Click here for production status of specific part numbers. Evaluates: MAX25611A/MAX25611B/ MAX25611 Evaluation Kit MAX25611C/MAX25611D General Description Quick Start The MAX25611 evaluation kit (EV kit) provides a prov- Required Equipment en design to evaluate the MAX25611A/MAX25611B/ MAX25611 EV kit MAX25611C/MAX25611D automotive high-voltage, high- 12V, 5A DC power supply brightness LED (HB LED) controller. The EV kit is set up for boost and buck-boost configurations and operates A series-connected LED string rated at least 1A from a 6V to 18V DC supply voltage. The EV kit is con- Oscilloscope with a current probe figured to deliver up to 0.88A to one string of LEDs. The Procedure total voltage of the string can vary from 3V to 36V. The anode of the LED string should be connected to the LED+ The EV kit is fully assembled and tested. Follow the steps terminal. The cathode of the LED string can be connected below to verify board operation. Caution: Do not turn on either to GND (boost mode) or IN (buck-boost mode). power supply until all connections are made. In the case of boost mode, the input voltage should not 1) Verify that all jumpers (J1, J2, and J7) are in their exceed the LED string voltage. default positions, as shown in Table 1. 2) Connect the positive terminal of the 12V supply to the Benefits and Features VIN PCB pad and the negative terminal to the nearest Configured for Boost and Buck-Boost Application GND PCB pad. Analog Dimming Control 3) Connect the LED string across the LED+ and LED- Proven PCB Layout PCB pads on the EV kit for buck-boost configura - Fully Assembled and Tested Feature tion. For boost configuration, connect the LED string across the LED+ and GND PCB pads on the EV kit. Ordering Information appears at end of data sheet. The LED string voltage should be higher than the input voltage in this configuration. 4) Clip the current probe on the wire connected to the LED string. 5) Turn on the DC power supply. 6) Verify that the LEDs turn on. 7) Verify that the oscilloscope displays approximately 0.88A. 319-100334 Rev 2 9/19Evaluates: MAX25611A/MAX25611B/ MAX25611 Evaluation Kit MAX25611C/MAX25611D Alternatively, the analog dimming can be controlled by Detailed Description removing the shunt on J2 and applying a voltage between The MAX25611 EV kit provides a proven design to 0 and 5.5V on the REFI test point on the EV kit. REFI evaluate the MAX25611A/MAX25611B/MAX25611C/ voltages above 1.3V are limited to an equivalent of 1.3V MAX25611D high-voltage HB LED driver with integrated inside the IC. high-side current sense. The EV kit is set up for boost and buck-boost configurations and operates from a 6V to Pulse-Dimming Input (PWMDIM) 18V DC supply voltage. The string-forward voltage can The EV kit demonstrates the PWM dimming feature of the vary from 3V to 36V. The EV kit is optimized for 0.8A and buck controller using either an external PWM signal, or a a series of 8 LEDs in a string. Other configurations may DC voltage at the DIM pin. require changes to component values. Analog-to-PWM dimming: Install a shunt across J1 Analog Dimming Control (REFI) (1-2). Adjust the potentiometer R18 to set a DC voltage on the PWMDIM pin. The PWM dimming duty cycle is set by When J2 is installed across pins 1-2, the LED current is the voltage at PWMDIM between 0.2V (0% duty) and 3V set at the maximum current. The REFI pin is connected (100% duty). Alternatively, drive the PWMDIM testpoint to VCC and in this case, the LED current is given by the with an external DC source. PWMDIM voltages above 3V following equation: set the dimming duty cycle to 100%. 220mV I = LED R14 Direct PWM dimming: Leave J1 open and connect a PWM signal to the PWMDIM testpoint. Vary the duty cycle In the case of the EV kit, I is set to 0.88A. LED to increase or decrease the intensity of the HB LED string. When J2 is installed across pins 2-3, the REFI pin is con- The PWMDIM input of the device has a 2V (max) rising nected to the voltage-divider of R1 and R2, which sets the threshold and a 0.8V (min) falling threshold and is com- REFI voltage. If V < 1.2V, then V sets the LED REFI REFI patible with 3.3V and 5V logic-level signals. Uninstall C2 current level. to achieve fast PWMDIM rise and fall edges at the IC pin. V 0.2 V ( ) REFI I = LED 5 R14 Table 1. MAX25611 EV Kit Jumper Descriptions SHUNT JUMPER DESCRIPTION POSITION Connects the PWMDIM pin of the device to VCC through a voltage divider formed by R13 1-2* and R18. The dimming duty cycle is adjusted from 0% to 100% for PWMDIM level between 0.2V and 3V. The dimming frequency is internally set at 200Hz. 2-3 Connects the PWMDIM pin to ground to disable the analog dimming function and keep the IC off. J1 Connect an external function generator to drive the PWMDIM pin with a signal from 0 to 3.3V or higher. PWMDIM pulse width should be at least above one switching period. Open Recommended PWMDIM frequency range is from 200Hz to 2kHz for visible LEDs. IR LEDs can operate at lower frequencies where flicker is not visible. 1-2* Connects VCC to the REFI pin. LED current is at the maximum value of 0.88A in this configuration. Connects the REFI pin of the device to VCC through a voltage divider formed by R1 and R2. 2-3 Adjusting R2 allows programming the LED current from 0 to 0.88A for REFI levels from 0.2V to 1.3V. J2 For REFI voltages above 1.3V, the LED current is limited at 0.88A. Connect an external voltage source to set the LED current from 0 to 0.88A for REFI levels Open from 0.2V to 1.3V. For REFI voltages above 1.3V, the LED current is limited at 0.88A. 1-2* Connects the IN pin to the same input supply as the boost power stage through a 10 filter resistor. J7 Open Connect an external supply voltage greater than 4.7V to J7 pin 2 to bias the IC IN pin. *Default position. Maxim Integrated 2 www.maximintegrated.com