Rainbow Electronics MAX16831 User Manual

General Description

The MAX16831 is a current-mode, high-brightness LED
(HBLED) driver designed to control two external
n-channel MOSFETs for the single-string LED current
regulation. The MAX16831 integrates all the building
blocks necessary to implement fixed-frequency HBLED
drivers with wide-range dimming control. The
MAX16831 is configurable to operate as a step-down
(buck), step-up (boost), or step-up/-down (buck-boost)
current regulator.

Current-mode control with leading-edge blanking simpli­fies control-loop design. Internal slope compensation
stabilizes the current loop when operating at duty cycles
above 50%. The MAX16831 operates over a wide input
voltage range and is capable of withstanding automo­tive load-dump events. Multiple MAX16831s can be
synchronized to each other or to an external clock. The
MAX16831 includes a floating dimming driver for
brightness control with an external n-channel MOSFET
in series with the LED string.

HBLED drivers using the MAX16831 achieve efficien­cies of over 90% in automotive applications. The
MAX16831 also includes a 1.4A source and 2.5A sink
gate driver for driving switching MOSFETs in high-power
LED driver applications, such as front light assemblies.
The dimming control allows for wide PWM dimming at
frequencies up to 2kHz. Higher dimming ratios of up to
1000:1 are achievable at lower dimming frequencies.

The MAX16831 is available in a 32-pin thin QFN package
with exposed pad and operates over the -40°C to
+125°C automotive temperature range.

Applications

Automotive Exterior Lighting:

High-Beam/Low-Beam/Signal Lights
Rear Combination Lights (RCL)
Daytime Running Lights (DRL)
Fog Light and Adaptive Front Light Assemblies

Industrial and Architectural Lighting

Emergency Lighting

Projectors with RGB LED Light Sources

Navigation and Marine Indicators

Features

o Wide Input Range: 6V to 76V With Cold-Start

Operation to 5.5V

o Integrated Differential LED Current-Sense

Amplifier

o Floating Dimming Driver Capable of Driving an

n-Channel MOSFET

o 5% LED Current Accuracy

o 200Hz On-Board Ramp Syncs to External PWM

Dimming Signal

o Programmable Switching Frequency (125kHz to

600kHz) and Synchronization

o Output Overvoltage Load Dump, LED Short,

Overtemperature Protection

o Low 107mV LED Current Sense for High

Efficiency

o Enable/Shutdown Input with Shutdown Current

Below 45µA

MAX16831

High-Voltage, High-Power LED Driver with

Analog and PWM Dimming Control

________________________________________________________________

Maxim Integrated Products

1

19-0809; Rev 0; 4/07

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Ordering Information

+

Denotes lead-free package.

*

EP = Exposed pad.

V

IN

DIM

R

CS

C

F

R

T

C

REG1

R

UV2

DRV

DRI

REG1

DIM

CS

V

CC

SNS+

FB

QGND

RTSYNC

CS-

CS+

LO

COMP

REG2

DGT

HI

OV

UVEN

SNS-

AGND

R

SENSE

R2

C2

R

OV1

R

OV2

CLMP

SGND

C

CLMP

C

REG2

R1

C1

R

D

LEDs

BUCK-BOOST CONFIGURATION

R

UV1

C

UVEN

Q

S

MAX16831

Typical Operating Circuits

Pin Configuration appears at end of data sheet.

Typical Operating Circuits continued at end of data sheet.

PART TEMP RANGE

PIN­PACKAGE

MAX16831ATJ+ -40°C to +125°C 32 TQFN-EP* T3255M-4

PKG

CODE

MAX16831

High-Voltage, High-Power LED Driver with
Analog and PWM Dimming Control

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= V

UVEN

= 14V, C

REG1

= 1µF, C

REG2

= 1µF, C

CLMP

= 0.1µF, RT= 25kΩ, TA= TJ = -40°C to +125°C, unless otherwise noted.

Typical specifications are at T

A

= +25°C.)

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.

VCC, HI, LO, CLMP to QGND.................................-0.3V to +80V

CS+, CS-, DGT, UVEN to QGND............................-0.3V to +80V

UVEN to QGND ..........................................-0.3V to (V

CC

+ 0.3V)

DRV to SGND .........................................................-0.3V to +18V

DRI, REG2, DIM to AGND ......................................-0.3V to +18V

QGND, SGND to AGND ........................................-0.3V to +0.3V

SNS+ to SNS- ...........................................................-0.3V to +6V

CS, FB, COMP, SNS+, SNS-, OV, REF,

RTSYNC to AGND .................................................-0.3V to +6V

REG1, CLKOUT to AGND ........................................-0.3V to +6V

CS+ to CS- .............................................................-0.3V to +12V

HI to LO ..................................................................-0.3V to +36V

CS+, CS-, DGT, CLMP to LO .................................-0.3V to +12V

CS+, CS-, DGT, CLMP to LO ........................-0.3V to (HI + 0.3V)

HI to CLMP .............................................................-0.3V to +28V

Continuous Power Dissipation* (T

A

= +70°C)

32-Pin TQFN (derate 34.5mW/°C above +70°C) ........2758mW

Thermal Resistance*

θ

JA

.................................................................................29°C/W

θ

JC

................................................................................1.7°C/W

Operating Temperature Range .........................-40°C to +125°C

Maximum Junction Temperature .....................................+150°C

Storage Temperature Range .............................-60°C to +150°C

Reflow Temperature.........................................................+240°C

Lead Temperature (soldering, 10s) .................................+300°C

*As per JEDEC 51 standard, multilayer board (PCB).

Input Voltage Range V

Supply Current I

Shutdown Current I

UVEN

VCC UVLO Threshold

VCC Threshold Hysteresis V

UVEN Threshold

UVEN Input Current I

REGULATORS

REG1 Regulator Output V

REG1 Dropout Voltage I

REG1 Load Regulation ∆V/∆IVCC = 7.5V, 0 ≤ I

REG2 Regulator Output V

REG2 Dropout Voltage I

REG2 Load Regulation ∆V/∆IVCC = 7.5V, 0 ≤ I

HIGH-SIDE REGULATOR (CLMP) (All Voltages Referred to LO) (Note 2)

CLMP UVLO Threshold V

CLMP UVLO Threshold
Hysteresis

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

CC

I

Q

SHDN

V

CC_R

V

CC_F

CC_HYS

V

UVR

V

UVF

UVEN

REG1

REG2

CLMPTHVCLMP

V

CLMPHYS

V

VCC rising 5.5 6.0

VCC falling 5.0 5.5

V

V

V

0 ≤ I

I

7.5V ≤ VCC ≤ 76V, I

VCC = 5.7V, 0 ≤ I

= 0A 2.7 4.5 mA

REG2

≤ 0.8V 25 45 µA

UVEN

rising 1.100 1.244 1.360

UVEN

falling 1.000 1.145 1.260

UVEN

= 0V and V

UVEN

≤ 2mA, 7.5V ≤ VCC ≤ 76V 4.75 5.00 5.25

REG1

= 2mA, VCC = 5.7V 4.00 4.50 5.25

REG1

= 2mA (Note 1) 0.5 1.0 V

REG1

= 20mA (Note 1) 0.5 V

REG2

rising 2.0 2.5 3.0 V

5.5 76.0 V

0.4 V

= 76V, VCC = 77V -0.2 +0.2 µA

UVEN

≤ 2mA 25 Ω

REG1

= 1mA 6.65 7.00 7.35

REG2

≤ 20mA 4.5 5.0

REG2

≤ 20mA 25 Ω

REG2

0.22 V

V

V

V

V

MAX16831

High-Voltage, High-Power LED Driver with

Analog and PWM Dimming Control

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC= V

UVEN

= 14V, C

REG1

= 1µF, C

REG2

= 1µF, C

CLMP

= 0.1µF, RT= 25kΩ, TA= TJ = -40°C to +125°C, unless otherwise noted.

Typical specifications are at T

A

= +25°C.)

CLMP Regulator Output Voltage V

CURRENT-SENSE AMPLIFIER (CSA)

Differential Input Voltage Range

Common-Mode Range 0V

CS+ Input Bias Current I

CS- Input Bias Current I

Unity-Gain Bandwidth From (CS+ - CS-) to CS 1.0 MHz

REF OUTPUT BUFFER

REF Output Voltage V

DIM DRIVER

Source Current

Sink Current

GATE DRIVER

DRI UVLO Threshold V

DRI UVLO Threshold Hysteresis V

Driver Output Impedance

Peak Sink Current I

Peak Source Current I

PWM, ILIM, AND HICCUP COMPARATOR

PWM Comparator Offset Voltage V

Peak Current-Limit Comparator
Trip Threshold

Peak Current-Limit Comparator
Propagation Delay (Excluding
Blanking Time)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

CLMP

V

-

CS+

V

CS-

CS+

CS-

REF

UVLO_TH

UVLO_HYST

Z

OUT_LVDRI

Z

OUT_HVDRI

SK

SR

8.7V ≤ (V

5.0V ≤ (VHI - VLO) ≤ 8.7V, I

- VLO) ≤ 36V, I

HI

= 1mA 5.5 8.0 10.0

CLMP

(V

- VLO)

CLMP

= 250µA

HI

- 0.7

0 0.3 V

CC

V

- V

CS+

V

CS+

-100µA ≤ I

V

CLMP

V

CLMP

V

CLMP

V

CLMP

= 0.3V -250 +250 µA

CS-

- V

= 0.3V 400 µA

CS-

≤ +100µA 2.85 3.00 3.15 V

REF

- VLO = 4V 5 20

- VLO = 8V 30 67

- VLO = 4V 10 22

- VLO = 8V 40 76

DRI rising 4.0 4.2 4.4 V

0.3 V

= 7.0V, DRV sinking 250mA 2.8 4

= 7.0V, DRV sourcing 250mA 5.0 8

V

= 7.0V 2.5 A

DRI

V

= 7.0V 1.4 A

DRI

COMP

- (V

SNS+

- V

SNS-)

0.7 V

160 200 240 mV

50mV overdrive 40 ns

V

V

mA

mA

Ω

HICCUP Comparator Trip
Threshold

SNS+ Input Bias Current V

SNS- Input Bias Current V

Blanking Time t

BLNK

SNS+

SNS+

= 0V, V

= 0V, V

235 300 385 mV

= 0V -100 -65 µA

SNS-

= 0V -100 -65 µA

SNS-

40 ns

MAX16831

High-Voltage, High-Power LED Driver with
Analog and PWM Dimming Control

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(VCC= V

UVEN

= 14V, C

REG1

= 1µF, C

REG2

= 1µF, C

CLMP

= 0.1µF, RT= 25kΩ, TA= TJ = -40°C to +125°C, unless otherwise noted.

Typical specifications are at T

A

= +25°C.)

ERROR AMPLIFIER

FB Input Bias Current -100 +100 nA

EAMP Output Sink Current VFB = 1.735V, V

EAMP Output Source Current VFB = 0.735V, V

EAMP Input Common-Mode
Voltage

EAMP Output Clamp Voltage 1.1 1.7 2.4 V

Voltage Gain A

Unity-Gain Bandwidth GBW

OSCILLATOR, OSC SYNC, CLK, AND CLKOUT

RTSYNC Frequency Range

RTSYNC Oscillator Frequency

RTSYNC High-Level Voltage V

RTSYNC Low-Level Voltage V

CLKOUT High Level I

CLKOUT Low Level I

CLKOUT Maximum Load
Capacitance

DIM SYNC, DIM RAMP, AND DIM PWM GEN

Internal Ramp Frequency f

External Sync Frequency Range f

External Sync Low-Level Voltage V

External Sync High-Level Voltage V

DIM Comparator Offset V

DIGITAL SOFT-START

Soft-Start Duration t

OVERVOLTAGE COMPARATOR, LOAD OVERCURRENT COMPARATOR

OVP Overvoltage Comparator
Threshold

OVP Overvoltage Comparator
Hysteresis

SLOPE COMPENSATION

Slope Compensation Peak
Voltage Per Cycle

Slope Compensation External clock applied to RTSYNC 15 mV/µs

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

V

f

SWMIN

f

SWMAX

SIHL

SILL

C

CLK_CAPfSW

RAMP

DIM

LTH

HTH

DIMOS

SS

V

OV

V

OV_HYST

= 1V 3 7 mA

COMP

= 1V 2 7 mA

COMP

0 3.0 V

R

= 100kΩ to AGND 80 dB

COMP

R

= 100kΩ to AGND, C

COMP

to AGND

RT = 25kΩ 475 500 525

R

= 100kΩ 106 125 143

T

= 0.8mA 2.8 V

SINK

= 1.6mA 0.4 V

SOURCE

= 500kHz 500 pF

VOV rising 1.20 1.235 1.27 V

Clock generated by R

T

COMP

= 100pF

0.5 MHz

125

500

2.8 V

0.4 V

160 200 240 Hz

80 2000 Hz

0.4 V

3.2 V

170 200 300 mV

4.0 ms

63.5 mV

120 mV

kHz

kHz

MAX16831

High-Voltage, High-Power LED Driver with

Analog and PWM Dimming Control

_______________________________________________________________________________________ 5

ELECTRICAL CHARACTERISTICS (continued)

(VCC= V

UVEN

= 14V, C

REG1

= 1µF, C

REG2

= 1µF, C

CLMP

= 0.1µF, RT= 25kΩ, TA= TJ = -40°C to +125°C, unless otherwise noted.

Typical specifications are at T

A

= +25°C.)

Note 1: Dropout voltage is defined as the input to output differential voltage at which the regulator output voltage drops 100mV below

the nominal output voltage.

Note 2: V

CLMPTH

determines the voltage required to operate the current-sense amplifier. The DIM driver requires 2.5V for (V

CLMP

- VLO)

to drive the external MOSFET. V

HI

is typically one diode drop above V

CLMP

. A large capacitor connected to V

CLMP

slows the
response of the LED current-sense circuitry, resulting in current overshoot. To ensure proper operation, connect a 0.1µF
capacitor from CLMP to LO.

Typical Operating Characteristics

(VCC= V

UVEN

= 14V, C

REG1

= 1µF, C

REG2

= 10µF, C

CLMP

= 0.1µF, RT= 25kΩ, RCS= 0.1Ω, TA= +25°C, unless otherwise noted.)

18

20

19

22

21

24

23

25

27

26

28

-60 -20 0 20-40 40 60 80 120100 140

SHUTDOWN CURRENT

vs. TEMPERATURE

MAX16831 toc01

TEMPERATURE (°C)

SHUTDOWN CURRENT (µA)

2.0

2.2

2.1

2.4

2.3

2.6

2.5

2.7

2.9

2.8

3.0

-60 -20 0 20-40 40 60 80 120100 140

OPERATING CURRENT

vs. TEMPERATURE

MAX16831 toc02

TEMPERATURE (°C)

OPERATING CURRENT (mA)

DGT AND DRV NOT
SWITCHING

40
30
20
10

0

70
60
50

80

90

110
100

120

0 10203040

VOLTAGE ACROSS LED CURRENT-SENSE

RESISTOR vs. SUPPLY VOLTAGE

MAX16831 toc03

SUPPLY VOLTAGE (V)

VOLTAGE ACROSS R

CS

(mV)

THERMAL SHUTDOWN

Thermal Shutdown Temperature T

Hysteresis ∆T

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

SHDN

SHDN

Temperature rising +165 °C

20 °C

MAX16831

High-Voltage, High-Power LED Driver with
Analog and PWM Dimming Control

6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VCC= V

UVEN

= 14V, C

REG1

= 1µF, C

REG2

= 10µF, C

CLMP

= 0.1µF, RT= 25kΩ, RCS= 0.1Ω, TA= +25°C, unless otherwise noted.)

6.80

6.95

6.90

6.85

7.00

7.05

7.10

-60 200-40 -20 40 60 80 100 120 140

REG2 OUTPUT VOLTAGE

vs. TEMPERATURE

MAX16831 toc04

TEMPERATURE (°C)

REG2 OUTPUT VOLTAGE (V)

I

REG2

= 20mA

0

2

1

4

3

5

6

7

8

010155 2025303540

REG2 OUTPUT VOLTAGE

vs. SUPPLY VOLTAGE

MAX16831 toc05

SUPPLY VOLTAGE (V)

REG2 OUTPUT VOLTAGE (V)

I

REG2

= 20mA

4.90

4.96

4.94

4.92

4.98

5.00

5.02

-60 200-40 -20 40 60 80 100 120 140

REG1 OUTPUT VOLTAGE

vs. TEMPERATURE

MAX16831 toc06

TEMPERATURE (°C)

REG1 OUTPUT VOLTAGE (V)

I

REG1

= 2mA

0

1

2

3

4

5

6

0105 152025303540

REG1 OUTPUT VOLTAGE

vs. SUPPLY VOLTAGE

MAX16831 toc07

SUPPLY VOLTAGE (V)

REG1 OUTPUT VOLTAGE (V)

I

REG1

= 2mA

7.5

7.7

7.6

7.8

8.1

8.2

8.0

7.9

8.3

-60 -20 0 20 40-40 60 80 100 120 140

CLMP REGULATOR VOLTAGE

vs. TEMPERATURE

MAX16831 toc08

TEMPERATURE (°C)

CLMP VOLTAGE (V)

VHI - VLO = 11V
CLMP VOLTAGE = V

CLMP

- VLO

1

3

2

5

4

6

7

8

9

010155 2025303540

CLMP REGULATOR VOLTAGE

vs. (V

HI

- VLO)

MAX16831 toc09

VHI - VLO (V)

CLMP REGULATOR VOLTAGE (V)

CLMP REGULATOR VOLTAGE = V

CLMP

- V

LO

2.96

2.99

2.98

2.97

3.00

3.01

3.02

-60 200-40 -20 40 60 80 100 120 140

REF OUTPUT VOLTAGE

vs. TEMPERATURE

MAX16831 toc10

TEMPERATURE (°C)

REF OUTPUT VOLTAGE (V)

I

REF

= 100µA

2.96

2.97

2.99

2.98

3.01

3.00

3.02

-225 -125 -75-175 -25 25 75 125 175 225

REF OUTPUT VOLTAGE

vs. LOAD CURRENT

MAX16831 toc11

LOAD CURRENT (µA)

REF OUTPUT VOLTAGE (V)

470

500

490

480

510

520

530

-60 200-40 -20 40 60 80 100 120 140

PWM OSCILLATOR FREQUENCY

vs. TEMPERATURE

MAX16831 toc12

TEMPERATURE (°C)

PWM FREQUENCY (kHz)

RT = 25kΩ