LTC4444

7

4444f

BLOCK DIAGRAM

3

6

7

9

HIGH SIDE

LEVEL SHIFTER

LDO

GND

7.2V TO

13.5V

BOOST

UP TO 100V

TG

8

TS

BG

4444 BD

1

TINP

BINP

2

5

NC

LOW SIDE

LEVEL SHIFTER

ANTISHOOT-THROUGH

PROTECTION

4

TIMING DIAGRAM

90%

INPUT RISE/FALL TIME < 10ns

TINP (BINP)

BG (TG)

BINP (TINP)

TG (BG)

90%

90%

10%

4444 TD

10%

10%

OPERATION

Overview

The LTC4444 receives ground-referenced, low voltage

digital input signals to drive two N-channel power MOSFETs

in a synchronous buck power supply configuration. The

depending on the state of the input. Similarly, the gate of

the high side MOSFET is driven to either BOOST or TS by

a supply bootstrapped off of the switching node (TS).

Input Stage

The LTC4444 employs CMOS compatible input thresholds

that allow a low voltage digital signal to drive standard

power MOSFETs. The LTC4444 contains an internal

voltage regulator that biases both input buffers for high

side and low side inputs, allowing the input thresholds

false triggering due to noise during switching transitions.

However, care should be taken to keep both input pins

(TINP and BINP) from any noise pickup, especially in high

frequency, high voltage applications. The LTC4444 input

buffers have high input impedance and draw negligible

input current, simplifying the drive circuitry required for

the inputs.