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DEVICE INFORMATION

24

23

22

21

20

19

PGND1

TRIP1

V5IN

V5FILT

TRIP2

PGND2

VO1

VFB1

GND

TONSEL

VFB2

VO2

48

17

16

15

14

13

1

2

3

4

5

6

7

8

9

10

11

12

QFN PACKAGE

(TOP VIEW)

TPS51124

SLVS616A – NOVEMBER 2005 – REVISED NOVEMBER 2005

TERMINAL FUNCTIONS

TERMINAL

I/O

DESCRIPTION

NAME

NO.

DRVH1

21

Synchronous high-side MOSFET driver outputs. LL node referenced floating drivers. The gate drive

O

voltage is defined by the voltage across VBST to LL node flying capacitor.

DRVH2

10

DRVL1

19

Synchronous low-side MOSFET driver outputs. PGND referenced drivers. The gate drive voltage is

O

defined by V5IN voltage.

DRVL2

12

EN1

23

I

Channel 1 and channel 2 enable pins. Connect to 5 V or 3.3 V to turn on SMPS

EN2

8

GND

3

I

Signal ground pin

LL1

20

Switch node connections for high-side drivers return. Also serve as input to current comparators and input

I/O

voltage monitor for on-time control circuitry.

LL2

11

PGND1

18

Ground returns for DRVL1 and DRVL2. Also serve as input of current comparators. Connect PGND1,

I/O

PGND2, and GND strongly together near the IC. Output discharge current flows through this pin, also.

PGND2

13

PGOOD1

24

Power Good window comparator open drain output for channel 1 and 2. Pull up with a resistor to 5 V, or

O

appropriate signal voltage. Current capability is 5 mA. PGOOD goes high 0.5 ms after VFB comes within

PGOOD2

7

specified limits. Power bad, or the terminal goes low, is within 10

µs.

TONSEL

4

I

On-time selection pin. See Table 1.

TRIP1

17

Over-current trip point set input. Connect resistor from this pin to GND to set threshold for synchronous

I

TRIP2

14

over-current comparator.

VBST1

22

Supply input for synchronous high-side MOSFET driver (Boost Terminal). Connect capacitor from this pin

I

to respective LL terminals. An internal PN diode is connected between V5IN to each of these pins. User

VBST2

9

can add external Schottky diode if forward drop is critical to drive the MOSFET.

VFB1

2

I

SMPS voltage feedback inputs. Connect with feedback resistor divider.

VFB2

5

VO1

1

Output connections to SMPS. These terminals serve two functions: On-time adjustment and output

I

discharge.

VO2

6

5-V power supply input for the entire control circuit except the MOSFET drivers. Connect RC low-pass

V5FILT

15

I

filter from V5IN to V5FILT.

V5IN

16

I

5-V power supply input for FET gate drivers. Internally connected to VBSTx by PN diodes.

5