TPS51222

SLUS908 – JANUARY 2009............................................................................................................................................................................................... www.ti.com

PIN FUNCTIONS (continued)

PIN

I/O

DESCRIPTION

NAME

NO.

SKIPSEL1

6

Skip mode selection pin.

GND: Continuous conduction mode

I

VREF2: Auto Skip

SKIPSEL2

19

VREG3: OOA Auto Skip, maximum 7 skips (suitable for fsw < 400kHz)

VREG5: OOA Auto Skip, maximum 15 skips (suitable for equal to or greater than 400kHz)

SW2

25

I/O

High-side MOSFET gate driver returns.

SW1

32

VREG5 switchover power supply input pin. When EN1 is high, PGOOD1 indicates GOOD and V5SW

voltage is higher than 4.8 V, switch-over function is enabled.

V5SW

2

I

Note: When switch-over is enabled, VREG5 output voltage is approximately equal to the V5SW input

voltage.

VBST1

31

Supply inputs for high-side N-channel FET driver (boot strap terminal). Connect a capacitor (0.1-

µF or

I

greater is recommended) from this pin to respective SW terminal. Additional SB diode from VREG5 to this

VBST2

26

pin is an optional.

VFB1

9

SMPS voltage feedback Inputs. Connect the feedback resistors divider, and should be referred to (signal)

I

GND.

VFB2

16

VIN

23

I

Supply input for 5-V and 3.3-V linear regulator. Typically connected to VBAT.

VREF2

13

O

2-V reference output. Bypass to (signal) GND with 0.22-

µF of ceramic capacitance.

Always alive 3.3 V, 10 mA low dropout linear regulator output. Bypass to (signal) GND with more than 1-

µF

VREG3

22

O

ceramic capacitance. Runs from VIN supply or from VREG5 when it is switched over to V5SW input.

5-V, 100-mA low dropout linear regulator output. Bypass to (power) GND using a 10-

µF ceramic capacitor.

Runs from VIN supply. Internally connected to VBST and DRVL. Shuts off with EN. Switches over to V5SW

VREG5

29

O

when 4.8 V or above is provided.

Note: When switch-over (see above V5SW) is enabled, VREG5 output voltage is approximately equal to

V5SW input voltage.

8

Submit Documentation Feedback

Copyright © 2009, Texas Instruments Incorporated

Product Folder Link(s) :TPS51222