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MAX25610A/MAX25610B
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
General Description
Benefits and Features
The MAX25610A/MAX25610B are fully synchronous
LED drivers that provide constant output current to
drive high-power LEDs. The MAX25610A/MAX25610B
integrate two 60mΩ power MOSFETs for synchronous
operation, minimizing external components. Flexible
configuration supports buck, inverting buck-boost, and
boost conversion. The devices incorporate currentmode control that provides fast transient response and
eases loop stabilization. The MAX25610A/MAX25610B
include cycle by cycle current limiting, output overvoltage
protection (OVP), open-string protection, output shortcircuit protection (SCP), and thermal shutdown.
In LED driver applications, the MAX25610A/MAX25610B
provide analog dimming of the LED current through the
REFI pin, and PWM dimming through the PWMDIM
pin. Switching is enabled when PWMDIM is high, and
disabled with both MOSFETs off when PWMDIM is low.
Analog programming of the PWMDIM pin enables the
built-in digital dimming function, with dimming frequency
selected by the PWMFRQ pin.
The MAX25610A/MAX25610B include two 5V regulators.
A regulated 5V between VCC and AGND is used for IC
bias, REFI and PWMFRQ programming. Another low
current regulated 5V between VEE and INN is used for
analog PWMDIM and FLT pullup. Both PWMDIM and
FLT reference INN for easy system interface. Switching
frequency is internally set at 400kHz for the MAX25610A
and 2.2MHz for the MAX25610B. The devices have builtin spread spectrum to reduce EMI noise. External and
internal current sense are supported, with ±3% and ±6%
respective LED current accuracy.
The MAX25610A/MAX25610B are well-suited for
automotive applications requiring high voltage input and
can withstand load dump events up to 40V. The devices
can also be used as a DC-DC converter using the
FB input as feedback for the output voltage divider.
The MAX25610A/MAX25610B are available in thermally
enhanced 16-pin TSSOP-EP and 16-pin TQFN packages.
They are specified to operate over the -40ºC to +125ºC
automotive temperature range.
Applications
●● Automotive Lighting Applications
●● Industrial Lighting Applications
19-100449; Rev 5; 4/19
●● Automotive Ready: AEC-Q100 Qualified
●● Integration Minimizes BOM to Save Space and Cost
• Wide input Voltage Range from 5V to 36V in BuckBoost LED Driver Applications
• 2.2MHz Switching Frequency Option Reduces
Inductor Size
• Internal Current-Sense Option Reduces Cost
• Integrated High and Low-Side Switching MOSFETs
• PWM Dimming with an Analog Control Voltage
Minimizes Additional Components for Dimming
●● Wide Dimming Ratio Allows High Contrast Ratio
• Analog and PWM Dimming
●● Multi-Topology Architecture Provides Flexibility
• Buck LED Driver for 1-to-2 LEDs When Operating
of Automotive Battery Applications
• Inverting Buck-Boost LED Driver for 3-to-5 LEDs
When Operating from Automotive Battery
Applications
●● Protection Features and Wide Temperature Range
Increase System Reliability
• -40°C to +125°C Operating Temperature Range
• Short-Circuit, Overvoltage, and Thermal Protection
• FLT Flag for Fault Indication
Ordering Information appears at end of data sheet.
Simplified Application Circuit
VIN+
CIN2
CIN
VIN-
IC-GND
PWM or
ANALOG
DIMMING
CVEE
INP
BST
INN
LX
LX
VEE
OUT
L
MAX25610A
LED1
RPWMFRQ
ROUT2
PGND
FB
VCC
COMP
COUT
LEDn
VCC
100kΩ
CCOMP
REFI
AGND
BATTERY GND
VIN-
ROUT1
PWMDIM
OPEN-DRAIN
FLT
FAULT
CPWMFRQ
PWMFRQ
CVCC
RREFI
CBST
RCOMP
IC-GND
DOMAIN
MAX25610A/MAX25610B
Absolute Maximum Ratings
INP to PGND..........................................................-0.3V to +40V
INP to LX................................................................-0.3V to +40V
LX to PGND...........................................................-0.3V to +40V
VCC to AGND........................................................-0.3V to +6.0V
BST to LX..............................................................-0.3V to +6.0V
INP to INN..............................................................-0.3V to +40V
PGND to AGND.....................................................-0.3V to +0.3V
PWMFRQ, OUT to AGND............................-0.3V to VCC + 0.3V
REFI, COMP to AGND.................................-0.3V to VCC + 0.3V
FB to AGND...........................................................-0.3V to +16V
INN to AGND..........................................................-0.3V to +24V
VEE, PWMDIM to INN...........................................-0.3V to +6.0V
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
FLT to INN.............................................................-0.3V to +6.0V
Short-Circuit Between VCC and AGND......................Continuous
Continuous Power Dissipation (Multilayer Board) TSSOP-EP
(TA = +70°C, derate 26.1mW/°C above +70°C).........2088mW
Continuous Power Dissipation (Multilayer Board) TQFN-EP
(TA = +70°C, derate 33.3mW/°C above +70°C).........2667mW
Operating Temperature Range.......................... -40°C to +125°C
Junction Temperature.......................................................+150°C
Storage Temperature Range............................. -40°C to +150°C
Soldering Temperature (reflow)........................................+260°C
LX Continuous RMS Current (per pin)..................................1.5A
INP, PGND Continuous RMS Current...................................2.5A
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these
or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
Package Information
TSSOP
PACKAGE CODE
U16E+3C
Outline Number
21-0108
Land Pattern Number
90-0120
Thermal Resistance, Single-Layer Board:
Junction-to-Ambient (θJA)
47°C/W
Junction-to-Case Thermal Resistance (θJC)
3°C/W
Thermal Resistance, Four Layer Board:
Junction-to-Ambient (θJA)
38.3°C/W
Junction-to-Case Thermal Resistance (θJC)
3°C/W
TQFN
PACKAGE CODE
T1655Y+3C
Outline Number
21-100279
Land Pattern Number
90-0072
Thermal Resistance, Single-Layer Board:
Junction-to-Ambient (θJA)
48°C/W
Junction-to-Case Thermal Resistance (θJC)
2°C/W
Thermal Resistance, Four-Layer Board:
Junction-to-Ambient (θJA)
30°C/W
Junction-to-Case Thermal Resistance (θJC)
2°C/W
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”,
“#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board.
For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
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Maxim Integrated │ 2
MAX25610A/MAX25610B
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
Electrical Characteristics
(INP = 12V, INN = AGND = PGND, PWMDIM = INN, Limits are 100% tested at TA = 25°C and TA = 125°C. Limits over the operating
temperature range and relevant supply voltage range are guaranteed by design and characterization from TA = -40°C to TA = 125°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
INPUT SUPPLY
t < 1s
Input Supply Voltage Range
VINP
Buck-boost
configuration,
PWMDIM = VEE
40
External digital mode
PWM dimming
5
36
Internal analog mode
PWM dimming
7.5
36
8.3
36
Buck configuration
Quiescent Current
IINQ
PWMDIM = INN
VINP = 12V
4
6
PWMDIM = INN
VINP = 36V
5
7
Buck mode
UV Lockout
Buck-boost mode
Switching Current
ISW
V
mA
Rising threshold
7.5
8
8.3
Falling threshold
7.25
7.75
8.25
Rising threshold
4.2
4.45
5
Falling threshold
4.1
4.35
4.6
MAX25610A
PWMDIM = VEE
VINP = 12V
12
20
MAX25610B
PWMDIM = VEE
VINP = 12V
35
MAX25610A
PWMDIM = VEE
VINP = 33V
20
V
mA
VCC REGULATOR
Output Voltage
VCC
Dropout Voltage
VCC_DROP
Short-Circuit Current Limit
IVCC_SC
VCC Current Limit
5.5V < VINP < 32V, IVCC = 0mA–20mA
4.89
VINP = 5V, IVCC = 20mA
5.00
5.1
V
0.2
0.35
V
VCC shorted to AGND
15
40
100
mA
VCC = 4.8V
30
100
200
mA
5.5V < VINP < 33V, IVEE = 2mA
4.7
5.00
5.3
V
VEE REGULATOR
Output Voltage
VEE
Dropout Voltage
VEE_DROP
VINP = 5V, IVEE = 3mA
0.1
0.35
V
VEE UVLO Rising
VEE_UVLOR
INP rising
4.1
4.4
4.6
V
VEE UVLO Falling
VEE_UVLOF
INP Falling
4.0
4.25
4.5
V
IVEE_SC
VEE shorted to INN
10
26
60
mA
High-Side MOSFET RDSON
RON_HS
ILX = 1A (0.5A per LX pin) (Note 1)
0.06
0.130
Ω
Low-Side MOSFET RDSON
RON_LS
ILX = 1A (0.5A per LX pin) (Note 1)
0.06
0.130
Ω
4.25
4.84
A
+5.0
μA
Short-Circuit Current Limit
INTERNAL MOSFETS
High-Side MOSFET Current
Limit Threshold
LX Leakage
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(Note 2)
ILX,LEAK
PWMDIM = INN
3.55
VINP = 40V,
VLX = 0V or 40V,
TA = +25°C
-5.0
Maxim Integrated │ 3
MAX25610A/MAX25610B
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
Electrical Characteristics (continued)
(INP = 12V, INN = AGND = PGND, PWMDIM = INN, Limits are 100% tested at TA = 25°C and TA = 125°C. Limits over the operating
temperature range and relevant supply voltage range are guaranteed by design and characterization from TA = -40°C to TA = 125°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX25610A
370
400
430
kHz
MAX25610B
2
2.18
2.36
MHz
INTERNAL OSCILLATOR
Switching Frequency
Minimum On-Time
Maximum Duty Cycle
fSW
tON_MIN
DMAX
Dithering off
MAX25610A only
100
MAX25610B only
56
85
91
94
MAX25610A only
89
Frequency Dither
+6
ns
%
%
OVERVOLTAGE
Overvoltage Threshold
Rising
INPSTOP
Buck-boost mode
INP rising
33
34.5
36
V
Overvoltage Threshold
Falling
INPSTART
Buck-boost mode
INP falling
32
33.3
34.5
V
200
1000
Hz
-10
+10
%
PWM DIMMING (PWMDIM)
Set with external RC on PWMFRQ pin,
Ramp Frequency
f DIM =
PWM Frequency Accuracy
DIM Comparator Offset
Voltage
3.33 × 10 −3
R PWMFRQ × C PWMFRQ
Ideal external resistor and capacitor
VDIMOFS
Voltages referred to INN
DIM Comparator for 100%
Duty Cycle
0.2
V
3.3
PWM Duty Cycle Accuracy
PWMDIM Logic-Level Low
VPWMDIM_H
PWMDIM Logic-Level High
VPWMDIM_L
V
VPWMDIM - VINN = 0.9V
23.5
25
26.5
VPWMDIM - VINN = 2.3V
72
75
78
0.4
2.0
%
V
V
ANALOG DIMMING (REFI)/INTERNAL SENSE
Buck mode 8.5V
< VINP - VPGND
< 33V
Current Regulation
Buck mode 8.5V
< VINP - VPGND <
33V
Buck mode 8.5V
< VINP - VPGND
< 33V
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RREFI = 4.59kΩ
(Note 3) (Note 4)
2.75
2.85
2.95
RREFI = 8.76kΩ
(Note 3)
1.4325
1.5
1.5675
RREFI = 21.8kΩ,
TJ = 0°C to +125°C
(Note 3)
0.564
0.6
0.636
RREFI = 21.8kΩ,
TJ = -40°C to +125°C
(Note 3)
0.550
0.6
0.650
A
Maxim Integrated │ 4
MAX25610A/MAX25610B
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
Electrical Characteristics (continued)
(INP = 12V, INN = AGND = PGND, PWMDIM = INN, Limits are 100% tested at TA = 25°C and TA = 125°C. Limits over the operating
temperature range and relevant supply voltage range are guaranteed by design and characterization from TA = -40°C to TA = 125°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
VREFI = 0.4V, 8.5V <
VINP - VPGND < 31V
28.1
30
31.8
mV
VREFI = 1.2V, 8.5V <
VINP - VPGND < 31V
0.147
0.15
0.153
V
ANALOG DIMMING (REFI)/EXTERNAL SENSE
Current-Sense Regulation
Voltage (External Sense
Resistor)
FB connected to
external sense
resistor to AGND
Input Bias Current
REFIIN
VREFI = 0V to VCC
REFI Zero-Voltage
Threshold
REFIZC
Rising threshold
REFI Clamp Voltage
20
nA
0.165
0.18
0.195
V
REFICL
1.273
1.3
1.328
V
gM
1.2
1.8
2.4
mS
0.142
0.163
0.175
V/μs
CONTROL LOOP
Error Amplifier Transconductance
Slope Compensation
SlopeC
Buck mode, MAX25610A
SHRTR
OUT rising
140
170
200
SHRTF
OUT falling
120
150
180
OVR
OUT rising
2.85
3
3.15
OVF
OUT falling
2.75
2.9
3.05
OUT PIN
Short Threshold
Overvoltage Threshold
OUT Leakage
OUTLKG
mV
V
100
nA
200
mV
1
μA
FAULT FLAG
Output Voltage Low
VOL_FLT
Referred to INN
ILOAD = 5mA
Fault Leakage Current
FLTLKG
Referred to INN
VFLT = 5V
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
Note
Note
Note
Note
TSHUTDOWN Temperature rising
THYS
165
°C
10
°C
1: Bondwires are not tested in production. Estimated maximum bondwire resistance is 20mΩ.
2: Extrapolated from ATE measurements at 1.9A and 0.5A.
3: DC accuracy measured on ATE.
4: Extrapolated from ATE measurements at 1A and 0.6A.
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Maxim Integrated │ 5
MAX25610A/MAX25610B
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
Typical Operating Characteristics
(VINP = 13.5V, PWMDIM = VEE, TA = +25°C, unless otherwise noted.)
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Maxim Integrated │ 6
MAX25610A/MAX25610B
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
Typical Operating Characteristics (continued)
(VINP = 13.5V, PWMDIM = VEE, TA = +25°C, unless otherwise noted.)
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Maxim Integrated │ 7
MAX25610A/MAX25610B
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
VEE
INN
PWMDIM
COMP
OUT
FB
REFI
TOP VIEW
PWMFRQ
Pin Configurations
16 15 14 13 12 11 10
9
MAX25610A
MAX25610B
EP
5
VCC
PGND
INP
LX
6
7
8
FLT
4
BST
3
LX
2
COMP
PWMFRQ
PWMDIM
TSSOP
OUT
TOP VIEW
1
AGND
+
12
11
10
9
FB 13
MAX25610A
MAX25610B
REFI 14
AGND 15
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2
3
4
LX
PGND
1
LX
+
INP
VCC 16
8
INN
7
VEE
6
FLT
5
BST
TQFN
5mm x 5mm
Maxim Integrated │ 8
MAX25610A/MAX25610B
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
Pin Description
PIN
NAME
REF
SUPPLY
FUNCTION
TSSOP
TQFN
1
15
AGND
2
16
VCC
3
1
PGND
4
2
INP
Input Positive Supply. INP is internally connected to the drain terminal of highside power FET. Bypass this pin to PGND with a ceramic capacitor close to
the pin.
5, 6
3, 4
LX
Switching Node. Connect the output inductor to these pins with wide traces.
Place the inductor as close as possible to the pins.
7
5
BST
High-Side Power Supply for High-Side Gate Drive. Place a 0.1μF ceramic
capacitor from this pin to LX.
8
6
FLT
Active-Low, Open-Drain Fault Indicator Output. Connect through an external
pullup resistor to an external supply with the desired level. This pin can be left
open if it is not used. See the [[Fault Handling]] section for more information.
9
7
VEE
Auxiliary 5V Regulator. Bypass this pin to INN with a minimum 1μF ceramic
capacitor.
10
8
INN
Ground Side of Input Supply. Connect this pin to PGND when used as a buck
converter.
11
9
PWMDIM
Analog Ground. Connect control loop compensation and other small-signal
components to this ground. Connect to PGND at a single point.
Main 5V Internal LDO. Bypass this pin to AGND with a minimum 0.1μF ceramic capacitor. Bypass this pin to PGND with a minimum 1μF ceramic capacitor.
Power Ground Reference Node. PGND is connected internally to the source
terminal of internal low-side power MOSFET.
Dimming Control Input. Connect PWMDIM to an external PWM signal for
PWM dimming. For analog voltage-controlled PWM dimming, connect
PWMDIM to a resistive voltage-divider from VEE to INN. The duty cycle is
given by D =
(VPWMDIM − 0.205) . Connect PWMDIM to INN to turn off the
2.8
LEDs. Connect PWMDIM to VEE for 100% duty cycle.
Frequency Programming for PWM Dimming Function. Connect PWMFRQ to
the junction of an RC from VCC to AGND. Dimming frequency is given by
12
10
PWMFRQ
3.33 x 10−3
fDIM = R
. Do not connect any other component or device
PWMFRQ x CPWMFRQ
VCC
to this pin.
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Maxim Integrated │ 9
MAX25610A/MAX25610B
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
Pin Description (continued)
PIN
REF
SUPPLY
NAME
FUNCTION
11
COMP
Compensation Network Connection. For proper compensation, connect a suitable RC network from COMP to AGND and a capacitor from COMP to AGND.
14
12
OUT
15
13
FB
TSSOP
TQFN
13
Overvoltage Sense. Connect OUT to a resistor divider from LED+ to AGND.
The typical overvoltage threshold is 3V.
LED Current-Sense Input. Connect FB to external LED current-sense resistor
for external sense of LED current. Connect FB to VCC through a 100kΩ resistor to enable internal current-sense regulation.
Analog Dimming Control Input. In external current-sense mode, the voltage at
REFI sets the LED current level when VREFI < 1.25V. This voltage reference
can be set using a resistive divider from the VCC output. For VREFI > 1.25V
an internal reference sets the LED current. The LED current with external
16
14
REFI
current sense is given by ILED =
(VREFI − 0.2) . In internal current-sense
6.67RLED
mode, a resistor connected between REFI and AGND sets the current
regulation. The LED current is given by ILED = 13125 .
RREFI
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Maxim Integrated │ 10
MAX25610A/MAX25610B
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
Functional Diagrams
OUT
VEE
FLT
INP
VEE
REG
PWMDIM
DETECTOR
PWMFRQ
FREQUENCY
GENERATOR
OPEN/
SHORT DET THERMAL
PWM
GENERAT OR
MUX
BIAS
INP
ISENSE
LX
OSC
MAX25610A
MAX25610B
BG
AGND
+
PGND
DLL +
FILTER
PWM
CSA
MUX
ISNS
ISNS
OCP
VCC
REG
SLOPE
BST
DIM
DRIVER
INP
VCC
INN
EAMP
CSA
PGND
FB
FB
CONTROL
COMP
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REFI
Maxim Integrated │ 11
MAX25610A/MAX25610B
Detailed Description
The MAX25610A/MAX25610B are fully synchronous LED
drivers that provide constant output current to drive highpower LEDs. The MAX25610A/MAX25610B integrate
two 60mΩ power MOSFETs for synchronous operation,
minimizing external components. Flexible configuration
supports buck, inverting buck-boost and boost conversion.
The device incorporates current-mode control that provides
fast transient response and eases loop stabilization. The
MAX25610A/MAX25610B include cycle by cycle current
limiting, output overvoltage protection (OVP), open-string
protection, output short-circuit protection (SCP), and
thermal shutdown.
In LED driver applications, the MAX25610A/MAX25610B
provide analog dimming of the LED current through the
REFI pin and PWM dimming through the PWMDIM pin.
Switching is enabled when PWMDIM is high and disabled
with both MOSFETs off when PWMDIM is low. Analog
programming of the PWMDIM pin enables the built-in
digital dimming function, with dimming frequency selected
by the PWMFRQ pin.
The MAX25610A/MAX25610B include two 5V regulators.
A regulated 5V between VCC and AGND is used for
IC bias, as well as REFI and PWMFRQ programming.
Another low current regulated 5V between VEE and
INN is used for analog PWMDIM and FLT pullup. Both
PWMDIM and FLT reference INN for easy system
interface. Switching frequency is internally set at 400kHz
for the MAX25610A and 2.2MHz for the MAX25610B.
The devices have built-in spread spectrum to reduce EMI
noise. External and internal current sense are supported,
with ±3% and ±6% respective LED current accuracy.
The MAX25610A/MAX25610B are well-suited for automotive
applications that require high-voltage input and can
withstand load dump events up to 40V. The devices can
also be used as DC-DC converters using the FB input as
feedback for the output voltage divider. The MAX25610A/
MAX25610B are available in thermally enhanced 16-pin
TSSOP-EP and 16-pin TQFN packages. They are
specified to operate over the -40°C to +125°C automotive
temperature range.
Functional Operation
The MAX25160A/MAX25610B are fully synchronous,
monolithic, constant frequency peak current-mode
DC-DC LED drivers. These devices support both internal
and external current sensing of the LED current. Upon
power-up, the device detects the voltage level of the FB
pin to determine the current sense configuration. External
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Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
LED current sensing is configured by connecting the FB
pin to an external sense resistor in series with LED string.
The devices regulate the current to the programmed
voltage at the REFI pin. Internal LED current sensing is
selected by connecting the FB pin to VCC through a 100kΩ
resistor. The devices use an integrated current sense of
the low-side power FET and regulate that current to the
programmed current at the REFI pin.
The fixed-frequency oscillator turns on the internal highside power FET at the beginning of each clock cycle.
Current in the inductor then increases until the internal
PWM comparator trips and turns off the high-side power
FET. When the high-side power FET turns off, the
synchronous low-side power FET turns on until the next
clock cycle begins.
In external LED current sensing, the FB voltage is amplified
by a factor of 6.67 and fed to the inverting input of a
transconductance amplifier, while the REFI voltage is
fed to the noninverting input. In internal current sensing,
the transconductance amplifier compares the current
programmed at REFI against the current sensed across
the low-side power FET. In both cases, the error signal
at the inputs of the transconductance amplifier generate
a proportional current out the COMP pin. COMP is
externally compensated by a resistor and capacitor
network. The compensated COMP voltage is fed to the
noninverting input of a PWM comparator. The inverting
input of the PWM comparator is a signal that represents
the current on the high-side power FET summed with a
saw-toothed ramp.
The devices also include a PWMDIM dimming input that
is used for PWM dimming of the LED current. When
this signal is low, both the high-side and low-side power
FETs are turned off. When the PWMDIM signal goes
high the LED current regulation starts. The rising edge
of the PWMDIM signal also restarts the internal oscillator
to allow the high-side power FET to be turned on at the
same time as the rising edge of the PWMDIM signal. This
provides consistent dimming performance at low dimming
duty cycles. Analog programming of the PWMDIM pin
operates in the same way as described above, except
that it uses an internal PWM clock with dimming frequency
selected by the PWMFRQ pin.
Mode Selection
The devices can operate in two modes. Connect a 2.49kΩ
resistor from VCC to PWMFRQ pin for operation in buck
mode. Connect a 17.8kΩ resistor from VCC to PWMFRQ
pin to operate in buck-boost or boost mode.
Maxim Integrated │ 12
MAX25610A/MAX25610B
LED Current Sense
The device can use both internal and external current
sense for the LED current. For external LED current
sense a resistor is connected between the cathode of
the last LED in the string and ground. The FB pin is
connected to the cathode of the LED string. The regulated
LED current is given by:
(VREFI − 0.2)
ILED = 6.67R
LED
where:
VREFI is in volts,
RLED is in ohms.
For internal current sense, connect FB pin to VCC with
a 100kΩ resistor. The LED current is now sensed by
the current flowing in the bottom MOSFET. When using
internal current sense, the REFI pin should only have a
resistor to AGND. The LED current is then given by:
13125
ILED = R
REFI
Analog Dimming
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
This regulator can provide a maximum of 2mA to external
circuits. Bypass VEE to INN with a minimum 1μF ceramic
capacitor as close as possible to the devices. The VEE
regulator features an output UVLO that stops switching of
the MAX25610A/MAX25610B when the VEE voltage goes
below the typical UVLO threshold of 4.25V.
BST Supply
The BST pin provides the drive voltage to the high-side
switching MOSFET. Connect a 0.1μF ceramic capacitor
from this pin to the LX pin. Place the capacitor as close
as possible to BST pin. The BST capacitor is charged
from an internal diode from VCC when LX goes low.
Input UVLO
The devices have an integrated UVLO that disables
switching when the voltage from INP to INN falls below an
internal threshold. When the device is set for operation in
the buck-boost mode switching is enabled when the input
voltage exceeds 4.5V(typ) and disabled when the voltage
drops below 4V (typ). If the device is set for operation
in the buck mode, the switching is enabled when the
voltage exceeds 8.0V (typ) and is disabled when the
voltage drops below 7.75V (typ).
The device has an analog dimming control input pin
(REFI). In external sensing mode, the voltage at REFI
sets the LED current level when REFI ≤ 1.2V. For higher
voltages, REFI is clamped to 1.25V (typ). The LED
current is guaranteed to be at zero when the REFI voltage
is at or below 0.18V (typ). The LED current can be linearly
adjusted from zero to full scale for REFI voltages in the
range of 0.2V to 1.2V.
Cycle-by-Cycle Current Limit
In internal sensing an external resistor from REFI pin to
ground is used to program the LED current. The REFI
pin voltage is regulated to 1.25V in this mode. The LED
current is then given by:
The devices incorporate slope compensation to prevent
sub-harmonic oscillations for duty cycles exceeding 50%.
When the device is configured for buck mode the slope
compensation ramp rate is 562mA/μs for the MAX25610A
and 2.9A/μs for the MAX25610B. When configured as a
buck-boost converter, the slope compensation ramp is
proportional to the output voltage. The slope compensation
ramp rate for the buck-boost converter is (slope =
0.078VOUT)A/μs in the MAX25610A.
13125
ILED = R
REFI
VCC Regulator
The devices feature a 5V linear regulator (VCC) that is
powered by the input voltage on INP. The VCC regulator
provides power to all the internal logic, control circuitry,
and the gate drivers. Bypass VCC to AGND with a
minimum of 0.1μF ceramic capacitor as close as possible
to the devices. Bypass VCC to PGND with a minimum of
1μF ceramic capacitor as close as possible to the device.
VEE Regulator
The devices include a 5V VEE regulator that generates
a 5V supply referenced to INN. This regulator powers
the internal PWM dimming and fault indication circuitry.
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The MAX25610A/MAX25610B implement a cycle-bycycle current limit on the internal high-side power switch.
If the peak current in the high-side switch exceeds 4.25A
(typ), the switch is turned off immediately. The high-side
switch turns on again at the start of the next clock cycle.
Slope Compensation
Spread Spectrum
The devices use a triangular spread-spectrum modulation
technique to reduce the EMI for frequencies less than
30MHz. The spread spectrum is internally set at +6%. The
switching frequency increases linearly from a low of 0.94
times the programmed frequency to a high of 1.06 times
the programmed frequency. The modulation frequency
of the triangular pattern is 0.2% of the programmed
switching frequency. For the MAX25610A, the modulation
frequency is 800Hz. For the MAX25610B, the modulation
frequency is 4.5kHz.
Maxim Integrated │ 13
MAX25610A/MAX25610B
Overvoltage Protection
If the voltage from INP to PGND exceeds 34.5V (typ) in
the buck-boost and boost configuration, the LED current
regulation is disabled and both the internal MOSFETs are
turned off. Switching is enabled once the voltage from INP
to PGND goes below 33.3V (typ). In the buck mode, the
devices keep switching at all input voltages above input
UVLO.
Error Amplifier
An internal transconductance amplifier with a
transconductance of 1800μS is used by the control loop
in the MAX25610A/MAX25610B to regulate the LED
current. In external LED current sensing, the FB voltage is
amplified by a factor of 6.7 and fed to the inverting
input of a transconductance amplifier, while the REFI
voltage is fed to the noninverting input. In internal current
sensing, the transconductance amplifier compares the
current programmed at REFI against the current sensed
across the low-side power FET. In both cases, the error
signal at the inputs of the transconductance amplifier
generate a proportional current out the COMP pin. COMP
is externally compensated by a resistor and capacitor
network. The compensated COMP voltage is fed to the
non-inverting input of a PWM comparator. The inverting
input of the PWM comparator is a signal that represents
the current on the high-side power FET summed with a
with a slope compensation ramp.
When the PWM dimming signal is low the COMP pin
is internally disconnected from the output of the error
amplifier. When the dimming signal is high, the output of
the error amplifier is connected to COMP. This enables
the compensation capacitor to hold the charge when
the dimming signal has turned off the internal switching
MOSFETs. To maintain the charge on the compensation
capacitor CCOMP, the capacitor should be a low-leakage
ceramic type. When the internal dimming signal is
enabled, the voltage on the compensation capacitor forces
the converter into steady state almost instantaneously.
PWM Dimming
The PWMDIM pin is used to enable/disable the internal
switching MOSFETs, and also for pulse width modulated
dimming. When PWMDIM is high (> 2VMIN), the devices
enable the internal oscillator, and MOSFET switching
resumes. This synchronizes operation and eliminates
flicker during low pulse widths. When PWMDIM is low
(< 0.4VMAX), current regulation is stopped. Both internal
MOSFETS are three-stated, and the output of the error
amplifier is disconnected from the external components
on the COMP pin.
The PWMDIM pin is also used for PWM dimming in two
modes, one programmed with an analog voltage, and the
other using a digital signal.
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Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
Internal PWM Dimming Frequency Generator
An internal PWM frequency generator is implemented
with an RC connected at the PWMFRQ pin. The resistor
RPWMFRQ is connected from PWMFRQ to VCC and a
capacitor CPWMFRQ is connected from PWMFRQ to
AGND. RPWMFRQ needs to be 2.49kΩ when the device is
used in buck mode and 17.8kΩ when used in buck-boost
or boost mode. The ceramic capacitor from PWFRQ
to AGND should be in the range of 300pF to 6.8nF. It
is recommended to use ceramic capacitors with low
tolerances for accurate frequency programming. COG
and NPO dielectrics are preferred.
The internal PWM dimming frequency is given by:
f DIM =
3.33 × 10 −3
R PWMFRQ × C PWMFRQ
Table 1 lists some examples for the dimming frequency.
For external digital PWM dimming use a minimum
capacitance of 220nF for CPWMFRQ.
Analog Mode PWM Dimming
If an analog control signal is applied to PWMDIM, the
device compares the DC input to an internally generated
ramp to pulse-width-modulate the LED current. The ramp
frequency is set by an RC network on the PWMFRQ pin.
The output-current duty cycle is linearly adjustable from
0% to 100% (0.2V < VPWMDIM < 3V). The PWM dimming
duty cycle in analog mode is given by:
D=
(VPWMDIM − 0.205)
2.8
where VPWMDIM is the voltage applied to PWMDIM in
volts.
Table 1. PWMDIM Frequency Selection
MODE
Buck
BuckBoost or
Boost
RPWMFRQ
(KΩ)
2.49
17.8
CPWMFRQ
PWMDIM
FREQUENCY (HZ)
1.2nF
1114
2.7nF
495
3.3nF
405
4.3nF
311
6.8nF
197
300pF
624
360pF
520
470pF
398
620pF
302
910pF
206
Maxim Integrated │ 14
MAX25610A/MAX25610B
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
Digital Mode PWM Dimming
If a TTL-level digital input signal is applied to PWMDIM
pin, the duty cycle determines the dimming ratio and the
frequency is set by the digital input pulse frequency.
Once an LED open is detected, FLT is asserted low, the
current regulation is stopped, and the internal MOSFETs
go into a high-impedance state. This latch-off condition
persists until the OUT pin voltage drops below 2.9V (typ).
Thermal Protection
Fault Behavior Internal Sensing
The devices feature thermal protection. When the junction
temperature exceeds +165°C, the internal MOSFETs stop
switching resulting in the reduction in power dissipation
in the device. The part returns to regulation once the
junction temperature falls below +155°C. Both the VCC
and VEE regulators continue to regulate even during
thermal shutdown.
LED Short Fault
Fault Flag
2) REFI resistor < 280kΩ (typ)
During internal current sensing, the devices can detect a
short between the anode and the cathode of LED string
or between anode of the LED string and PGND. The
following conditions need to be satisfied simultaneously to
detect and flag a SHORT fault:
1) OUT voltage < SHRT threshold (150mV, typ)
Fault Behavior External Sensing
3) End of startup blanking timer (650μs, typ)
LED Short Fault
Once an LED short is detected, the FLT flag is asserted
low. The current continues to be regulated even if the short
is between LED+ and LED- or between LED+ and PGND.
During external current sensing, the devices can detect
a short between the anode and the cathode of the
LEDs. The following conditions need to be satisfied
simultaneously to detect and flag an LED short fault:
1) OUT voltage < SHRT threshold (150mV, typ)
2) End of startup blanking timer (650μs, typ)
The startup timer is cumulative during dimming high phases;
the timer is suspended during dimming low phases.
The total cumulative on duration of successive dimming
pulses should exceed 650μs to activate fault detection.
Once an LED short is detected, the FLT flag asserts low.
Short-to-PGND Fault
During external current sensing, the devices can detect a
short between the anode of the LED string and the ground
terminal. The following conditions need to be satisfied at
the same time to detect and flag a PGND short fault:
LED Open Fault
During Internal current sensing, the devices can detect
an open circuit in the LED string. The following conditions
need to be satisfied simultaneously to detect and flag a
LED-OPEN fault:
1) OUT voltage > OV threshold (3V, typ)
Once LED open is detected, FLT is asserted low, the
current regulation is stopped, and the internal MOSFETs
go into a high-impedance state. This latch-off condition
persists until the OUT pin voltage drops below 2.9V (typ).
VEE UVLO Fault
The devices also feature an VEE undervoltage lockout
fault. When the VEE voltage goes below its UVLO level of
4.25V (typ), the fault flag FLT asserts low.
1) OUT voltage < SHRT threshold (150mV, typ)
Thermal Shutdown Fault
2) COMP > 3.4V (typ)
The FLT pin goes low when thermal shutdown is
activated.
3) End of startup blanking timer (650μs, typ)
Once an LED PGND short is detected, FLT is asserted
low, the current regulation is stopped, and the internal
power MOSFETs switch off. This latch-off condition
persists until power is recycled.
LED Open Fault
The devices can detect an open circuit on the LED string.
The following condition needs to be satisfied simultaneously
to detect and flag an LED open fault:
Exposed Pad
The device package features an exposed thermal pad
on its underside to use as a heat sink. This pad lowers
the package’s thermal resistance by providing a direct
heat-conduction path from the die to the PCB. Connect
the exposed pad and AGND together using a large pad
or ground plane, or multiple vias to the AGND plane layer.
1) OUT voltage > OV threshold (typ 3V)
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Maxim Integrated │ 15
MAX25610A/MAX25610B
Applications Information
Inductor
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
where:
VLED is the forward voltage of the LED string
The peak inductor current and the allowable inductor
current ripple determine the value and size of the output
inductor.
VINMIN is the minimum input supply voltage
In the buck LED driver, the average inductor current is
the same as the LED current. The peak inductor current
occurs at the maximum input line voltage where the duty
cycle is at the minimum:
In the buck-boost LED driver, the average inductor
current is equal to the input current plus the LED current.
Calculate the maximum duty cycle using the following
equation:
VLED
DMIN = V
INMAX
where:
VLED is the forward voltage of the LED string
VINMAX is the maximum input supply voltage
Actual voltages for the above can be determined once
component selection is completed.
DMAX =
VLED
(VLED + VINMIN)
with the variables being the same as defined in the
calculation of the boost configuration.
ILPK = ILED + 0.5 x ∆IL
For both boost and buck-boost configurations, use the
following equations to calculate the maximum average
inductor current (ILDC_MAX), peak-to-peak inductor
current ripple (∆IL), and the peak inductor current (ILPK)
in amperes:
The inductance value of inductor LBUCK is calculated as:
ILDC_MAX = ILED/(1 - DMAX)
The maximum peak-to-peak inductor ripple (∆IL) occurs
at the maximum input line. The peak inductor current is
given by:
LBUCK =
VINMIN × DMAX
fSW × ∆ IL
where:
fSW is the switching frequency.
For the MAX25610A, fSW is 400kHz and for the
MAX25610B fSW is 2.2MHz. Choose an inductor that has
a minimum inductance greater than the calculated value.
Boost and buck-boost configurations are similar in that
the total output voltage seen by the inductor is always
higher than the input voltage. The difference being that,
for the boost configuration, the total output voltage is
dependent on the total LED voltage, while for the buckboost configuration, the total output voltage is dependent
on the sum of the LED voltage and the input voltage.
In the boost converter, the average inductor current
varies with the line voltage. The maximum average
current occurs at the lowest line voltage.
For the boost converter, the average inductor current is
equal to the input current. Calculate the maximum duty
cycle using the following equation:
DMAX =
www.maximintegrated.com
Allowing the peak-to-peak inductor ripple to be ∆IL, the
peak inductor current is given by:
ILPK = ILDC_MAX + 0.5 x ∆IL
The inductance value of inductor LBOOST or LBUCKBOOST is calculated as:
L
=
VINMIN × DMAX
fSW × ∆ IL
where fSW is the switching frequency, VINMIN and ∆IL are
defined above. Choose an inductor that has a minimum
inductance greater than the calculated value. The current
rating of the inductor should be higher than ILPK at the
operating temperature.
To avoid sub-harmonic oscillation in the current-mode
controlled regulators when duty cycle is greater than
50%, the inductor value should be set to match the slope
compensation value at the designed frequency. The
selected inductor should satisfy the following condition.
2 × VOUT
SLOPE
>
L
>
VOUT
2 × SLOPE
(VLED − VINMIN)
VLED
Maxim Integrated │ 16
MAX25610A/MAX25610B
Input Capacitor
The input-filter capacitor bypasses the ripple current
drawn by the converter and reduces the amplitude of
high-frequency current conducted to the input supply. The
ESR, ESL, and bulk capacitance of the input capacitor
contribute to the input ripple. Use a low-ESR input
capacitor that can handle the maximum input RMS ripple
current from the converter. The input capacitors must also
be chosen such that the capacitors can withstand the
maximum expected input voltage with adequate design
margin.
In the buck configuration, the minimum value of the
input capacitance is given by:
ILED
CMIN > 4 × η × f
SW × △ VIN
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
Note that the DC bias on the capacitor can derate the
capacitance value. The capacitance value can also
change due to temperature. The selected capacitor
should have a capacitance that exceeds the minimum
required capacitance at the maximum operating voltage
and maximum operating temperature.
Output Capacitor
With adequate design margin, the output capacitors can
withstand the maximum operating output voltage. The
output voltage ripple (ΔVOUT) is a function of the output
capacitance, its ESR, and ESL. Ceramic output capacitors
have very low ESR and ESL so the output ripple in
ceramic capacitors are purely a function of the ripple
current and the capacitance.
In the case of the buck converter, the minimum value of
the output capacitance is given by:
where:
△ IL
CMIN > 8 × f
SW × △ VOUT
ILED is the maximum LED current
η is the efficiency
fSW is the switching frequency
ΔVIN is the acceptable input voltage ripple
For the buck-boost configuration, the minimum value of
the input capacitance is given by:
ILED × DMAX
CMIN > η × f
SW × △ VIN
where:
ΔIL is the peak to peak output ripple at the maximum input
voltage
ΔVOUT is the maximum allowable output ripple
In the case of the buck-boost converter, the minimum
value of the output capacitance is given by:
ILED × VOUT
CMIN > (V
INMIN + VOUT) × fSW × △ VOUT
where:
DMAX is the maximum duty cycle that occurs at low line
In the boost configuration, the minimum value of the input
capacitance is given by:
△ IL
CMIN > 4 × f
SW × △ VIN
where:
ΔIL is the peak to peak inductor ripple at low line.
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where:
VINMIN is the minimum input voltage
In the case of the boost converter, the minimum value of
the output capacitance is given by:
ILED × VOUT
CMIN > (V
INMIN + VOUT) × fSW × △ VOUT
Maxim Integrated │ 17
MAX25610A/MAX25610B
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
Compensation
Buck-Boost External Sense
Table 2 shows suggested values of inductor, Output
capacitor and compensation components for the buck
and buck-boost configurations.
Loop gain equation is given by:
Buck External Sense
The loop gain equation is given by:
The right half plane zero for a Buck-Boost is given by:
FRHP
VLED × (1 − D)
=
2
2π × ILED × L × D2
Where:
where:
GM is the transconductance of error amplifier = 1.8mS
VLED is the voltage across the LED string
GCS is transconductance from comp pin to peak inductor
current = 3.33
D is the maximum duty cycleVIN is the Input Voltage VOUT
is the LED string voltage taken positive.
ZCOMP is the impedance of RCOMP in series with CCOMP
RLED is the dynamic resistance of LED
The unity gain frequency is chosen 1/6th of FRHP.
Choose:
ZOUT is the output impedance which is the parallel impedance of RSENSE + RLED with COUT
Choose:
RCOMP =
RCOMP
1
2π × FP × CCOMP
=
where:
1
2π × FP × CCOMP
FP is load pole frequency
FP
=
2π ×
(
1
RSENSE + RLED
)
× COUT
CCOMP value is:
Where:
FP is the Load pole frequency
Fu is the unity gain frequency, choose Fu = 40kHz
The RCOMP and CCOMP values are given in Table 2 for a
typical 1 or 2 LED application.
Buck Internal Sense
The compensation component values do not depend on
the output pole. For internal sensing applications in buck
mode set:
CCOMP
=
GM × VIN × GCS
2π ×
(VIN
× 6.67 × RSENSE
+ 2 × VOUT
)
× FU
FU is the unity gain frequency
The RCOMP and CCOMP values are given in Table 2 for a
typical 2 LEDs application.
RCOMP = 0Ω
CCOMP = 100nF
Table 2. Recommended Components—Various Configurations
PART NAME
CCOMP (NF)
RCOMP
(Ω)
COUT (ΜF)
Buck—External Current Sense
MAX25610A
22
75
2.2
22
Buck—External Current Sense
MAX25610B
22
75
2.2
4.7
Buck—Internal Current Sense
MAX25610A
100
0
2.2
22
Buck-Boost—External Current Sense
MAX25610A
220
100
20
33
Buck-Boost—Internal Current Sense
MAX25610A
220
62
20
33
CONFIGURATION
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LOUT (ΜH)
Maxim Integrated │ 18
MAX25610A/MAX25610B
Buck-Boost Internal Sense
The compensation component values do not depend on
the output pole.
CCOMP =
GM
2π × FU
Where:
FU is the unity gain frequency = 1/6th of FRHP.
Choose:
RCOMP
=
1
2π × CCOMP × 12kHz
The RCOMP and CCOMP values are given in Table 2 for a
typical 4 LED application.
PCB Layout Guidelines
For proper operation and minimum EMI, use the following
PCB layout guidelines:
●● All connections carrying pulsed currents must be
very short and as wide as possible. The inductance
of these connections must be kept to an absolute
minimum due to the high di/dt of the currents. Since
inductance of a current carrying loop is proportional
to the area enclosed by the loop, if the loop area is
made very small, inductance is reduced. Additionally,
small current loop areas reduce radiated EMI.
●● Place a 0603 0.1μF ceramic capacitor between INP
and PGND. Also place 2x 10μF ceramic capacitors
as close as possible between INP and PGND. These
capacitors provide the high-frequency switching
currents to the internal MOSFETs and their drivers.
In case of the buck-boost topology, add additional
capacitance between INP and INN.
●● Place a minimum 1μF ceramic bypass capacitor
between VCC and PGND and another minimum
0.1μF ceramic capacitor between VCC and AGND.
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Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
●● Place a minimum 1μF ceramic bypass capacitor
between VEE and INN.
●● Place the BST capacitor close to the pins BST and LX.
●● Place an unbroken ground plane on the layer closest
to the surface layer with the inductor, device, and the
input and output capacitors.
●● The surface area of the LX and BST nodes should be
as small as possible to minimize emissions.
●● The exposed pad on the bottom of the package must
be soldered to AGND of the IC so that the pad is
connected to ground electrically and also acts as a
heat sink thermally. To keep thermal resistance low,
extend the ground plane as much as possible, and
add thermal vias under and near the device to additional ground planes within the circuit board.
●● Run the current-sense lines FB and the line from the
bottom side of the current-sense resistor very close
to each other. The Kelvin line from the bottom of the
current-sense resistor when doing external current
sensing should go directly to the AGND pin of the IC.
Do not cross these critical signal lines with switching
power lines.
●● Use separate ground planes on different layers of the
PCB for AGND and PGND. All the components connected to the pins REFI, COMP, OUT, and PWMFRQ
go to the AGND plane. Connect both of these planes
together at a single point where the switching activity
is minimum.
●● When using the PWMDIM pin for performing PWM
dimming with a DC voltage generated using a resistive divder from the VEE supply, ensure that the bottom resistor of the resistive divider is connected to
the INN plane where it is quiet.
●● Use 2oz or thicker copper to keep trace inductances
and resistances to a minimum. Thicker copper conducts heat more effectively, thereby reducing thermal
impedance. Thin copper PCBs compromise efficiency
in applications involving high currents.
Maxim Integrated │ 19
MAX25610A/MAX25610B
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
Typical Application Circuits
Buck LED Driver
VIN+
CIN
BATTERY
GND
DOMAIN
INP
BST
INN
VINCVEE
PWM OR
ANALOG
DIMMING
LX
LX
VEE
OUT
CBST
L
LED1
ROUT1
PWMDIM
MAX25610A
OPEN-DRAIN
FAULT
CPWMFRQ
ROUT2
PGND
VCC
RPWMFRQ
RREFI
LEDn
FLT
PWMFRQ
CVCC
COUT
FB
VCC
COMP
VIN-
100kΩ
CCOMP
REFI
AGND
RCOMP
IC-GND
DOMAIN
Buck LED Driver with Accurate Current Regulation
VIN+
CIN
BATTERY
GND
DOMAIN
VIN-
INP
INN
CVEE
PWM OR
ANALOG
DIMMING
BST
LX
LX
VEE
OUT
CBST
L
LED1
ROUT1
PWMDIM
MAX25610A
MAX25610B
OPEN-DRAIN
FAULT
CPWMFRQ
ROUT2
COUT
LEDn
FLT
PGND
PWMFRQ
RPWMFRQ
CVCC
RREFI1
RREFI2
www.maximintegrated.com
RCS_LED
FB
VCC
COMP
CCOMP
REFI
AGND
RCOMP
VINIC-GND
DOMAIN
Maxim Integrated │ 20
MAX25610A/MAX25610B
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
Typical Application Circuits (continued)
Buck DC-DC Converter
VIN+
CIN
INP
VIN-
BST
INN
LX
LX
CVEE
VEE
OUT
CBST
L
ROUT1
PWMDIM
MAX25610A
MAX25610B
OPEN-DRAIN
FAULT
CPWMFRQ
ROUT2
COUT
FLT
RFB1
PGND
PWMFRQ
RPWMFRQ
FB
VCC
CVCC
RREFI1
COMP
RFB2
CCOMP
VIN-
REFI
RREFI2
AGND
RCOMP
IC-GND
DOMAIN
Buck Boost LED Driver
VIN+
CIN
CIN2
INP
IC-GND VINBATTERY
GND
DOMAIN
PWM OR
ANALOG
DIMMING
CVEE
INN
BST
LX
LX
VEE
OUT
BATTERY
GND
VIN-
L
LED1
ROUT1
PWMDIM
MAX25610A
OPEN-DRAIN
FAULT
ROUT2
FLT
PWMFRQ
RPWMFRQ
CVCC
RREFI
COUT
LEDn
PGND
CPWMFRQ
FB
VCC
COMP
VCC
100kΩ
CCOMP
REFI
AGND
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CBST
RCOMP
IC-GND
DOMAIN
Maxim Integrated │ 21
MAX25610A/MAX25610B
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
Typical Application Circuits (continued)
Buck Boost Regulator with Accurate Regulation
VIN+
CIN
CIN2
IC-GND
VIN-
BATTERY
GND
DOMAIN
CVEE
PWM OR
ANALOG
DIMMING
INP
INN
BST
LX
LX
VEE
OUT
BATTERY
GND
CBST
L
VIN-
LED1
ROUT1
PWMDIM
MAX25610A
OPEN-DRAIN
FAULT
ROUT2
FLT
COUT
LEDn
PGND
CPWMFRQ
PWMFRQ
RCS_LED
RPWMFRQ
FB
VCC
CVCC
RREFI1
RREFI2
COMP
CCOMP
REFI
AGND
RCOMP
IC-GND
DOMAIN
Boost LED Driver
VIN+
CIN
CIN2
BATTERY
GND
DOMAIN
IC-GND
VIN-
PWM OR
ANALOG
DIMMING
INP
INN
CVEE
BST
LX
LX
VEE
OUT
CBST
L
BATTERY
GND
VIN-
ROUT1
PWMDIM
MAX25610A
OPEN-DRAIN
FAULT
ROUT2
FLT
COUT
PWMFRQ
RPWMFRQ
RCS_LED
FB
VCC
CVCC
RREFI1
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LEDn
PGND
CPWMFRQ
RREFI2
LED1
COMP
CCOMP
REFI
AGND
RCOMP
IC-GND
DOMAIN
Maxim Integrated │ 22
MAX25610A/MAX25610B
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
Ordering Information
PART
TEMP RANGE
FREQUENCY
PIN-PACKAGE
MAX25610AAUE/V+
-40°C to +125°C
400kHz
16 TSSOP
MAX25610BAUE/V+
-40°C to +125°C
2.2MHz
16 TSSOP
MAX25610AATE/VY+
-40°C to +125°C
400kHz
16 TQFN
MAX25610BATE/VY+
-40°C to +125°C
2.2MHz
16 TQFN
MAX25610AAUE+
-40°C to +125°C
400kHz
16 TSSOP
MAX25610BAUE+
-40°C to +125°C
2.2MHz
16 TSSOP
MAX25610AATEY+
-40°C to +125°C
400kHz
16 TQFN
MAX25610BATEY+
-40°C to +125°C
2.2MHz
16 TQFN
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
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Maxim Integrated │ 23
MAX25610A/MAX25610B
Synchronous Buck and Buck-Boost
LED Driver/DC-DC Converter
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
0
12/18
Initial release
1
12/18
Updated Electrical Characteristics, Ordering Information, and equation
2
2/19
Updated PWMFRQ equation in Pin Description, removed future-product status
from MAX25610BAUE/V+, MAX25610AATE/VY+, and MAX25610BATE/VY+,
added MAX25610AAUE+*, MAX25610BAUE+*, MAX25610AATEY+*, and
MAX25610BATEY+* in Ordering Information
3
3/19
Added future-product status to MAX25610BAUE/V+* and MAX25610BATE/VY+* in
Ordering Information
23
4
3/19
Delete the future-product status to MAX25610BAUE/V+ and MAX25610BATE/VY+ in
Ordering Information
23
5
4/19
Remove future-product status from non/V parts in Ordering Information
23
DESCRIPTION
—
4, 14, 23
9, 23
For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
© 2019 Maxim Integrated Products, Inc. │ 24
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