5 Pin Configuration and Functions

LP87743-Q1 LP87744-Q1 LP87745-Q1 RXV Package, 28-Pin VQFN-HR (Top View)

Figure 5-1 RXV Package, 28-Pin VQFN-HR (Top View)

Table 5-1 Pin Functions

PIN		I/O	TYPE	DESCRIPTION	CONNECTION IF NOT USED
NAME	NO.	I/O	TYPE	DESCRIPTION	CONNECTION IF NOT USED
SCK_SPI	1	I	Digital	Clock signal for SPI interface.	Ground
SDO_SPI	2	O	Digital	Output data signal for SPI interface.	Floating
FB_B1	3	—	Analog	Output voltage feedback (positive) for BUCK1.	Ground
CS_SPI/WD_DIS	4	I	Digital	Primary function: Chip select signal for SPI interface.	VCCA
CS_SPI/WD_DIS	4	I	Digital	Alternative programmable function: Watchdog Deactivation Input.	Not applicable
AGND	5	—	Ground	Ground.	Ground
NRSTOUT	6	O	Digital	Reset output.	Floating
nINT	7	O	Digital	Interrupt output and CAN PHY control or both.	Floating
SDI_SPI	8	I	Digital	Input data signal for SPI interface.	Ground
VIO_LDO	9	—	Analog	IO supply from the internal LDO or from external source. LDO active: regulator filter node. LDO inactive: input for connecting to an external IO supply source, with input filtering capacitor placed.	Not applicable
VOUT_BST	10	—	Analog	BOOST active: BOOST output (internally connected as VIO_LDO input). BOOST inactive and VIO_LDO inactive: short with VIO_LDO. BOOST inactive and VIO_LDO active: input for connecting to an external supply used as VIO_LDO input.	External supply
SW_BST	11	—	Analog	When BOOST active: BOOST input. When BOOST inactive: short with VOUT_BST.	VOUT_BST
PGND_B3BST	12	—	Ground	Power ground for BUCK3 and BOOST.	Ground
PVIN_B3	13	—	Power	Power input for BUCK3. The separate power pins PVIN_Bxx are not connected together internally – PVIN_Bxx and VCCA pins must be connected together in the application and be locally bypassed.	System supply
SW_B3	14	—	Analog	BUCK3 switch node.	Floating
ENABLE	15	I	Digital	Programmable ENABLE signal.	Not applicable
nERR/GPO2	16	I	Digital	Primary function: System MCU Error Monitoring Input.	Ground
		O	Digital	Alternative programmable function: General Purpose Output signal (GPO2).	Floating
		O	Digital	Alternative programmable function: Fault Communication Output signal (FAULT2).	Floating
FB_B3	17	—	Analog	Output voltage feedback (positive) for BUCK3.	Ground
VOUT_VLDO	18	—	Power	LDO regulator filter node. LDO is used for internal purposes. No external load allowed.	-
AGND	19	—	Ground	Ground.	Ground
VCCA	20	—	Power	Supply voltage for internal LDO. VCCA and PVIN_Bxx pins must be connected together in the application and be locally bypassed.	System supply
FB_B2	21	—	Analog	Output voltage feedback (positive) for BUCK2.	Ground
VMON1/GPO1	22	—	Analog	Voltage monitoring input.	Ground
		O	Digital	Alternative programmable function: General Purpose Output signal (GPO1).	Floating
		O	Digital	Alternative programmable function: Fault Communication Output signal (FAULT1).	Floating
		O	Digital	Alternative programmable function: CAN PHY control (CAN_DIS).	Floating
SYNCCLKIN	23	I	Digital	External clock input.	Ground
SW_B2	24	—	Analog	BUCK2 switch node.	Floating
PVIN_B2	25	—	Power	Power input for BUCK2. The separate power pins PVIN_Bxx are not connected together internally – PVIN_Bxx and VCCA pins must be connected together in the application and be locally bypassed.	System supply
PGND_B12	26	—	Ground	Power ground for BUCK1 and BUCK2.	Ground
PVIN_B1	27	—	Power	Power input for BUCK1. The separate power pins PVIN_Bxx are not connected together internally – PVIN_Bxx and VCCA pins must be connected together in the application and be locally bypassed.	System supply
SW_B1	28	—	Analog	BUCK1 switch node.	Floating