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General Description

The MAX8790A evaluation kit (EV kit) is a fully assem-

bled and tested surface-mount PCB that evaluates the

high-efficiency MAX8790A white LED (WLED) driver.

The MAX8790A EV kit utilizes a step-up DC-DC con-

verter to generate the voltage required to drive up to six

strings of eight surface-mount WLEDs. The EV kit is

supply mode) and can be configured to provide a fixed

20mA or adjustable 15mA to 25mA full-scale LED cur-

rent. In addition, the MAX8790A provides LED current

control through either analog or digitally adjusted

pulse-width modulation (DPWM) dimming modes. As

shipped, the MAX8790A EV kit is configured for evalua-

tion with two strings of eight WLEDs.

Features

♦ 7V to 21V Input Range

♦ 86% Efficiency (VIN = 12V, Load = Two WLED

Strings)

♦ WLED Drives Up to 25mA/String

♦ Drives Two Strings of Eight WLEDs (Capable of

Driving Up to Six Strings)

♦ Analog or Direct DPWM Dimming Control

♦ 100:1 Dimming Range

♦ 750kHz PWM Switching Frequency (Selectable:

1MHz or 500kHz, Component Change Required)

♦ Fully Assembled and Tested

Evaluates: MAX8790A

MAX8790A Evaluation Kit

________________________________________________________________

Maxim Integrated Products

19-0766; Rev 1; 3/08

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.

PART TYPE

MAX8790AEVKIT+ EV Kit

DESIGNATION QTY DESCRIPTION

C1, C3, C4 3

0.1µF ±10%, 50V X7R ceramic

capacitors (0603)

Murata GRM188R71H104K

TDK C1608X7R1H104K

C2 1

1µF ±10%, 6.3V X5R ceramic

capacitor (0603)

Murata GRM188R60J105K

TDK C1608X5R1A105K

C5 1

2.2µF ±10%, 50V X7R ceramic

capacitor (1206)

Murata GRM31CR71H225K

KEMET C1206C225K5RAC

C6, C8,

C11–C16

Not installed, ceramic capacitors

(1206)

C7 1

10µF ±10%, 25V X5R ceramic

capacitor (1206)

Murata GRM31CR61E106KA

TDK C3216X5R1E106K

C9, C10, C17 0

Not installed, ceramic capacitors

(0603)

DESIGNATION QTY DESCRIPTION

D1 1

2A, 40V Schottky diode (M-Flat)

Toshiba CMS11 (TE12L, Q)

Nihon EC21QS04

D2–D17 16

White LEDs

Nichia NSSW008C

OPTEK OVSRWACR6

D18–D49 0 Not installed, white LEDs

JU1, JU3,

JU6, JU7

4 3-pin headers

JU2, JU4,

JU5, JU12

4 2-pin headers

JU8–JU11,

JU13

0 Not installed, 3-pin headers

L1 1

4.7µH, 2.15A, 64.1mΩ power inductor

TDK LTF5022T-4R7N2R0

Sumida CDRH5D16-4R7 (1.8mm)

N1 1

60V, 2.8A n-channel MOSFET

(6 TSOP)

SANYO Semiconductor CPH6424

(Top Mark: ZA)

Fairchild Semiconductor FDC5612

(Top Mark: 562)

Summary of content (11 pages)

PAGE 1
9-0766; Rev 1; 3/08 MAX8790A Evaluation Kit The MAX8790A evaluation kit (EV kit) is a fully assembled and tested surface-mount PCB that evaluates the high-efficiency MAX8790A white LED (WLED) driver. The MAX8790A EV kit utilizes a step-up DC-DC converter to generate the voltage required to drive up to six strings of eight surface-mount WLEDs.
PAGE 2
Evaluates: MAX8790A MAX8790A Evaluation Kit Component List (continued) DESIGNATION QTY DESCRIPTION R1 1 51kΩ ±5% resistor (0603) R2 1 R3 1 R4 1 37.4kΩ ±1% resistor (0603) R5 1 R6 1 R7 DESIGNATION QTY 1 1.2kΩ ±5% resistor (0603) 100kΩ potentiometer, multiturn R9, R10 2 100kΩ ±5% resistors (0603) 511kΩ ±1% resistor (0603) R11–R16 0 Not installed, resistors (0603) 1MΩ ±1% resistor (0603) U1 1 56mΩ ±1%, 0.
PAGE 3
MAX8790A Evaluation Kit LED current control is accomplished through either analog or digital dimming modes, which achieve a 100:1 dimming range. Both dimming modes utilize the pulse-width modulation (PWM) signal supplied at the BRT input pad to control the LED current sources. See the LED Dimming Mode section for more details. As configured, the MAX8790A EV kit operates with a 750kHz switching frequency and an output voltage of 35V.
PAGE 4
Evaluates: MAX8790A MAX8790A Evaluation Kit Table 4. Jumper JU4 Function SHUNT POSITION ISET PIN ILED(FS) Installed Connected to VCC 20mA Not installed* Connected to GND through R1 and R2 Adjustable from 15mA to 25mA *Default position. LED Dimming Mode The MAX8790A provides a 100:1 dimming range through analog or digital control methods. In both methods, the BRT input signal is translated into a control signal for each of the six current sources.
PAGE 5
MAX8790A Evaluation Kit Table 7. Jumper JU12 Function SHUNT POSITION FB_ PIN STRING_ SHUNT POSITION VOUT 1-2 Connected to cathode of WLED string Enabled Installed* Connected to anodes of on-board WLED strings 2-3 Connected to GND Disabled Not installed Connect to anodes of off-board WLED strings Not installed Connect to an external WLED string On-board WLED string not used Off-Board White LED String Configuration The MAX8790A EV kit is also used to drive off-board WLED strings.
PAGE 6
GND BRT SHDN GND VIN VCC R10 100kΩ VCC JU2 R9 100kΩ VCC 4.5V TO 5.5V PGND VIN 7V TO 21V JU1 JU5 R1 51kΩ 3 R3 511kΩ 1% R2 100kΩ JU4 C3 0.1μF VCC C7 10μF 25V C17 OPEN 3 C4 0.1μF C10 OPEN C9 OPEN JU3 1 2 VCC R8 1.2kΩ C2 1μF C1 0.
PAGE 7
MAX8790A Evaluation Kit Evaluates: MAX8790A Figure 2.
PAGE 8
Evaluates: MAX8790A MAX8790A Evaluation Kit Figure 3.
PAGE 9
MAX8790A Evaluation Kit Evaluates: MAX8790A Figure 4.
PAGE 10
Evaluates: MAX8790A MAX8790A Evaluation Kit Figure 5.
PAGE 11
MAX8790A Evaluation Kit REVISION NUMBER REVISION DATE 0 3/07 Initial release 1 3/08 IC changed from MAX8790 to MAX8790A. DESCRIPTION PAGES CHANGED — All pages 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.