LTC1154 datasheet(5/16 Pages) LINER

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LTC1154

ENABLE Threshold Voltage

Shutdown Threshold Voltage

Gate Drive Current

HARA TERISTICS

TYPICALPERFOR

PI FU CTIO S

Input and Shutdown Pins

The LTC1154 input pin is active high and activates all of the

protection and charge pump circuitry when switched ON.

The shutdown pin is designed to immediately disable the

switch if a secondary fault condition (over temperature,

etc.) is detected. The LTC1154 logic and shutdown inputs

are high impedance CMOS gates with ESD protection

diodes to ground and supply and therefore should not be

forced beyond the power supply rails. The shutdown pin

should be connected to ground when not in use.

ENABLE Input Pin

The ENABLE input can be used to enable a number of

LTC1154 high-side switches in banks or to provide a

secondary means of control. It can also act as an inverting

input. The ENABLE input is a high impedance CMOS gate

with ESD clamp diodes to ground and supply and there-

fore should not be forced beyond the power supply rails.

This pin should be grounded when not in use.

Gate Drive Pin

The gate drive pin is either driven to ground when the

switch is turned OFF or driven above the supply rail when

the switch is turned ON. This pin is a relatively high

impedance when driven above the rail (the equivalent of a

few hundred k

Ω). Care should be taken to minimize any

loading of this pin by parasitic resistance to ground or

supply.

Supply Pin

The supply pin of the LTC1154 serves two vital purposes.

The first is obvious: it powers the input, gate drive, regu-

lation and protection circuitry. The second purpose is less

obvious: it provides a Kelvin connection to the top of the

drain sense resistor for the internal 100mV reference.

The LTC1154 is designed to be continuously powered so

that the gate of the MOSFET is actively driven at all times.

If it is necessary to remove power from the supply pin and

then re-apply it, the input pin (or enable pin) should be

cycled a few milliseconds

after the power is re-applied to

reset the input latch and protection circuitry. Also, the

input and enable pins should be isolated with 10k resistors

to limit the current flowing through the ESD protection

diodes to the supply pin.

The supply pin of the LTC1154 should never be forced

below ground as this may result in permanent damage to

the device. A 300

Ω resistor should be inserted in series

with the ground pin if negative supply voltage transients

are anticipated.

TEMPERATURE (°C)

–50

0.4

0.6

1.O

1.2

1.4

2.4

1.8

LTC1154 • TPC13

0.8

2.0

2.2

1.6

–25

100

125

VS = 18V

VS = 5V

TEMPERATURE (°C)

–50

0.5

1.5

2.0

2.5

5.0

3.5

LTC1154 • TPC14

1.0

4.0

4.5

3.0

–25

100

125

VS = 12V

DISABLE

ENABLE

GATE VOLTAGE ABOVE SUPPLY (V)

100

1000

0.1

LTC1154 • TPC15

VS = 18V

TA = 25°C

VS = 12V

VS = 5V

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