5 Pin Configuration and Functions

(There is no electric signal down bonded to thermal pad inside IC. Exposed thermal pad must be soldered to PCB for optimal thermal performance.)

Figure 5-1 RHB Package 8-Pin VQFN (Top View)

Table 5-1 Pin Functions

PIN		DESCRIPTION
NO.	NAME	DESCRIPTION
1	EN3	Enable for buck3. Float to enable. Can use this pin to adjust the input undervoltage lockout of buck3 with a resistor divider.
2	PGOOD	An open drain output, asserts low if output voltage of any buck beyond regulation range due to thermal shutdown, overcurrent, undervoltage or ENx shut down.
3	RESET	Open drain power failure output signal.
4	MODE	When high, an automatic power-up/power-down sequence is provided according to states of EN1, EN2 and EN3 pins.
5	V7V	Internal LDO for gate driver and internal controller. Connect a 10-μF capacitor from the pin to power ground
6	FB2	Feedback Kelvin sensing pin for buck2 output voltage. Connect this pin to buck2 resistor divider.
7	COMP2	Error amplifier output and Loop compensation pin for buck2. Connect a series resistor and capacitor to compensate the control loop of buck2 with peak current PWM mode.
8	SS2	Soft-start and tracking input for buck2. An internal 5-μA pullup current source is connected to this pin. The soft-start time can be programmed by connecting a capacitor between this pin and ground.
9	BST2	Boot strapped supply to the high side floating gate driver in buck2. Connect a capacitor (recommend 47nF) from BST2 pin to LX2 pin.
10	LX2	Switching node connection to the inductor and bootstrap capacitor for buck2. The voltage swing at this pin is from a diode voltage below the ground up to PVIN2 voltage.
11	PGND2	Power ground connection of buck2. Connect PGND2 pin as close as practical to the (–) terminal of VIN2 input ceramic capacitor.
12	PVIN2	Input power supply for buck2. Connect PVIN2 pin as close as practical to the (+) terminal of an input ceramic capacitor (suggest 10μF).
13	PVIN3	Input power supply for buck3. Connect PVIN3 pin as close as practical to the (+) terminal of an input ceramic capacitor (suggest 10μF).
14	PGND3	Power ground connection of buck3. Connect PGND3 pin as close as practical to the (–) terminal of VIN3 input ceramic capacitor.
15	LX3	Switching node connection to the inductor and bootstrap capacitor for buck3. The voltage swing at this pin is from a diode voltage below the ground up to PVIN3 voltage.
16	BST3	Boot strapped supply to the high side floating gate driver in buck3. Connect a capacitor (recommend 47nF) from BST3 pin to LX3 pin.
17	SS3	Soft-start and tracking input for buck3. An internal 5-μA pullup current source is connected to this pin. The soft-start time can be programmed by connecting a capacitor between this pin and ground.
18	COMP3	Error amplifier output and Loop compensation pin for buck3. Connect a series resistor and capacitor to compensate the control loop of buck3 with peak current PWM mode.
19	FB3	Feedback Kelvin sensing pin for buck3 output voltage. Connect this pin to buck3 resistor divider.
20	ROSC	Oscillator frequency programmable pin. Connect an external resistor to set the switching frequency.
21	AGND	Analog ground common to buck controllers and other analog circuits. It must be routed separately from high current power grounds to the (–) terminal of bypass capacitor of input voltage VIN.
22	FB1	Feedback Kelvin sensing pin for buck1 output voltage. Connect this pin to buck1 resistor divider.
23	COMP1	Error amplifier output and Loop compensation pin for buck1. Connect a series resistor and capacitor to compensate the control loop of buck1 with peak current PWM mode.
24	SS1	Soft-start and tracking input for buck1. An internal 5-μA pullup current source is connected to this pin. The soft-start time can be programmed by connecting a capacitor between this pin and ground.
25	BST1	Boot strapped supply to the high side floating gate driver in buck1. Connect a capacitor (recommend 47nF) from BST1 pin to LX1 pin.
26	LX1	Switching node connection to the inductor and bootstrap capacitor for buck1. The voltage swing at this pin is from a diode voltage below the ground up to PVIN1 voltage.
27	PGND1	Power ground connection of Buck1. Connect PGND1 pin as close as practical to the (–) terminal of VIN1 input ceramic capacitor.
28	PVIN1	Input power supply for buck1. Connect PVIN1 pin as close as practical to the (+) terminal of an input ceramic capacitor (suggest 10μF).
29	VIN	Buck controller power supply.
30	VDIV	Input voltage threshold for power failure detection of input voltage.
31	EN1	Enable for buck1. Float to enable. Can use this pin to adjust the input undervoltage lockout of buck1 with a resistor divider.
32	EN2	Enable for buck2. Float to enable. Can use this pin to adjust the input undervoltage lockout of buck2 with a resistor divider.
	PAD	There is no electric signal down bonded to thermal pad inside IC. Exposed thermal pad must be soldered to PCB for optimal thermal performance.