TPS5120Q1

DUAL OUTPUT, TWOPHASE SYNCHRONOUS BUCK DC/DC CONTROLLER

SGLS225B − JANUARY 2004 − REVISED APRIL 2008

4

POST OFFICE BOX 655303

Terminal Functions

TERMINAL

I/O

DESCRIPTION

NAME

NO.

I/O

DESCRIPTION

CT

5

I/O

External capacitor from CT to GND for adjusting the triangle oscillator

FB1

2

O

Feedback output of CH1 error amplifier

FB2

14

O

Feedback output of CH2 error amplifier

GND

7

Control GND

INV1

1

I

Inverting input of the CH1 error amplifier, skip comparator, and OVP1/UVP1 comparator

INV2

15

I

Inverting input of the CH2 error amplifier, skip comparator, and OVP2/UVP2 comparator

LH1

30

I/O

Bootstrap capacitor connection for CH1 high-side gate drive

LH2

16

I/O

Bootstrap capacitor connection for CH2 high-side gate drive

LL1

28

I/O

Bootstrap this pin low for CH1 high-side gate driving return and output current protection. Connect this pin to

the junction of the high-side and low-side FETs for a floating drive configuration.

LL2

18

I/O

Bootstrap this pin low for CH2 high-side gate driving return and output current protection. Connect this pin to

the junction of the high-side and low-side FETs for a floating drive configuration.

OUT1_d

27

O

Gate drive output for CH1 low-side gate drive

OUT2_d

19

O

Gate drive output for CH2 low-side gate drive

OUT1_u

29

O

Gate drive output for CH1 high-side switching FETs

OUT2_u

17

O

Gate drive output for CH2 high-side switching FETs

OUTGND1

26

Ground for CH1 FET drivers

OUTGND2

20

Ground for CH2 FET drivers

POWERGOOD

12

O

Power good open-drain output. When low, POWERGOOD reports an output fail condition. PG comparators

monitor both SMPS’s over voltage and UVLO of VREF5. The threshold is

±7%. When the SMPS starts up, the

POWERGOOD pin’s output goes high. POWERGOOD also monitors VREF5’s UVLO output.

PWM/SKIP

4

I

PWM/SKIP mode select pin. The PWM/SKIP pin is used to change the output’s operating mode. If this terminal

is lower than 0.5 V, it works in PWM mode. When a minimum voltage of 2 V is applied, the device operates in

skip mode. In light load condition (< 0.2 A), the skip mode gives a short pulse to the low-side FETs instead of a

full pulse. With this control, switching frequency is lowered and switching loss is reduced. Also, the output

capacitor energy discharging through the output inductor and low-side FETs is stopped. Therefore, TPS5120

achieves a higher efficiency in light load conditions.

REF

8

O

0.85-V reference voltage output. The 0.85-V reference voltage is used for setting the output voltage and the

voltage protection. This reference voltage is dropped down from a 5-V regulator.

REG5V_IN

21

I

External 5-V input

FLT

11

I/O

Fault latch timer pin. An external capacitor is connected between FLT and GND to set the FLT enable time up.

SOFTSTART1

3

I/O

External capacitor from SOFTSTART1 to GND for CH1 softstart control. Separate soft-start terminals make it

possible to set the start-up time of each output independently.

SOFTSTART2

13

I/O

External capacitor from SOFTSTART2 to GND for CH2 softstart control. Separate soft-start terminals make it

possible to set the start-up time of each output independently.

STBY1

9

I

Standby control for CH1. SMPS1 can be switched into standby mode separately by grounding the STBY1 pin.

STBY2

10

I

Standby control for CH2. SMPS2 can be switched into standby mode separately by grounding the STBY2 pin.

TRIP1

25

I

External resistor connection for CH1 output current control

TRIP2

23

I

External resistor connection for CH2 output current control

VCC

24

Supply voltage input

VREF5

22

O

5-V internal regulator output

5V_STBY

6

I

5-V linear regulator control