TPS2811, TPS2812, TPS2813, TPS2814, TPS2815

DUAL HIGH-SPEED MOSFET DRIVERS

SLVS132D – NOVEMBER 1995 – REVISED NOVEMBER 1997

24

POST OFFICE BOX 655303

APPLICATION INFORMATION

synchronous buck regulator

Figure 48 is the schematic for a 100-kHz synchronous-rectified buck converter implemented with a TL5001

pulse-width-modulation (PWM) controller and a TPS2812 driver. The bill of materials is provided in Table 1. The

converter operates over an input range from 5.5 V to 12 V and has a 3.3-V output capable of supplying 3 A

continuously and 5 A during load surges. The converter achieves an efficiency of 90.6% at 3 A and 87.6% at

5 A. Figures 49 and 50 show the power switch switching performance. The output ripple voltage waveforms are

documented in Figures 54 and 55.

The TPS2812 drives both the power switch, Q2, and the synchronous rectifier, Q1. Large shoot-through

currents, caused by power switch and synchronous rectifier remaining on simultaneously during the transitions,

are prevented by small delays built into the drive signals, using CR2, CR3, R11, R12, and the input capacitance

of the TPS2812. These delays allow the power switch to turn off before the synchronous rectifier turns on and

vice versa. Figure 51 shows the delay between the drain of Q2 and the gate of Q1; expanded views are provided

in Figures 52 and 53.

REG_IN

1 IN

GND

2 IN

REG_OUT

1 OUT

2 OUT

U2

TPS2812D

1

2

3

4

8

7

6

5

Q1

IRF7406

1

3

2

R5

10 k

Ω

C11

0.47

µF

C100

100

µF

16 V

C5

100

µF

16 V

1

2

3

4

J1

2

1

Q2

IRF7201

3

CR1

30BQ015

C6

1000 pF

R7

3.3

Ω

L1

27

µF

C12

100

µF

16 V

C7

100

µF

16 V

C13

10

µF

10 V

1

2

3

4

J2

GND

GND

3.3 V

3.3 V

GND

GND

U1

TL5001CD

OUT

COMP

FB

GND

RT

DTC

SCP

R2

1.6 k

Ω

C3

0.0022

µF

C2

0.033

µF

R13

10 k

Ω

C14

0.1

µF

R6

15

Ω

R10

1 k

Ω

R11

30 k

Ω

CR2

BAS16ZX

R12

10 k

Ω

CR3

BAS16ZX

C15

1

µF

R8

121 k

Ω

1%

C9

0.22

µF

C1

1

µF

R4

2.32 k

Ω

1%

R3

180

Ω

C4

0.022

µF

R1

1.00 k

Ω

1%

R9

90.9 k

Ω

1%

8765

1234

+

+

++

+

Figure 48. 3.3-V 3-A Synchronous-Rectified Buck Regulator Circuit