MP1922 – 100V, 3A, SINGLE-CHANNEL, HALF-BRIDGE PRE-DRIVER IC

MP1922 Rev. 1.0

www.MonolithicPower.com

12

9/10/2021

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OPERATION

The

MP1922

is

a

100V,

single-channel,

integrated circuit (IC) half-bridge pre-driver for

driving two N-channel power MOSFETs with up

to 3A source and 4A sink current capability. The

device also supports output supply voltages up

to 100V.

The MP1922 features low-power sleep mode,

which disables the device and draws a very low

supply current. It also provides flexible functions

such

as

configurable

output

slew

rate,

adjustable

dead-time

control,

and

output

desaturation detection, which allow the device

to be used in many applications.

Start-Up

Start-up is initiated by the application of voltage

to the VG pin.

To initiate start-up, the VG voltage (VG), which

is the power supply voltage for the MP1922,

must exceed the VUVLO threshold (about 3.1V).

After VG exceeds this threshold, the MP1922

turns on the internal circuitry, including the high-

side gate drive charge pump.

If auto-refresh is enabled at start-up and the AR

pin is grounded, then the MP1922 initiates a

bootstrap (BST) charge cycle by briefly turning

off the high-side

MOSFET

(HS-FET)

and

turning on the low-side MOSFET (LS-FET)

during start-up.

If the output is commanded high (INH = H, INL

= L) before the BST charge process is complete,

then a fault may be triggered due to insufficient

gate drive voltage for fully turning on the HS-

FET. If auto-refresh is not enabled, then the LS-

FET should be turned on for at least a few

microseconds

to

quickly

charge

the

BST

capacitor (CBST). Relying on the internal charge

pump

to

initially

charge

CBST

is

not

recommended due to limited current capability

and the time required to provide sufficient

charge to the capacitor.

The start-up process takes between 1ms and

2ms.

Sleep Operation

By driving nSLEEP low, the device enters a

low-power sleep state, in which all internal

circuits are disabled and all inputs are ignored.

To wake up from sleep mode, about 1ms must

pass for the circuits to initialize and for the gate

drive charge pump to start up before the device

drives the FETs.

Input Logic

The INH input pin is used to control the HS-FET

gate drive. The INL pin controls the LS-FET

gate drive. Positive dead time is enforced by

the device. If both INH and INL are driven high,

then neither FET is driven (see Table 1).

Table 1: Input Logic

INL

INH

OUT

H

H

High impedance

H

L

GND

L

H

VIN

L

L

High impedance

The ENBL pin enables the outputs. When

ENBL is low, both the high-side (HS) and low-

side (LS) gate drive outputs are pulled to

ground, disabling both output FETs. The ENBL

input can be used for fast protection circuits.

nFAULT

The nFAULT pin reports to the system when a

fault condition, such as output FET desaturation

or over-temperature (OT), is detected. nFAULT

is an open-drain output, and is pulled low when

a fault occurs. If the fault condition is reset by

de-asserting ENBL, removing VG, or activating

nSLEEP, then the nFAULT pin is pulled high by

the external pull-up resistor.

The nFAULT pin can be connected to the ENBL

input pin and a pull-up resistor to make the

MP1922 automatically restart after a fault.

When a fault occurs, the nFAULT pin pulls the

ENBL pin low, which resets the fault condition.

After this reset, the pull-up resistor pulls ENBL

high again.

Adding a capacitor in parallel with the pull-up

resistor introduces a delay in re-enabling the

MP1922 and extends the retry cycle. The RC

time constant sets the retry delay.