33937 datasheet(23/47 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33937

FUNCTIONAL DESCRIPTIONS

INTRODUCTION

A power-on-reset (POR) circuit monitors this pin and until

the voltage rises above the threshold, the internal logic will be

reset; driver outputs will be tri-stated and SPI communication

disabled.

The VDD regulator can be disabled by asserting the RST

signal low. The VDD regulator is powered from the VPWR

pin.

PHASE B HIGH SIDE CONTROL INPUT (PB_HS)

This pin is the input logic signal, enabling the High Side

driver for Phase B. The signal is active low, and is pulled up

by an internal current source.

PHASE B LOW SIDE INPUT (PB_LS)

This pin is the input logic signal, enabling the Low Side

driver for Phase B. The signal is active high, and is pulled

down by an internal current sink.

INTERRUPT (INT)

The Interrupt pin is a totem pole logic output. When a fault

is detected, this pin will pull high until it is cleared by

executing the Clear Interrupt command via the SPI port. The

faults capable of causing an interrupt can be masked via the

MASK0 and MASK1 SPI registers to customize the

response.

CHIP SELECT (CS)

Chip select is a logic input that frames the SPI commands

and enables the SPI port. This signal is active low, and is

pulled up by an internal current source.

SERIAL IN (SI)

The Serial In pin is used to input data to the SPI port.

Clocked on the falling edge of SCLK, it is the most significant

bit (MSB) first. This pin is pulled down by an internal current

sink.

SERIAL CLOCK (SCLK)

This logic input is the clock is used for the SPI port. The

SCLK typically runs at 3.0 MHz (up to 5.0 MHz) and is pulled

down by an internal current sink.

SERIAL OUT (SO)

Output data for the SPI port streams from this pin. It is tri-

stated until CS is low. New data appears on rising edges of

SCLK in preparation for latching by the falling edge of SCLK

on the master.

PHASE C LOW SIDE INPUT (PC_LS)

This input logic pin enables the Low Side Driver for Phase

C. This pin is an active high, and is pulled down by an internal

current sink.

PHASE C HIGH SIDE INPUT (PC_HS)

This input logic pin enables the High Side Driver for Phase

C. This signal is active low, and is pulled up by an internal

current source.

AMPLIFIER OUTPUT (AMP_OUT)

This pin is the output for the current sensing amplifier. It is

also the sense input to the over-current comparator.

AMPLIFIER INVERTING INPUT (AMP_N)

The inverting input to the current sensing amplifier.

AMPLIFIER NON-INVERTING INPUT (AMP_P)

The non-inverting input to the current sensing amplifier.

OVER-CURRENT COMPARATOR OUTPUT

(OC_OUT)

The over-current comparator output is a totem pole logic

level output. A logic high indicates an over-current condition.

OVER-CURRENT COMPARATOR THRESHOLD

(OC_TH)

This input sets the threshold level of the over-current

comparator.

VOLTAGE SOURCE SUPPLY (VSS)

VSS is the ground reference for the logic interface and

power supplies.

GROUND (GND0,GND1)

These two pins are connected internally to VSS by a 1.0

resistor. They provide device substrate connections and also

the primary return path for ESD protection.

VLS REGULATOR CAPACITOR (VLS_CAP)

This connection is for a capacitor which will provide a low-

impedance for switching currents on the gate drive. A low

ESR decoupling capacitor, capable of sourcing the pulsed

drive currents must be connected between this pin and VSS.

Use the 33937A to avoid the CAUTION on page 27 for

capacitances greater than 3.5 µF.

This is the same DC node as VLS, but it is physically

placed on the opposite end of the IC to minimize the source

impedance to the gate drive circuits.

PHASE C LOW SIDE SOURCE (PC_LS_S)

The phase C 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 C.

PHASE C LOW SIDE GATE (PC_LS_G)

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

It provides high current through a low impedance to turn on

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