MAX25601A/MAX25601B/ Synchronous Boost and MAX25601C/MAX25601D Synchronous Buck LED Controllers Pin DescriptionPINNAMEFUNCTIONTQFNTSSOP 1 4 IN Supply Input for VDRV regulator. Connect a 0.1µF ceramic capacitor from this pin to PGND. If an external bias is used, then connect IN to VDRV. 2 5 PGND Power Ground +5V Regulator Output and Driver Supply. Connect a 4.7μF ceramic capacitor from 3 6 VDRV VDRV to PGND. If an external bias is used, then connect IN to VDRV, and connect the external supply to VDRV. 4 — NC Not Internally Connected High-Side Power Supply for High-Side Gate Drive of Buck LED Regulator. Connect 5 7 BST2 a 0.1μF ceramic capacitor from BST2 to LX2, and a BST diode between VDRV and BST2. High Side Driver of Buck LED Regulator. Connect to gate of the buck regulator's 6 8 DH2 high-side n-channel MOSFET. Use series resistor to limit current slew rate and mitigate EMI noise, if required. 7 9 LX2 Switching Node of Buck LED Regulator Low-Side Driver of Buck LED Regulator. Connect to gate of the buck regulator’s low-side n-channel MOSFET. Use series resistor to limit current slew rate and mitigate EMI noise, if necessary. During startup, DL2 is used to select the slope compensation of the boost regulator based on the following options: 8 10 DL2 DL2 RESISTOR TO PGNDSLOPE COMPENSATION SELECTION 100kΩ Larger slope compensation for boost output voltages greater than 45V 30kΩ Smaller slope compensation for boost output voltages less than 45V 9 11 OUT Feedback Voltage of Buck. Connect a resistor-divider from this pin to the output volt- age on buck. This pin has the scaled-down feedback of the output voltage of the buck. 10 12 CSP Positive Current-Sense Input for Buck Regulator. Connect a resistor from this pin to CSN to sense the buck regulator inductor current. 11 13 UVEN Input UVLO and Enable Pin. Dual-function pin to set the input UV threshold, or to use as an enable input. The UVEN threshold is set at 1.24V (typ). 12 14 CSN Negative Current-Sense Input for Buck Regulator 13 --- NC Not Internally Connected Analog Dimming Input for Buck LED Regulator. The voltage at REFI sets the LED 14 15 REFI current.Connect a resistor-divider from VCC to set the default LED current. Alternatively, drive REFI with an external voltage source for analog dimming. ILED = (VREFI - 0.2)/(5 x RCS_LED) www.maximintegrated.com Maxim Integrated │ 10