EVALUATION KIT AVAILABLE
MAX20050–MAX20053
2A Synchronous-Buck LED Drivers
with Integrated MOSFETs
General Description
The MAX20050–MAX20053 are high-brightness LED (HB
LED) drivers for automotive exterior lighting applications.
Consisting of a fully synchronous step-down converter
with integrated MOSFETs, the devices are capable of
driving a series string of LEDs at up to 2A, with a mini-
mum number of external components. The MAX20050/
MAX20052 utilize internal loop compensation to minimize
component count, while the MAX20051/MAX20053 use
external compensation for full flexibility.
The wide 4.5V to 65V input supply range supports extreme
automotive cold crank and load-dump conditions. A low-
and high-switching frequency option (400kHz or 2.1MHz)
provides the designer with the flexibility to optimize for
solution size or efficiency, while avoiding interference
within the AM band. Spread spectrum provides further
options for the designer to reduce EMI at the system level.
The MAX20050/MAX20051 have an internal switching
frequency of 400kHz, while the MAX20052/MAX20053
have an internal switching frequency of 2.1MHz.
High-side current regulation means only a single
connection to the LED string is required; grounding of the
string can be done locally. In addition to PWM dimming,
the ICs provide analog dimming using the REFI pin. Full-
scale current regulation accuracy is ±2.5%, while the
accuracy is ±8% at 10% of full-scale over the full tempera-
ture range of -40°C to +125°C. A 5V, 10mA LDO output is
available for biasing other circuits.
Fault-protection mechanisms include output overload,
short-circuit, and device overtemperature protection. The
devices are specified for operation over the full -40°C to
+125°C temperature range and are available in thermally
enhanced 12-pin (3mm x 3mm) TDFN and 14-pin (5mm x
4.4mm) TSSOP packages with an exposed pad.
Benefits and Features
●
Fully Synchronous 2A Step-Down Converter with
Integrated 0.14Ω (typ) MOSFETs
●
Wide 4.5V to 65V Input Supply Range
●
Two Switching Frequency Options: 400kHz and
2.1MHz
●
Internal Loop Compensation (MAX20050/MAX20052)
and External Loop Compensation
(MAX20051/MAX20053) Options
●
Switching Frequency Synchronized to PWM Dimming
Signal
●
Active-Low Fault (FLT) Indicator
●
Output Short-Circuit Protection
●
High-Side Current Regulation Eliminates One
Connection to LED String
●
Spread-Spectrum Mode Alleviates EMI Problems
●
Low 200mV Full-Scale High-Side Current-Sense
Voltage
●
REFI Pin Adjusts LED Current Down to Zero
●
PWM Dimming Disconnects Both High- and Low-
Side MOSFET Drivers
●
5V, 10mA LDO Output Provides Bias to Other
Circuits
●
Ultra-Low Shutdown Current (5µA typ)
●
Output Overload, Short-Circuit, and Overtemperature
Protections
●
12-Pin (3mm x 3mm) TDFN and 14-Pin (5mm x
4.4mm) TSSOP Package Options
Applications
●
●
●
●
●
●
●
Ordering Information
appears at end of data sheet.
Daytime Running Lamps (DRLs)
Fog Lamps
Clearance Lamps (CLLs)
Corner Lamps (CLs)
Rear Lamps
Head Lamps
Commercial, Industrial, and Architectural Lighting
19-6926; Rev 12; 5/19
MAX20050–MAX20053
2A Synchronous-Buck LED Drivers
with Integrated MOSFETs
Absolute Maximum Ratings
IN to AGND............................................................-0.3V to +70V
PGND to AGND ....................................................-0.3V to +0.3V
CS+, CS-, LX to AGND ................................-0.3V to (IN + 0.3V)
BST to AGND ........................................................-0.3V to +75V
BST to LX ................................................................-0.3V to +6V
PWM,
FLT
to AGND ................................................-0.3V to +6V
V
CC
to AGND ...............................-0.3V to MIN (+6V, IN + 0.3V)
COMP, REFI to AGND.................................-0.3V to V
CC
+ 0.3V
CS+ to CS- ..........................................................-0.3V to + 0.3V
Continuous Current on LX....................................................2.1A
Continuous Current on IN for TDFN ....................................1.6A
Continuous Current on IN for TSSOP ..................................2.1A
Short-Circuit Duration on V
CC
...................................Continuous
Continuous Power Dissipation (T
A
= +70°C) (Note 1)
12-Pin TDFN-EP (derate 24.4 mW/°C
above +70°C) ........................................................1951.2mW
14-Pin TSSOP-EP (derate 25.6 mW/°C
above +70°C) ........................................................2051.3mW
Operating Temperature Range ..........................-40ºC to +125ºC
Junction Temperature ...................................................... +150ºC
Storage Temperature Range .............................-65ºC to +150ºC
Lead Temperature (soldering, 10s) ................................. +300ºC
Soldering Temperature (reflow) ....................................... +260ºC
Package Thermal Characteristics
(Note 1)
TDFN
Junction-to-Ambient Thermal Resistance (θ
JA
) ..........41°C/W
Junction-to-Case Thermal Resistance (θ
JC
) ..............8.5°C/W
TSSOP
Junction-to-Ambient Thermal Resistance (θ
JA
) ..........39°C/W
Junction-to-Case Thermal Resistance (θ
JC
) .................3°C/W
Note 1:
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.
Electrical Characteristics
PARAMETER
Input Supply Voltage
IN Undervoltage Lockout
IN Undervoltage Hysteresis
(V
IN
= 12V, V
REFI
= 1.2V, V
PWM
= V
CC
, T
A
= T
J
= -40°C to +125°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)
SYMBOL
V
IN
VIN
UVLO
VINHYSTL
PWM = 0
(no switching)
V
IN
= 12V
V
IN
= 65V
V
IN
= 12V
(MAX20050/51)
V
IN
= 12V
(MAX20052/53)
V
IN
= 65V
(MAX20050/51)
V
IN
rising inferred by VCC
UVLOR
225
5
8
5
20
10
8
20
10
mA
CONDITIONS
MIN
4.5
TYP
MAX
65
4.45
UNITS
V
V
mV
μA
Supply Current
IIN
Q
PWM = 100%
(and during regulation
switching)
V
CC
REGULATOR (V
CC
)
V
CC
Output Voltage
V
CC
Dropout Voltage
V
CC
Short-Circuit Current
V
CC
Undervoltage Lockout
REFI Input Voltage Range
REFI Zero-Current Threshold
VCC
IMAX
VCC
UVLOR
VCC
UVLHYS
REFI
RNG
REFI
ZC_VTH
CS
DIFF
< 5mV
V
CC
I
VCC
= 1mA, 5.5V < V
IN
< 65V
I
VCC
= 10mA, 6V < V
IN
< 25V
I
VCC
= 5mA, V
IN
= 4.5V
V
CC
= 0V
Rising
Hysteresis
50
4
150
0.2
0.165
0.18
4.875
5
50
80
4.2
200
5.125
100
110
4.35
250
1.20
0.195
V
mV
mA
V
mV
V
V
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Maxim Integrated
│
2
MAX20050–MAX20053
2A Synchronous-Buck LED Drivers
with Integrated MOSFETs
Electrical Characteristics (continued)
PARAMETER
REFI Clamp Voltage
Input Bias Current
Common-Mode Input Range
Differential Signal Range
CS+ Input Bias Current
CS- Input Bias Current
Current-Sense Input Offset
SYMBOL
REFI
CLMP
REFI
IIN
CSCM
IN
CS
DIFF
IB
CS+
IB
CS-
CS
OS
(V
IN
= 12V, V
REFI
= 1.2V, V
PWM
= V
CC
, T
A
= T
J
= -40°C to +125°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)
CONDITIONS
I
REFI
sink = 1μA
V
REFI
= 0 to V
CC
MIN
1.274
0
-0.2
0
V
CS+
= 60V
V
CS-
= 60V
V
CS+
- V
CS-
= 200mV
V
CS+
- V
CS-
= 0V
V
CS+
- V
CS-
= 200mV
V
CS+
- V
CS-
= 0V
-1.8
4.95
4.92
215
196
37.8
192
35
2.75
2.5
285
5
5
220
200
100
40
200
40
2.85
2.6
300
42.2
208
45
2.95
2.7
315
mV
μS
dB
+200
100
100
170
140
10
115
115
340
300
nA
μA
μA
mΩ
mΩ
ns
mV
V
40
8
100
66
-0.1
+1.8
5.05
5.07
225
204
mV
TYP
1.3
20
MAX
1.326
200
+65
200
70
15
150
110
UNITS
V
nA
V
mV
μA
μA
mV
T
J
= 25°C, CSCM
IN
3V to 60V
3V < CSCM
IN
< 60V
(CS+ - CS-) = 200mV, Non-B versions
3V < CSCM
IN
< 60V
B version
REFI = 1.4V, 3V < CSCM
IN
< 60V
REFI = 1.2V, 3V < CSCM
IN
< 60V
REFI = 0.7V, 3V < CSCM
IN
< 60V
REFI = 0.4V, 3V < CSCM
IN
< 60V
V
REFI
= 1.2V 0V < CSCM
IN
< 3V
V
REFI
= 0.4V 0V < CSCM
IN
< 3V
V
CS+
rising
V
CS+
falling
V
CS-
> OUT
VTH_LOW
Current-Sense Voltage Gain
CS
GAIN
V/V
Regulation Voltage Accuracy
CS
ACC
Regulation Voltage Accuracy
Low Range
CS Common-Mode Range
Input Selector
Cycle-by-Cycle Current Limit
Transconductance
Open-Loop DC Gain
COMP Bias Current
COMP Sink Current
COMP Source Current
High-Side DMOS RDS
ON
Low-Side DMOS RDS
ON
LX Rise Time
CS
ACC
RNG
SEL
CS
LIM
g
M
COMP
IBIAS
COMP
ISINK
COMP
ISRC
R
ON,HS
R
ON,LS
t
RISE,LS
V
CS-
< OUT
VTH_LOW
V
CS+
- V
CS-
= 200mV
PWM = 0
V
COMP
= 5V
V
COMP
= 0V
I
LX
= 200mA, V
CS+
= 3V
V
CC
= 5V, I
LX
= 200mA
CS
ACC
CS
ACC
CS
ACC
-5
+5
480
-200
85
85
600
75
720
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Maxim Integrated
│
3
MAX20050–MAX20053
2A Synchronous-Buck LED Drivers
with Integrated MOSFETs
Electrical Characteristics (continued)
PARAMETER
SYMBOL
(V
IN
= 12V, V
REFI
= 1.2V, V
PWM
= V
CC
, T
A
= T
J
= -40°C to +125°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)
CONDITIONS
MAX20050/MAX20051, frequency dither
disabled
MAX20052/MAX20053, frequency dither
disabled
MIN
360
1890
50
50
Not applicable to B version
10
Rising (during regulation)
Falling (during regulation)
Rising
Falling
V
IN
= 12V
PWM low time to enter shutdown mode
IN, PWM rising to LX delay
Rising
Hysteresis
LOF
REFI_RNG
V
REFI
rising
LOF
IN_RNG
LOF
IN_FLNG
LOF
VTH
LOF
VTH_
V
IN
rising
V
IN
falling
CS
DIFF
falling, duty = max
300
8
7.3
10
3
1.35
800
1
140
180
2
210
250
165
10
325
9
8.3
25
6
1.5
0.05
70
140
105
210
350
10
9.3
40
9
1.65
0.3
150
300
1
3
300
350
2
2
TYP
400
2100
80
80
±3
2000
5
5
2
MAX
440
kHz
2310
120
120
ns
ns
%
Hz
μs
V
mV
μA
ms
μs
°C
°C
mV
V
V
%
%
V
V
µs
µs
µs
UNITS
Switching Frequency
f
SW
Minimum On-Time
Minimum Off-Time
Spread-Spectrum Range
PWM Input Frequency
PWM-to-LX Delay
PWM Threshold
PWM Pullup Current
PWM Shutdown Timer
Startup Time
Thermal Shutdown
LED Open-Fault REFI Range
LED Open-Fault Enable
Rising Threshold
LED Open-Fault Enable
Falling Threshold
LED Open-Fault Threshold
LED Open-Fault Hysteresis
Output-Voltage Low Threshold
FAULT Output Voltage
FAULT Deglitch Timer
FAULT Mask Timer
FAULT Leakage Current
t
ON_MIN
t
OFF_MIN
SS
PWM
FR
PWM
DLY
PWM
VTHR
PWM
VTHF
PWM
RIN
PWM
SHDW
t
STUP
HYS
OUTV
TH_LOW
V
CS-
falling
FAULT
VOL
FAULT
DEG
FAULT
MASK
FAULT
LGK
I
SINK
= 1mA, V
CS+
= 1V, after FAULT
DEG
elapsed
(Note 3)
(Note 4)
V
FAULT
= 5.5V
Note 2:
100% tested at T
A
= +25°C. All limits over temperature are guaranteed by design, not production tested.
Note 3:
The time duration for which the fault condition has to remain active before asserting
FLT
pin.
Note 4:
The mask timer occurs each time PWM goes from low to high. Open LED condition cannot be detected during the
mask time period.
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Maxim Integrated
│
4
MAX20050–MAX20053
2A Synchronous-Buck LED Drivers
with Integrated MOSFETs
Typical Operating Characteristics
(V
IN
= 12V, V
REFI
= 1.2V, V
PWM
= V
CC
, T
A
= +25°C, unless otherwise noted.)
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0.0
0.5
EFFICIENCY vs.
LED CURRENT
toc01
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
EFFICIENCY vs.
LED CURRENT
toc02
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
EFFICIENCY vs.
LED CURRENT
toc03
V
IN
= 24V (MAX20053)
V
IN
= 24V (MAX20051)
V
IN
= 12V (MAX20053)
V
IN
= 12V (MAX20051)
V
IN
= 12V (MAX20053)
V
IN
= 24V (MAX20051)
V
IN
= 12V (MAX20051)
2 SERIES LEDS
1.0
LED CURRENT (A)
1.5
2.0
0
1 LED
0.0
0.5
1.0
LED CURRENT (A)
1.5
2.0
0
6 SERIES LEDs
V
IN
= 48V
MAX20051
0.0
0.5
1.0
LED CURRENT (A)
1.5
2.0
1.05
1.04
1.03
I
LED
(A)
1.02
1.01
1.00
0.99
0.98
0.97
0.96
0.95
0
10
LINE REGULATION
toc04
5.25
5.20
5.15
V
CC
(V)
5.05
5.00
4.95
4.90
4.85
4.80
4.75
5.10
V
CC
VOLTAGE REGULATION vs.
TEMPERATURE
toc05
5.25
5.20
5.15
V
CC
(V)
5.10
5.05
5.00
4.95
4.90
4.85
4.80
4.75
0
10
V
CC
LINE REGULATION
toc06
2 SERIES LEDS
I
LED
= 1A
20
V
IN
(V)
30
40
50
I
VCC
= 1mA
-50
0
50
100
150
TEMPERATURE (ºC)
V
REFI
= 0V
20
30
40
50
60
70
V
IN
(V)
5.25
5.20
5.15
V
CC
(V)
5.05
5.00
4.95
4.90
4.85
4.80
4.75
0
5.10
V
CC
LOAD REGULATION
toc07
200
180
160
120
100
80
60
40
20
0
140
MINIMUM ON-TIME
vs. TEMPERATURE
toc08
200
180
160
MINIMUM OFF-TIME (ns)
140
120
100
80
60
40
20
0
MINIMUM OFF-TIME
vs. TEMPERATURE
toc09
V
REFI
= 0V
20
40
I
VCC
(mA)
60
80
MINIMUM ON-TIME (ns)
-50
0
50
100
150
-50
0
50
100
150
TEMPERATURE (ºC)
TEMPERATURE (ºC)
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