33937 datasheet(23/48 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33937

FUNCTIONAL DESCRIPTIONS

INTRODUCTION

FUNCTIONAL DESCRIPTIONS

INTRODUCTION

The 33937 provides an interface between an MCU and the

large FETs used to drive three phase loads. A typical load

FET may have an on resistance of 4.0 m

Ω or less and could

require a gate charge of over 400 nC to fully turn on. The IC

can operate in automotive 12 to 42 V environments.

Because there are so many methods of controlling three

phase systems, the IC enforces few constraints on driving the

FETs. It does provide deadtime (cross-over) blanking and

logic, both of which can be overridden, ensuring both FETs in

a phase are not simultaneously enabled.

An SPI port is used to configure the IC modes.

FUNCTIONAL PIN DESCRIPTION

PHASE A (PHASEA)

This pin is the totem pole output of the Phase A

comparator. This output is low when the voltage on Phase A

High Side source (source of the High Side load FET) is less

than 50 percent of VSUP.

POWER GROUND (PGND)

This pin is power ground for the charge pump. It should be

connected to VSS, however routing to a single point ground

on the PCB may help to isolate charge pump noise.

ENABLE 1 AND ENABLE 2 (EN1, EN2)

Both of these logic signal inputs must be high to enable

any gate drive output. When either or both are low, the

internal logic (SPI port, etc.) still functions normally, but all

gate drives are forced off (external power FET gates pulled

low). The signal is asynchronous.

When EN1 and EN2 return high to enable the outputs,

each LS driver must be pulsed on before the corresponding

HS driver can be commanded on. This ensures that the

bootstrap capacitors are charged.

RESET (RST)

When the reset pin is low the integrated circuit (IC) is in a

low power state. In this mode all outputs are disabled, internal

bias circuits are turned off, and a small pull-down current is

applied to the output gate drives. The internal logic will be

reset within 77 ns of RESET going low. When RST is low, the

IC will consume minimal current.

CHARGE PUMP OUT (PUMP)

This pin is the switching node of the charge pump circuit.

The output of the internal charge pump support circuit. When

the charge pump is used, it is connected to the external

pumping capacitor. This pin may be left floating if the charge

pump is not required.

CHARGE PUMP INPUT (VPUMP)

This pin is the input supply for the charge pump circuit.

When the charge pump is required, this pin should be

connected to a polarity protected supply. This input should

never be connected to a supply greater than 40 V.

If the charge pump is not required this pin may be left

floating.

VSUP INPUT (VSUP)

The supply voltage pin should be connected to the

common connection of the High Side FETs. It is the reference

bias for the Phase Comparators and Desaturation

Comparator. It is also used to provide power to the internal

steady state trickle charge pump and to energize the hold off

circuit.

PHASE B (PHASEB)

This pin is the totem pole output of the Phase B

comparator. This output is low when the voltage on Phase B

High Side source (source of the High Side load FET) is less

than 50 percent of VSUP.

PHASE C (PHASEC)

This pin is the totem pole output of the Phase C

comparator. This output is low when the voltage on Phase C

High Side source (source of the High Side load FET) is less

than 50 percent of VSUP.

PHASE A HIGH SIDE INPUT (PA_HS)

This input logic signal pin enables the High Side Driver for

Phase A. The signal is active low, and is pulled up by an

internal current source.

PHASE A LOW SIDE INPUT (PA_LS)

This input logic signal pin enables the Low Side Driver for

Phase A. The signal is active high, and is pulled down by an

internal current sink.

VDD VOLTAGE REGULATOR (VDD)

VDD is an internally generated 5.0 V supply. The internal

regulator provides continuous power to the IC and is a supply

reference for the SPI port. A 0.47 µF (min) decoupling

capacitor must be connected to this pin.

This regulator is intended for internal IC use and can

supply only a small (1.0 mA) external load current.

33937 Datasheet(PDF) 23 Page - Freescale Semiconductor, Inc

33937 Datasheet(HTML) 23 Page - Freescale Semiconductor, Inc

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