33970 datasheet(10/36 Pages) FREESCALE

10 / 36 page

Analog Integrated Circuit Device Data

Freescale Semiconductor

33970

FUNCTIONAL DESCRIPTION

INTRODUCTION

FUNCTIONAL DESCRIPTION

INTRODUCTION

This 33970 is a single-packaged, Serial Peripheral

Interface (SPI) controlled, dual step motor gauge driver

integrated circuit (IC). This monolithic IC consists of four dual

output H-Bridge coil drivers and the associated control logic.

Each pair of H-Bridge drivers is used to automatically control

the speed, direction, and magnitude of current through the

two coils of a two-phase instrumentation step motor, similar

to an MMT-licensed AFIC 6405.

The 33970 is ideal for use in automotive instrumentation

systems requiring distributed and flexible step motor gauge

driving. The device also eases the transition to step motors

from air core motors by emulating the air core pointer

movement with little additional processor bandwidth

utilization.

FUNCTIONAL PIN DESCRIPTION

H-Bridge Outputs 0 (COS0+, COS0-, SIN0+, SIN0-)

Each pin is the output pin of a half bridge, designed to

source or sink current. The H-Bridge pins linearly drive the

sine and cosine coils of two separate step motors to provide

four-quadrant operation.

GROUND (GND)

These pins serve as the ground for the source of the low-

side output transistors as well as the logic portion of the

device. They also help dissipate heat from the device.

CHIP SELECT (CS)

The CS pin enables communication with the master

device. When this pin is in a logic [0] state, the 33970 is

capable of transferring information to, and receiving

information from, the master. The 33970 latches data in from

the Input Shift registers to the addressed registers on the

rising edge of CS. The output driver on the SO pin is enabled

when CS is logic [0]. When CS is logic high, signals at the

SCLK and SI pins are ignored and the SO pin is tri-stated

(high impedance). CS will only be transitioned from a logic [1]

state to a logic [0] state when SCLK is a logic [0]. CS has an

internal pull-up (lUP) connected to the pin, as specified in the

section of the Static Electrical Characteristics table entitled

CONTROL I/O, which is found on page 6.

SERIAL CLOCK (SCLK)

SCLK clocks the Internal Shift registers of the 33970

device. The Serial Input (SI) pin accepts data into the Input

Shift register on the falling edge of the SCLK signal, while the

Serial Output pin (SO) shifts data information out of the SO

Line Driver on the rising edge of the SCLK signal. It is

important that the SCLK pin be in a logic [0] state whenever

the CS makes any transition. SCLK has an internal pull down

(lDWN), as specified in the section of the Static Electrical

Characteristics table entitled CONTROL I/O, which is found

on page 6. When CS is logic [1], signals at the SCLK and SI

pins are ignored and SO is tri-stated (high impedance). Refer

to the data transfer timing diagrams in Figure 6 and Figure 7

on page 12.

SERIAL OUTPUT (SO)

The SO data pin is a tri-stateable output from the Shift

out. Those bits are followed by the message bits clocked in

FIFO, when the device is in a daisy chain connection or being

sent words that are multiples of 16 bits. Data is shifted on the

rising edge of the SCLK signal. The SO pin will remain in a

high impedance state until the CS pin is put into a logic low

state.

SERIAL INPUT (SI)

The SI pin is the input of the Serial Peripheral Interface

(SPI). Serial Input (SI) information is read on the falling edge

of SCLK. A 16-bit stream of serial data is required on the SI

pin, beginning with the most significant bit (MSB). Messages

that are not multiples of 16 bits (e.g., daisy chained device

messages) are ignored. After transmitting a 16-bit word, the

pin must be de-asserted (logic [1]) before transmitting a

new word. SI information is ignored when CS is in a logic high

state.

Multiplexed Output (RTZ)

This is a multiplexed output pin, for the non-driven coil,

during a Return to Zero (RTZ) event.

Voltage (VDD)

This SPI and logic power supply input will work with 5.0 V

supplies.

RESET (RST)

If the master decides to reset the device, or place it into a

sleep state, the RST pin is driven to a logic [0]. A logic [0] on

the RST pin will force all internal logic to the known default

state. This input has an internal active pull-up.

BATTERY VOLTAGE (VPWR)

Power supply.

33970 Datasheet(PDF) 10 Page - Freescale Semiconductor, Inc

33970 Datasheet(HTML) 10 Page - Freescale Semiconductor, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

Datasheet Download

Link URL