Maxim MAX16831 Quick Start Manual

General Description

The MAX16831 evaluation kit (EV kit) demonstrates the
MAX16831 current-mode, high-brightness LED
(HBLED) driver IC. The MAX16831 EV kit is configured
as a step-down/step-up (buck-boost) topology circuit
with peak inductor current and average LED current
control for external LEDs. The MAX16831 EV kit oper­ates from a DC supply voltage of 9V to 40V and is con­figured to deliver 1A of current. The maximum output
voltage of the LED string can be up to 28V.

The MAX16831 EV kit can be configured for analog­control PWM or digital PWM dimming operation using
either an analog linear DC voltage or a digital PWM
input signal to control the LEDs’ brightness. This EV kit
has an undervoltage lockout (UVLO) feature that dis­ables the EV kit and overvoltage protection that pro­tects the circuit under no-load conditions. The EV kit
circuit also features a clock output and features an
input for synchronizing to an external clock. The
MAX16831 EV kit is a fully assembled and tested sur­face-mount printed-circuit board (PCB).

Caution: Do not power up the MAX16831 EV kit
without connecting a load to the LED+ and LED­PCB pads.

Warning: Voltages exceeding 42V may exist on the
LED+ and LED- output pads.

Features

o 9V to 40V Wide Supply Voltage Range

o 1A Output Current

o Analog-Control PWM Dimming

o PWM Dimming Control

o Output Overvoltage Protection

o Buffered Clock Output

o Lead-Free and RoHS Compliant

o Fully Assembled and Tested

Evaluates: MAX16831

MAX16831 Evaluation Kit

________________________________________________________________

Maxim Integrated Products

1

19-1243; Rev 1; 10/08

Component List

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.

Ordering Information

+

Denotes lead-free and RoHS-compliant.

DESIGNATION QTY DESCRIPTION

C1, C3, C4,

C5, C15

C2 1

C6, C14 2

C7 1

C8 1

C9 1

C10, C11, C12 3

0.1µF ±10%, 50V X7R ceramic

5

capacitors (0603)
Murata GRM188R71H104K

1µF ±10%, 16V X7R ceramic
capacitor (0603)
Murata GRM188R71C105K

1000pF ±10%, 50V X7R ceramic
capacitors (0603)
Murata GRM188R71H102K

10µF ±10%, 16V X7R ceramic
capacitor (1206)
Murata GRM31CR71C106K

100µF ±20%, 50V electrolytic
capacitor (10.3mm x 10.3mm)
Panasonic EEVFCIH101P

10µF ±10%, 50V X7S ceramic
capacitor (1210)
Taiyo Yuden UMK325C7106KM

4.7µF ±10%, 100V X7R ceramic
capacitors (2220)
Murata GRM55DR61H106K

PART TYPE

MAX16831EVKIT+ EV Kit

DESIGNATION QTY DESCRIPTION

0.047µF ±10%, 50V X7R ceramic

C13 1

C16, C17 2

D1 1

D2 0 Not installed, diode (SOD123)

D3 1

D4 1

JU1 1 2-pin header

L1 0 Not installed, inductor

L2 1

N1 1

capacitor (0603)
TDK C1608X7R1H473K

100pF ±5%, 50V C0G ceramic
capacitors (0603)
Murata GQM1885C1H101J

300mA, 100V diode (SOD123)
Diodes Inc. 1N4148W-7-F

3A, 100V Schottky diode (PowerDI)
Diodes Inc. PDS3100

1A, 100V Schottky diode (SMA)
Diodes Inc. B1100-13-F

10µH, 9.2A inductor
Sumida CDEP147NP-100MC-95

60V, 3.2A n-channel MOS FET (6-pi n TSOP )
Vishay Si3458DV-E3

Evaluates: MAX16831

MAX16831 Evaluation Kit

2 _______________________________________________________________________________________

Quick Start

Recommended Equipment

Before beginning, the following equipment is needed:

• 9V to 40V, 4A power supply

• Two digital voltmeters

• A series-connected LED string rated at 1A (28V max)

• A current probe to measure LED current

Procedures

The MAX16831 EV kit is fully assembled and tested.
Follow the steps below to verify board operation.

Caution: Do not turn on the power supply until all
connections are completed and do not power up the
MAX16831 EV kit without connecting a load to the
LED+ and LED- PCB pads.

Warning: Voltages exceeding 42V may exist on the
LED+ and LED- output pads.

1) Verify that a shunt is installed across jumper JU1
(analog dimming control).

2) Connect the power supply’s positive terminal to the
V

IN

PCB pad on the EV kit. Connect the power sup-

ply’s ground terminal to PGND PCB pad.

3) Connect the digital voltmeters across the VINand
PGND PCB pads and the LED+ and LED­PCB pads.

4) Connect the anode of the LED string to the
LED+ pad.

5) Connect the cathode of the LED string to the
LED- pad.

Component List (continued)

Component Suppliers

Note: Indicate that you are using the MAX16831 when contacting these component suppliers.

*

EP = Exposed pad.

DESIGNATION QTY DESCRIPTION

N2 1

N3 0 Not installed, MOSFET (D-Pak)

R1 1 73.2kΩ ±1% resistor (0603)

R2 1 12.4kΩ ±1% resistor (0603)

R3 1

R4 1 100Ω ±5% resistor (0603)

R5 1 1Ω ±5% resistor (0603)

R6, R7 2

Diodes, Inc. 805-446-4800 www.diodes.com

International Rectifier 310-322-3331 www.irf.com

IRC, Inc. 361-992-7900 www.irctt.com

Murata Electronics North America, Inc. 770-436-1300 www.murata-northamerica.com

Panasonic Corp. 800-344-2112 www.panasonic.com

Sumida Corp. 847-545-6700 www.sumida.com

TDK Corp. 847-803-6100 www.component.tdk.com

Vishay 402-563-6866 www.vishay.com

SUPPLIER PHONE WEBSITE

100V, 42A n-channel MOSFET (D-Pak)
International Rectifier IRLR3110Z

0.1Ω ±1%, 500mW sense resistor
(1206)
IRC/TT LRC-LR-1206LF-01-R100-F

0.04Ω ± 1%, 2W sense r esi stor s ( 2512)
IRC/TT LRC-LR-2512LF-01-R040-F

DESIGNATION QTY DESCRIPTION

R8 0 Not installed, resistor (0805)

R9 1 280kΩ ±1% resistor (0603)

R10, R15 2 4.99kΩ ±1% resistors (0603)

R11 1 1kΩ ±1% resistor (0603)

R12 1 3.32kΩ ±1% resistor (0603)

R13 1 42.2kΩ ±1% resistor (0603)

R14 1 100kΩ potentiometer (single turn)

Current-mode HBLED driver

U1 1

— 1 Shunt (JU1)

— 1 PCB: MAX16831 Evaluation Kit+

(32 TQFN-EP*)
Maxim MAX16831ATJ+

6) Clip the current probe across the LED+ wire to mea­sure the LED current.

7) Turn on the power supply and increase the input
voltage to 9V.

8) Adjust potentiometer R14 to obtain the desired LED
current duty cycle.

9) Measure the voltage between the LED+ and LED­PCB pads.

Detailed Description

The MAX16831 evaluation kit (EV kit) demonstrates the
MAX16831 current-mode HBLED driver IC. The
MAX16831 EV kit is configured in a step-down/step-up
(buck-boost) topology with peak current control and
average current control for a string of user-supplied
external HBLEDs. The MAX16831 EV kit operates from a
DC supply voltage of 9V to 40V and requires up to 4A.
The circuit is configured to deliver 1A of current into
series LED string with a maximum 28V forward voltage.

The EV kit sets the maximum series inductor current to

8.3A using parallel resistors R6 and R7. The average

LED current is set to 1A using resistor R3. A CLKOUT
PCB pad is available to monitor the oscillator frequen­cy. A DIM PCB pad is also provided for PWM dimming
operation of the external LEDs and to monitor the ana­log DC voltage applied at the MAX16831 IC DIM pin.

Undervoltage Lockout (UVLO)

The MAX16831 EV kit’s UVLO threshold is configured to

8.3V using resistors R1 and R2. The UVEN PCB pad

can be used to disable the EV kit circuit by connecting
UVEN to AGND. To configure the circuit to a different
UVLO threshold, refer to the

Setting the UVLO

Threshold

section in the MAX16831 IC data sheet.

Peak Inductor Current-Limit Setting

The parallel combination of current-sense resistors R6
and R7 sets the EV kit’s peak inductor current limit to

8.3A. Use the following equation to calculate the total

resistance needed to reconfigure the inductor peak
current limit:

where I

PEAK

is the inductor peak current and R

TOTAL

is
the total parallel resistance placed at the R6 and R7
PCB pads.

Refer to

the ILIM and HICCUP Comparator

section in
the MAX16831 IC data sheet for additional information
on setting the peak current-limit threshold.

Setting External LED Current

Resistor R3 sets the MAX16831 EV kit average LED
current to 1A. Use the following equation to calculate
R3 when reconfiguring the LED current:

where I

LED

is the LED current.

LED Dimming Control

LED dimming can be achieved on the MAX16831 EV kit
by applying a digital PWM signal or an analog DC volt­age at the DIM PCB input pad. Jumper JU1, poten­tiometer R14, resistor R15, and capacitor C15 configure
the MAX16831 EV kit for analog-control PWM dimming
operation.

Place a shunt across jumper JU1 to set the EV kit for
analog-control PWM dimming and adjust potentiometer
R14. The analog DC voltage at the DIM PCB pad sets
the duty cycle of the LED current, which controls the
external LED brightness. The MAX16831 IC DIM pin
voltage can be monitored by placing a voltmeter across
the DIM and AGND PCB pads.

Use the following equation to calculate the voltage at
the DIM PCB pad, which is necessary to program the
LED output current duty cycle, D:

where DIM is the analog DC voltage at the MAX16831
EV kit DIM PCB pad in volts, and D is the duty cycle of
the LED output current.

When operating the MAX16831 EV kit with analog-con­trol PWM dimming, the LED dimming frequency is inter­nally set by the MAX16831 IC to 200Hz.

Remove the shunt at jumper JU1 to control LED dim­ming using a digital PWM signal at the DIM PCB pad.
Apply a digital PWM signal with a 3.2V to 15V logic-high
level in the 80Hz to 2kHz frequency range and adjust
the duty cycle to adjust the LED brightness. See Table
1 for jumper JU1 setting for LED dimming operation.

Evaluates: MAX16831

MAX16831 Evaluation Kit

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Table 1. MAX16831 LED Dimming
Operation (Jumper JU1)

R

TOTAL

=

mV

160

I

PEAK

mV

107

R

3

=

I

LED

DIM D V V≅× +(.).26 02

SHUNT POSITION EV KIT DIMMING OPERATION

Not installed PWM signal applied at DIM PCB pad

Installed Analog DC voltage adjusted using R14

Evaluates: MAX16831

CLK OUTPUT

The MAX16831 EV kit features a buffered digital clock
output, CLKOUT. The MAX16831 PWM clock frequen­cy is programmed to 300kHz by resistor R13. To syn­chronize the MAX16831 EV kit to an external clock
signal, connect a clock signal with a 2.8V to 5.5V
logic level and 125kHz to 500kHz square wave at the
RTSYNC PCB pad. Refer to the

Oscillator, Clock, and

Synchronization

section in the MAX16831 IC data
sheet for information on setting the MAX16831 IC
PWM frequency.

Output Overvoltage Protection

The maximum voltage on the LED+ PCB pad is limited
to 70.8V, with respect to GND, by a feedback network
formed by resistors R9 and R10. When the voltage at
LED+ exceeds the programmed 70.8V threshold,
PWM switching is terminated and no further energy is
transferred to the load connected between LED+ and
LED-. Refer to the

Setting the Overvoltage Threshold

section in the MAX16831 IC data sheet for setting the
overvoltage threshold.

If the EV kit is turned on with no load, the voltage at
LED+ may rise to unsafe levels. Even though the EV
kit has overvoltage protection, connect the speci­fied load before powering up the EV kit.

MAX16831 Evaluation Kit

4 _______________________________________________________________________________________

Evaluates: MAX16831

MAX16831 Evaluation Kit

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Figure 1. MAX16831 EV Kit Schematic

LED+

LED+

1

2

OPEN

DRV_N3

18

DRV

RTSYNC

13

13

8

D4

23

SNS+_IN

R7

0.04Ω

R6

0.04Ω

D1

D2

12

SGND

SGND

OV

FB

CS

COMP

I.C.

I.C.

I.C.

CLKOUT

1

D3

1%

1%

DRV_N3

OPEN

12

17

16

15

14

13

R12

3.32kΩ

12

11

10
9

VIN

C9

50V

10μF

C8

50V

100μF

L1

SHORT

L2

10μH

LED-

SNS+_IN

1 2 5 6

DGT

R4

100Ω

N1

22

QGND

C6

1000pF

21

20

SNS

U1

19

SNS+

MAX16831

AGND5REF

REG1

4

3

34

24

23

N.C.

LO

VIN

25

CS+

R3

1%

0.1Ω

LED+

REG2

C3

0.1μF

26

CS-

27

C5

0.1μF

C4

0.1μF

CLMP

28

HI

29

REG2

30

CC

V

31

I.C.

32

UVEN

N.C.

2

1

REG2

DRI

N3

4

4

N2

R5

1Ω

16V

C7

10μF

DIM

6

7

C12

4.7μF

100V

C11

4.7μF

100V

C10

4.7μF

100V

R9

1%

280kΩ

R8

OPEN

C16

100pF

R10

4.99kΩ

1%

1%

R11

C13

1kΩ

0.047μF

1%

C14

1000pF

VIN

VIN

PGND

C2

1μF

R15

C1

0.1μF

R2

R1

1%

73.2kΩ

UVEN

1%

12.4kΩ

AGND

C17

100pF

1%

4.99kΩ

3

2

AGND

C15

JU1

0.1μF

DIM

RTSYNC

R14

100kΩ

1

1%

R13

42.2kΩ

CLKOUT

AGND PGND

Evaluates: MAX16831

MAX16831 Evaluation Kit

6 _______________________________________________________________________________________

Figure 2. MAX16831 EV Kit Component Placement Guide—Components Side

Figure 3. MAX16831 EV Kit PCB Layout—Component Side

Evaluates: MAX16831

MAX16831 Evaluation Kit

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Figure 4. MAX16831 EV Kit PCB Layout—GND Layer 2

Figure 5. MAX16831 EV Kit PCB Layout—VCC Layer 3

Evaluates: MAX16831

MAX16831 Evaluation Kit

8 _______________________________________________________________________________________

Figure 6. MAX16831 EV Kit PCB Layout—Solder Side

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________

9

© 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

Evaluates: MAX16831

MAX16831 Evaluation Kit

Revision History

REVISION

NUMBER

0 11/07 Initial Release —

1 10/08 Component C9 part number change. 1

REVISION

DATE

DESCRIPTION

PAGES

CHANGED