9

FN8154.0

Power Supply Failure Conditions

Should there be a power failure of VDDH, GATE_H,

GATE_M and GATE_L charge pumps are all turned OFF

Should there be a failure of the VDDM supply, the GATE_M

charge pump turns OFF.

Should there be a failure of the VDDL supply, the GATE_L

and GATE_M charge pumps both turn off when VDDL falls

Remote Monitoring Functions

The X80200 can monitor the status of the GATE_H,

GATE_M, and GATE_L charge pump control signals. This

allows an indirect way to monitor system voltages. The

volatile status bits: Stat_GATEH, Stat_GATEM, and

Stat_GATEL indicate the status of GATE_H, GATE_M and

GATE_L output control signals, respectively. If the bit is a “1”,

then the charge pump is being turned on. If the bit is a “0”,

the output is turned off. Since the bits reflect the internal

control signal and not the state of the output, external

loading that prevents the charge pump from reaching the

desired FET gate drive voltage will not be detected by

reading the register.

These status bits can be read via the 2-wire serial bus. Refer

to Status Register section for more information on how to

read this register.

Several X80200 devices can be used to monitor many

system voltages on different system cards on a backplane.

Each X80200 has 3 slave address pins allowing up to 8

X80200 to be used on the same bus.

X80200 provides the user the ability to remotely turn-off the

gates through software. (See "Remote Shutdown Register

(RSR) (Volatile)" on page 10 for more information.)

SETV

FET “L”

GATE_M

GATE_L

(VFB)

DRAIN

REF

REF

FIGURE 5. VOLTAGE BASED SEQUENCING OF GATE_M

AND GATE_L

VDDH

VDDM

VDDL

GATE_H

GATE_M

GATE_L

VDDH

VDDM

VDDL

FAILS

FAILS

FAILS

FIGURE 6. GATE CONTROL DURING INDIVIDUAL POWER

FAIL CONDITIONS

X80200, X80201, X80202, X80203, X80204