33937 datasheet(24/47 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33937

FUNCTIONAL DESCRIPTIONS

INTRODUCTION

and off the Low Side FET.. A low-impedance drive ensures

transient currents do not overcome an off-state driver and

allow pulses of current to flow in the external FET. This output

has also been designed to resist the influence of negative

currents.

PHASE C HIGH SIDE SOURCE (PC_HS_S)

The source connection for the phase C High Side output

FET is the reference voltage for the gate drive on the High

Side FET and also the low voltage end of the bootstrap

capacitor.

PHASE C HIGH SIDE GATE (PC_HS_G)

This is the gate drive for the phase C High Side output

FET. This pin provides the gate bias to turn the external FET

on or off. The gate voltage is limited to about 15 V above the

FET source voltage. A low-impedance drive is used, ensuring

transient currents do not overcome an off-state driver and

allow pulses of current to flow in the external FETs. This

output has also been designed to resist the influence of

negative currents.

PHASE C BOOTSTRAP (PC_BOOT)

This is the bootstrap capacitor connection for phase C. A

capacitor connected between PC_HS_S and this pin

provides the gate voltage and current to drive the external

FET gate. Typically, the boostrap capacitor selection is 10 to

20 times the gate capacitance. The voltage across this

capacitor is limited to about 15 V. Use the 33937A to avoid

the CAUTION on page 27 for bootstrap capacitances greater

than 100 nF.

PHASE B LOW SIDE SOURCE (PB_LS_S)

The phase B Low Side source is the pin used to return the

gate currents from the Low Side FET. Best performance is

realized by connecting this node directly to the source of the

Low Side FET for phase B.

PHASE B LOW SIDE GATE (PC_LS_G)

This is the gate drive for the phase B Low Side output FET.

It provides high current through a low impedance to turn on

and off the Low Side FET. A low-impedance drive ensures

transient currents do not overcome an off-state driver and

allow pulses of current to flow in the external FET. This output

has also been designed to resist the influence of negative

currents.

PHASE B HIGH SIDE SOURCE (PB_HS_S)

The source connection for the phase B High Side output

FET is the reference voltage for the gate drive on the High

Side FET and also the low voltage end of the bootstrap

capacitor.

PHASE B HIGH SIDE GATE (PB_HS_G)

This is the gate drive for the phase B High Side output

FET. This pin provides the gate bias to turn the external FET

on or off. The gate voltage is limited to about 15 V above the

FET source voltage. A low-impedance drive is used, ensuring

transient currents do not overcome an off-state driver and

allow pulses of current to flow in the external FETs. This

output has also been designed to resist the influence of

negative currents.

PHASE B BOOTSTRAP (PB_BOOT)

This is the bootstrap capacitor connection for phase B. A

capacitor connected between PC_HS_S and this pin

provides the gate voltage and current to drive the external

FET gate. Typically, the boostrap capacitor selection is 10 to

20 times the gate capacitance. The voltage across this

capacitor is limited to about 15 V. Use the 33937A to avoid

the CAUTION on page 27 for bootstrap capacitances greater

than 100 nF.

PHASE A LOW SIDE SOURCE (PA_LS_S)

The phase A Low Side source is the pin used to return the

gate currents from the Low Side FET. Best performance is

realized by connecting this node directly to the source of the

Low Side FET for phase A.

PHASE A LOW SIDE GATE (PA_LS_G)

This is the gate drive for the phase A Low Side output FET.

It provides high current through a low impedance to turn on

and off the Low Side FET. A low-impedance drive ensures

transient currents do not overcome an off-state driver and

allow pulses of current to flow in the external FET. This output

has also been designed to resist the influence of negative

currents.

PHASE A HIGH SIDE SOURCE (PA_HS_S)

The source connection for the phase A High Side output

FET is the reference voltage for the gate drive on the High

Side FET and also the low voltage end of the bootstrap

capacitor.

PHASE A HIGH SIDE GATE (PA_HS_G)

This is the gate drive for the phase A High Side output

FET. This pin provides the gate bias to turn the external FET

on or off. The gate voltage is limited to about 15 V above the

FET source voltage. A low-impedance drive is used, ensuring

transient currents do not overcome an off-state driver and

allow pulses of current to flow in the external FETs. This

output has also been designed to resist the influence of

negative currents.

PHASE A BOOTSTRAP (PA_BOOT)

This is the bootstrap capacitor connection for phase A. A

capacitor connected between PC_HS_S and this pin

provides the gate voltage and current to drive the external

FET gate. Typically, the boostrap capacitor selection is 10 to

20 times the gate capacitance. The voltage across this

capacitor is limited to about 15 V. Use the 33937A to avoid

the CAUTION on page 27 for bootstrap capacitances greater

than 100 nF.

33937 Datasheet(PDF) 24 Page - Freescale Semiconductor, Inc

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