LTC4367 datasheet(12/30 Pages) AD

12 / 30 page

LTC7000A

Rev. 0

For more information www.analog.com

OPERATION

The LTC7000A/LTC7000A-1 is designed to receive a

ground-referenced, low voltage digital input signal, INP

and quickly drive and protect a high side N-channel power

MOSFET whose drain can be up to 150V above ground.

The LTC7000A/LTC7000A-1 is capable of driving a 1nF

load using a 12V bootstrapped supply voltage (VBST–VTS)

with 35ns of propagation delay and fast rise/fall times.

The high gate drive voltage reduces external power

losses associated with external MOSFET on-resistance.

The strong drivers not only provide fast turn on and off

times but hold the TGUP and TGDN to TS voltages in the

desired state in the presence of high slew rate transients

which can occur driving inductive loads at high voltages.

Overcurrent Protection

The LTC7000A/LTC7000A-1 protects a high side

N-channel MOSFET from an overcurrent condition by

monitoring the voltage across an external sense resistor

placed in series with the drain of an external MOSFET

and forcing the external MOSFET to turn off by pulling

TGDN to TS when the voltage across the sense resistor,

ΔVSNS, exceeds the current comparator threshold

voltage, ΔVTH, after a period of time set by the timing

capacitor, CT. When an overcurrent condition is detected

with ISET open, ΔVTH is internally programmed to a low

value of 30mV minimizing the external conduction loss

associated with current sensing by allowing the use of

lower value sense resistors. A resistor placed between

ISET and ground allows ΔVTH to be programmed from

20mV to 75mV.

An adjustable fault and overcurrent timer is enabled by

placing a capacitor, CT from the TIMER pin to ground

and allows the load to continue functioning during

brief overcurrent transient events while protecting the

MOSFET from long periods of high currents. An external

fault flag is available which can warn of an impending

MOSFET turn off. A fast turn-off mode where TGDN

is immediately pulled to TS due to an overcurrent is

available by connecting the TIMER pin to VCC.

Current Monitor (LTC7000A Only)

The LTC7000A provides an output voltage referenced to

ground on the IMON pin that reflects the current flowing

through the external sense resistor connected between

SNS+ and SNS– while TGUP is high. The voltage on IMON

is the voltage difference between the SNS+ and SNS– pins

multiplied by 20x and referenced to ground with a range

of 0V to 1.5V. The IMON output voltage has an output

impedance of 100kΩ and is pulled to ground with a

100kΩ resistor when INP is low.

VCC Power

Power for the MOSFET driver and internal circuitry is

derived from the VCC pin. The VCC pin voltage is gener-

ated from an internal P-channel LDO connected to VIN.

VCC can also be overdriven from a high efficiency exter-

nal source for high frequency switching applications that

require higher power delivered to external MOSFET. VCC

should never be driven higher than VIN or permanent

damage to the LTC7000A/LTC7000A-1 could occur.

(Refer to Block Diagram)

TIMING DIAGRAM

INPUT (INP)

OUTPUT (TG-TS)

INPUT RISE/FALL TIME < 10ns

tPLH

tPHL

90%

10%

VIH

VIL

7000A TD

LTC4367 数据表(PDF) 12 Page - Analog Devices

LTC4367 数据表(HTML) 12 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

数据表下载