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19-3536; Rev 0; 12/04
MAX1576 Evaluation Kit
General Description
The MAX1576 evaluation kit (EV kit) is a fully assembled and tested circuit for evaluating the MAX1576 white LED 1x/1.5x/2x charge pump. This MAX1576 EV kit drives four white LEDs for backlighting and uses four flash LED drivers to drive one flash LED at a high current. In addition to the LED driver circuit, the EV kit includes one pulse-generator circuit and momentary pushbutton switches that are used for testing the single-wire serial pulse-dimming and flash feature of the MAX1576.
Features
o MAX1576 Powers Up to 4 Main LEDs and 4 Flash LEDs EV Kit Powers 4 Main LEDs and 1 Flash LED o 85% Average Efficiency (PLED/PBATT) over Li+ Battery Discharge o 0.7% Typical LED Current Matching o Adaptive 1x/1.5x/2x Mode Switchover o Single-Wire Serial Pulse Interface (5% to 100% Brightness) for Main o 2.7V to 5.5V Supply Voltage Range o 24-Pin (4mm x 4mm) Thin QFN Package o Fully Assembled and Tested
Evaluates: MAX1576
Ordering Information
PART MAX1576EVKIT TEMP RANGE 0C to +70C IC PACKAGE 24 Thin QFN
Component List
DESIGNATION C1, C5 QTY 2 DESCRIPTION 4.7F 10%, 6.3V X5R ceramic capacitors (0603) TDK C1608X5R0J475K 1F 20%, 6.3V X5R ceramic capacitors (0402) TDK C1005X5R0J105M 0.01F 10%, 6.3V X7R ceramic capacitor (0402) TDK C1005X7R1E103K 2.2F 10%, 6.3V X5R ceramic capacitor (0603) TDK C1608X5R0J225K Diodes Nichia NSCW215T Not installed, diode (Nichia NBCW011T) Lumileds LXCL-PWF1 SOD-523, CMOSH-3 Central Semiconductor DESIGNATION JU1 JU2, JU3 JU4-JU8 R1 R2, R3, R5 R4 S1, S2 U1 U2 None QTY 1 2 0 1 3 1 2 1 1 0 DESCRIPTION 3-pin header 2-pin headers Not installed, PC board short 6.98k 1% resistor (0402) 10k 5% resistors (0402) 4.12k 1% resistor (0402) Momentary pushbutton switches Panasonic EVQ-PHP03T MAX1576ETG (24-pin thin QFN) MAX6816EUS-T Shunts, 2 position
C2, C3, C4
3
C6
1
C7 D1-D4 D5 D6 D9
1 4 0 1 1
________________________________________________________________ Maxim Integrated Products
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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.
MAX1576 Evaluation Kit Evaluates: MAX1576
Component Suppliers
SUPPLIER Central Semiconductor Kamaya Lumileds Nichia Panasonic TDK COMPONENT Diode Resistors LED LED Momentary switch Capacitor PHONE 631-435-1110 260-489-1533 408-435-6111 248-352-6575 714-373-7939 847-803-6100 WEBSITE www.centralsemi.com www.kamaya.com www.lumileds.com www.nichia.com www.panasonic.com www.component.tdk.com
Note: Indicate that you are using the MAX1576 EV kit when contacting these component suppliers.
Quick Start
Recommended Equipment
* 2.7V to 5.5V power supply or battery capable of delivering 1.1A
Using External Pulse Generators for Main Display Dimming
To use an external pulse generator in place of the pulse generator included with the EV kit, connect the output of the external pulse generator to ENM1 or ENM2 for the main display dimming. The grounds of the external pulse generator should be connected to the EV kit pad labeled GND. Ensure that a shunt is on the side of jumper JU1 labeled ON. Note there is a 10k pullup resistor from ENM1 to IN on the EV kit.
Procedure
The MAX1576 EV kit is fully assembled and tested. Follow the steps below to verify board operation: 1) Verify that the shunt on JU1 is connected to ON. Verify that there are shunts on JU2 and JU3. 2) Preset the power supply to between 2.7V and 5.5V. 3) Turn off the power supply. Do not turn on the power supply until all connections are completed. 4) Connect the positive power-supply terminal to the pad on the EV kit labeled IN. 5) Connect the power-supply ground terminal to the pad on the EV kit labeled GND. 6) Turn on the power supply and verify that the main LEDs are lit. 7) Push S2 for only a short duration to verify that the flash LED lights. Holding S2 down for a long duration may damage the flash LED. See the Detailed Description for testing the dimming and shutdown features.
Using 2-Bit Logic for Main Display Dimming
To use 2-bit logic dimming in place of the pulse generator included with the EV kit, first open jumper JU4 by cutting the PC board trace at JU4. Then connect the ENM1 pad to the IN pad for logic 1 and to the GND pad for logic 0. Note there is a 10k pullup resistor from ENM2 to jumper JU1 on the EV kit. To control ENM2 logic, place a shunt on the side of jumper JU1 labeled ON for logic 1 and on the side of jumper JU1 labeled OFF for logic 0. Alternately, ENM1 and ENM2 can be driven with external logic signals. In this case, connect the external logic ground reference to the GND pad of the MAX1576 EV kit.
Flash LED
To test the flash feature, press the button labeled FLASH. This button should only be held for short durations to prevent overheating of the flash LED. To test without the pushbutton switch, remove the shunts on JU2 and JU3. Use ENF1 and ENF2 to control the flash LED operation; refer to the MAX1576 data sheet for more information. Note that there are 10k pulldown resistors connected to ENF1 and ENF2.
Detailed Description
LED Dimming of the Main Display
To test the dimming feature, press the button labeled DIM MAIN. Each of the first nine button presses dims the corresponding group of LEDs by 10%. The tenth press dims the LEDs by 5%, and the eleventh press returns the LEDs to full brightness. Refer to the MAX1576 data sheet for more information on the dimming feature.
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_______________________________________________________________________________________
MAX1576 Evaluation Kit
Adjusting the Main 100% Brightness Level
The full-brightness LED current for the main display is adjustable by changing resistor R1. Calculate the value of R1 with the following equation, where ILED_ is the current through one of the LEDs with the dimming set to 100%: R1 = 0.604 V x 233 ILED _
Changing the Number of LEDs
The EV kit comes with four LEDs installed, four for the main display and one for the flash. To use fewer LEDs, locate the small pad (labeled TP_) next to the LED to be removed and connect it to the pad on the EV kit labeled IN.
Evaluates: MAX1576
Connecting External LEDs
To connect external LEDs to the MAX1576 EV kit, cut the trace shorting JU5. Connect the anodes of all the external LEDs to the small pad labeled TP9. Connect the cathodes to the small pads next to D1-D8 (TP1-TP4 for the main LEDs, TP5-TP8 for the flash LEDs). Connect any unused pads (TP1-TP8) to IN.
Adjusting the Flash 100% Brightness Level
The full-brightness LED current for the flash is adjustable by changing resistor R4. Calculate the value of R4 with the following equation, where ILED_ is the current through one of the LEDs with the dimming set to 100%: R4 = 0.604 V x 708 ILED _
Changing the Flash LED
An LED footprint, D5, was included on the EV kit for flash LEDs that are copackaged and provide two anode and two cathode connections (Nichia NBCW011T). If this flash LED is to be used, cut the trace shorting JU8, remove D6, and mount the flash LED to the D5 footprint.
Shutdown Control
One jumper is included on the EV kit for shutting down the main LEDs. To turn off the main LEDs, place the shunt on the OFF side of jumper JU1. Note that with JU1 shunted off, power is disconnected from the pulsegenerator circuit. The MAX1576 is in low-power shutdown mode when JU1 is shunted off since flash is normally off.
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Evaluates: MAX1576
MAX1576 Evaluation Kit
Figure 1. MAX1576 EV Kit Schematic
IN ENM2 JU1 C3 1F C2N 20 IN 22 INP MAX1576 C1 4.7F IN 13 C2 1F 14 GND LED2 12 TP2 18 LED1 15 TP1 D1 C7 2.2F JU4 U1 OUT 1 C1N TP9 21 C5 4.7F JU5 1 2 3 C4 1F ENM1 GND IN C1P 24 C2P 23 R2 10k D9 D2 TP3 OUT C6 0.01F 19 PGND ENM1 LED5 ENM2 JU6 LED6 JU2 4 ENF1 LED7 5 16 R3 10k R5 10k ENF2 SETM LED8 SETF 6 17 R4 4.12k D5 NOT INSTALLED 7 JU8 JU7 TP8 9 TP6 IN 3 S2 2 LED4 3 8 GND LED3 D3 TP4 11 D4 TP5 10 D6 TP7 JU3 R1 6.98k ENF1 ENF2
4
4
VCC
2
U2
IN
MAX6816
S1
GND
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MAX1576 Evaluation Kit Evaluates: MAX1576
Figure 2. MAX1576 EV Kit Component Placement Guide-- Component Side
Figure 3. MAX1576 EV Kit PC Board Layout--Component Side
Figure 4. MAX1576 EV Kit PC Board 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 _____________________ 5 (c) 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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