuit
protection (SCP). When the output is shorted to
VSS, the voltage on OVP drops below 0.2V,
and FB senses no voltage (