19-4140; Rev 3; 2/10
KIT
ATION
EVALU
BLE
AVAILA
2MHz, High-Brightness LED Drivers with
Integrated MOSFET and High-Side Current Sense
General Description
The MAX16832A/MAX16832C step-down constant-cur-
rent high-brightness LED (HB LED) drivers provide a
cost-effective design solution for automotive
interior/exterior lighting, architectural and ambient light-
ing, LED bulbs, and other LED illumination applications.
The MAX16832A/MAX16832C operate from a +6.5V to
+65V input voltage range and can provide an output
current up to 700mA, if operated up to a temperature of
+125°C, or up to a 1A if operated up to a temperature
of +105°C. A high-side current-sense resistor adjusts
the output current, and a dedicated pulse-width modu-
lation (PWM) input enables pulsed LED dimming over a
wide range of brightness levels.
These devices are well suited for applications requiring
a wide input voltage range. The high-side current sens-
ing and an integrated current-setting circuitry minimize
the number of external components while delivering an
average output current with ±3% accuracy. A hysteretic
control method ensures excellent input supply rejection
and fast response during load transients and PWM dim-
ming. The MAX16832A allows 10% current ripple, and
the MAX16832C allows 30% current ripple. Both
devices operate up to a 2MHz switching frequency,
thus allowing the use of small-sized components.
The MAX16832A/MAX16832C offer an analog dimming
feature that reduces the output current by applying an
external DC voltage below the internal 2V threshold volt-
age from TEMP_I to GND. TEMP_I also sources 25µA to
a negative temperature coefficient (NTC) thermistor con-
nected between TEMP_I and GND, thus providing an
analog thermal-foldback feature that reduces the LED
current when the temperature of the LED string exceeds
a specified temperature point. Additional features
include thermal-shutdown protection.
The MAX16832A/MAX16832C operate over the -40°C to
+125°C automotive temperature range and are available
in a thermally enhanced 8-pin SO package.
o
High-Efficiency Solution
o
6.5V to 65V Input Voltage Range
o
Output Current Up to 1A
o
On-Board 65V, 0.45Ω Power MOSFET
o
Hysteretic Control: Up to 2MHz Switching
Frequency
o
±3% LED Current Accuracy
o
200mV Current-Sense Reference
o
Resistor-Programmable Constant LED Current
o
Integrated High-Side Current Sense
o
Thermal-Foldback Protection/Linear Dimming
o
Thermal-Shutdown Protection
o
Available in a Thermally Enhanced 8-Pin SO
Package
o
-40°C to +125°C Operating Temperature Range
Features
MAX16832A/MAX16832C
Ordering Information
PART
MAX16832AASA+
MAX16832CASA+
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
8 SO-EP*
8 SO-EP*
+Denotes
a lead(Pb)-free/RoHS-compliant package.
*EP
= Exposed pad.
Typical Application Circuit
D1
HB LEDs
V
IN
R
SENSE
L1
Applications
Architectural, Industrial, and Ambient Lighting
Automotive RCL, DRL, and Fog Lights
Heads-Up Displays
Indicator and Emergency Lighting
MR16 and MR111 LED Lights
C1
3
4
GND
PGND
2
IN
1
CS
TEMP_I
DIM
LX
LX
8
7
6
5
C2
NTC*
ON
OFF
MAX16832A
MAX16832C
Pin Configuration appears at end of data sheet.
*OPTIONAL
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
2MHz, High-Brightness LED Drivers with
Integrated MOSFET and High-Side Current Sense
MAX16832A/MAX16832C
ABSOLUTE MAXIMUM RATINGS
IN, CS, LX, DIM to GND .........................................-0.3V to +70V
TEMP_I to GND .......................................................-0.3V to +6V
PGND to GND ......................................................-0.3V to +0.3V
CS to IN .................................................................-0.3V to +0.3V
Maximum Current into Any Pin
(except IN, LX, and PGND).............................................20mA
Continuous Power Dissipation (T
A
= +70°C)
8-Pin SO (derate 23.3mW/°C above +70°C)...........1860.5mW
Junction-to-Ambient Thermal Resistance (θ
JA
) (Note 1) .....43°C/W
Operating Temperature Range
700mA (max) Output Current ........................-40°C to +125°C
1A (max) Output Current ...............................-40°C to +105°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Pin-to-Pin ESD Ratings......................................................±2.5kV
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.maxim-ic.com/thermal-tutorial.
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.
ELECTRICAL CHARACTERISTICS
(V
IN
= +24V, V
DIM
= V
IN
, T
A
= T
J
= -40°C to +125°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Input Voltage Range
Ground Current
Supply Current
UNDERVOLTAGE LOCKOUT (UVLO)
V
CS
= V
IN
- 100mV, V
IN
rising until V
LX
<
0.5V
IN
V
CS
= V
IN
- 100mV, V
IN
falling until V
LX
>
0.5V
IN
0.5
MAX16832A, V
IN
- V
CS
rising from 140mV
until V
LX
> 0.5V
IN
, V
DIM
= 5V
MAX16832C, V
IN
- V
CS
rising from 140mV
until V
LX
> 0.5V
IN
, V
DIM
= 5V
MAX16832A, V
IN
- V
CS
falling from 260mV
until V
LX
< 0.5V
IN
, V
DIM
= 5V
MAX16832C, V
IN
- V
CS
falling from 260mV
until V
LX
< 0.5V
IN
, V
DIM
= 5V
Falling edge of V
IN
- V
CS
from 140mV to
260mV to V
LX
> 0.5V
IN
Rising edge of V
CS
- V
IN
from 260mV to
140mV to V
LX
< 0.5V
IN
V
IN
- V
CS
= 200mV, V
IN
= V
CS
V
IN
= V
DIM
= 24V, V
CS
= 23.9V,
I
LX
= 700mA
V
IN
= V
DIM
= 6.0V, V
CS
= 5.9V,
I
LX
= 700mA
V
DIM
= 0V, V
LX
= 65V
6.25
6.5
V
6.0
V
SYMBOL
V
IN
No switching
V
DIM
< 0.6V, V
IN
= 12V
CONDITIONS
MIN
6.5
1.5
350
TYP
MAX
65
UNITS
V
mA
µA
Undervoltage Lockout
UVLO
Undervoltage-Lockout Hysteresis
SENSE COMPARATOR
201
218
185
166
210
230
190
170
50
50
216
mV
236
198
mV
180
ns
ns
3.5
µA
Sense Voltage Threshold High
V
SNSHI
Sense Voltage Threshold Low
V
SNSLO
Propagation Delay to Output High
Propagation Delay to Output Low
CS Input Current
INTERNAL MOSFET
t
DPDH
t
DPDL
I
CSIN
0.45
1
0.9
Ω
2
10
µA
Drain-to-Source Resistance
R
DSON
LX Leakage Current
I
LX_LEAK
2
_______________________________________________________________________________________
2MHz, High-Brightness LED Drivers with
Integrated MOSFET and High-Side Current Sense
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= +24V, V
DIM
= V
IN
, T
A
= T
J
= -40°C to +125°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
DIM INPUT
DIM Input-Voltage High
DIM Input-Voltage Low
DIM Turn-On Time
DIM Input Leakage High
DIM Input Leakage Low
THERMAL SHUTDOWN
Thermal-Shutdown Threshold
Thermal-Shutdown Threshold
Hysteresis
THERMAL FOLDBACK
Thermal-Foldback Enable
Threshold Voltage
Thermal-Foldback Slope
TEMP_I Output Bias Current
V
TFB_ON
FB
SLOPE
I
TEMP_I
V
DIM
= 5V
V
DIM
= 5V
25
1.9
2.0
0.75
26.5
28
2.12
V
1/V
µA
Temperature rising
+165
10
o
MAX16832A/MAX16832C
SYMBOL
V
IH
V
IL
t
DIM_ON
CONDITIONS
V
IN
- V
CS
= 100mV
V
CS
- V
IN
= 100mV
V
DIM
rising edge to V
LX
< 0.5V
IN
V
DIM
= V
IN
V
DIM
= 0V
MIN
2.8
TYP
MAX
UNITS
V
0.6
200
8
-3
-1.5
15
0
V
ns
µA
µA
C
C
o
Typical Operating Characteristics
(V
IN
= V
DIM
= 48V, R
SENSE
= 0.3Ω, L = 220µH (connected between IN and CS). Typical values are at T
A
= +25°C, unless otherwise
noted.)
EFFICIENCY
vs. INPUT VOLTAGE
MAX16832A toc01
DUTY CYCLE
vs. INPUT VOLTAGE
90
80
DUTY CYCLE (%)
70
60
50
40
30
20
10
1 LED
3 LEDs
15 LEDs
13 LEDs
11 LEDs
9 LEDs
7 LEDs
5 LEDs
MAX16832A toc02
FREQUENCY
vs. INPUT VOLTAGE
450
400
FREQUENCY (kHz)
350
300
250
200
150
100
50
0
16 LEDs
1 LED
3 LEDs
11 LEDs
9 LEDs
7 LEDs
5 LEDs
15 LEDs
MAX16832A toc03
100
95
EFFICIENCY (%)
90
85
80
75
70
5
15
25
9 LEDs
7 LEDs
5 LEDs
3 LEDs
11 LEDs 13 LEDs 15 LEDs
100
500
13 LEDs
1 LED
0
35
V
IN
(V)
45
55
65
5
15
25
35
V
IN
(V)
45
55
65
5
15
25
35
V
IN
(V)
45
55
65
_______________________________________________________________________________________
3
2MHz, High-Brightness LED Drivers with
Integrated MOSFET and High-Side Current Sense
MAX16832A/MAX16832C
Typical Operating Characteristics (continued)
((V
IN
= V
DIM
= 48V, R
SENSE
= 0.3Ω, L = 220µH (connected between IN and CS). Typical values are at T
A
= +25°C, unless otherwise
noted.)
NORMALIZED I
LED
CURRENT
vs. INPUT VOLTAGE
MAX16832A toc04
QUIESCENT CURRENT
vs. INPUT VOLTAGE
MAX16832A toc05
PWM DIMMING
AT 200Hz (10% DUTY CYCLE)
MAX16832A toc06
1.05
1.04
NORMALIZED I
LED
CURRENT
1.03
1.02
1.01
1.00
0.99
0.98
0.97
0.96
0.95
500
450
QUIESCENT CURRENT (μA)
400
350
300
250
200
150
100
50
0
V
DIM
= 0V
V
IN
= 48V
8 LEDs
I
LED
200mA/div
13 LEDs
11 LEDs 15 LEDs
5 LEDs 7 LEDs 9 LEDs
1 LED 3 LEDs
0
V
DIM
5V/div
0
0 5 10 15 20 25 30 35 40 45 50 55 60 65
V
IN
(V)
0 5 10 15 20 25 30 35 40 45 50 55 60 65
V
IN
(V)
1ms/div
PWM DIMMING
AT 200Hz (90% DUTY CYCLE )
MAX16822A toc07
PWM DIMMING
AT 20kHz (90% DUTY CYCLE)
MAX16832A toc08
I
LED
200mA/div
I
LED
200mA/div
0
V
DIM
5V/div
0
0
V
DIM
5V/div
V
IN
= 48V
8 LEDs
10μs/div
0
V
IN
= 48V
8 LEDs
1ms/div
LED CURRENT
vs. V
TEMP_I
800
750
700
650
600
550
500
450
400
350
300
250
200
150
100
50
0
0
0.4
0.8
1.2
1.6
2.0
2.4
2.8
V
TEMP_I
(V)
MAX16832A toc09
I
LED
vs. TEMPERATURE
0.9
0.8
0.7
I
LED
(A)
0.6
0.5
0.4
0.3
0.2
0.1
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
V
IN
= 48V
MAX16832A toc10
1.0
4
_______________________________________________________________________________________
LED CURRENT (mA)
2MHz, High-Brightness LED Drivers with
Integrated MOSFET and High-Side Current Sense
MAX16832A/MAX16832C
Typical Operating Characteristics (continued)
((V
IN
= V
DIM
= 48V, R
SENSE
= 0.3Ω, L = 220µH (connected between IN and CS). Typical values are at T
A
= +25°C, unless otherwise
noted.)
LX
RDSON
vs. TEMPERATURE
V
IN
= 65V
0.6
V
IN
= 48V
LX
RDSON
(Ω)
0.5
0.4
V
IN
= 6.5V
0.3
0.2
0.1
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
MAX16832A toc11
I
TEMP_I
vs. TEMPERATURE
29.5
29.0
28.5
I
TEMP_I
(μA)
28.0
27.5
27.0
26.5
26.0
25.5
25.0
V
IN
= 48V
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
MAX16832A toc12
0.7
30.0
Pin Description
PIN
1
2
3
4
5, 6
7
8
—
NAME
CS
IN
GND
PGND
LX
DIM
TEMP_I
EP
FUNCTION
Current-Sense Input. Connect a resistor between IN and CS to program the LED current.
Positive Supply Voltage Input. Bypass with a 1µF or higher value capacitor to GND.
Ground
Power Ground
Switching Node
Logic-Level Dimming Input. Drive DIM low to turn off the current regulator. Drive DIM high to
enable the current regulator.
Thermal Foldback Control and Linear Dimming Input. Bypass with a 0.01µF capacitor to GND if
thermal foldback or analog dimming is used. See the
Thermal Foldback
section.
Exposed Pad. Connect EP to a large-area ground plane for effective power dissipation. Do not use
as the IC ground connection.
Detailed Description
The MAX16832A/MAX16832C are step-down, constant-
current, HB LED drivers. These devices operate from a
+6.5V to +65V input voltage range. The maximum output
is 1A, if the part is used at temperatures up to T
A
=
105°C. or 700mA, if it is used up to T
A
= +125°C. A high-
side current-sense resistor sets the output current and a
dedicated PWM dimming input enables pulsed LED
dimming over a wide range of brightness levels.
A high-side current-sensing scheme and an on-board
current-setting circuitry minimize the number of exter-
nal components while delivering LED current with ±3%
accuracy, using a 1% sense resistor. See Figure 1 for
an internal block diagram.
_______________________________________________________________________________________
5
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