34921 datasheet(19/36 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

34921

FUNCTIONAL DESCRIPTION

FUNCTIONAL TERMINAL DESCRIPTION

and thermal shutdown protection. It is typically used to supply

a micro processor core or embedded DRAM.

DC MOTOR A OUTPUT A (ADCMA)

A high-side and low-side driver output terminal, which

when combined with ADCMB forms the A H-bridge DC motor

driver. The driver is PWM controlled via the APWM input, and

direction controlled via the Serial I/O. It features current limit

and thermal shutdown protection.

DC MOTOR A OUTPUT B (ADCMB)

A high-side and low-side driver output terminal, which

when combined with ADCMA forms the A H-bridge DC motor

driver. The driver is PWM controlled via the APWM input and

direction controlled via the Serial I/O. It features current limit

and thermal shutdown protection.

BOOST VOLTAGE (VBOOST)

This is the boost voltage storage node for the charge pump

circuit. It provides the gate drive voltage for the high-side

FETS in the DC motor drivers, switch mode controllers, and

Gateout pin.

SWTICHING CAPACITOR (CP1 AND CP2)

These are the connections for the charge pump flying

capacitor.

HIGH-SIDE MOSFET GATE DRIVER (GATEOUT)

The output terminal for an external N-channel high-side

driver. Enabled via the Serial I/O, it provides gate drive

control for an external N-channel MOSFET high-side switch.

DC MOTOR B OUTPUT B (BDCMB)

A high-side and low-side driver output terminal, which

when combined with BDCMB, forms the B H-bridge DC motor

driver. The drivers are PWM controlled via the BPWM input,

and direction controlled via the Serial I/O. It features current

limit and thermal shutdown protection.

DC MOTOR B OUTPUT A (BDCMA)

A high-side and low-side driver output terminal, which

when combined with BDCMA, forms the B H-bridge DC motor

driver. The drivers are PWM controlled via the BPWM input,

and direction controlled via the Serial I/O. It features current

limit and thermal shutdown protection.

5.0 V REGULATOR MODE SELECT (5 V SELECT)

This terminal is used to set the 5v regulator to operate in

either linear or switching mode. Ground this terminal to

operate in switching mode, or float to operate in linear mode.

5.0 V REGULATOR SWITCH OUTPUT (5 V SWITCH)

This terminal is the high-side driver output used for the 5v

switching regulator. It uses the internal 200KHZ clock.

5.0 V REGULATOR INPUT SUPPLY (5 V SUPPLY)

The input voltage terminal for the 5v regulator. Limit it to

20v in linear mode. An additional series resistor is

recommended to dissipate power off-chip.

5.0 V REGULATOR FEEDBACK (5 V)

This is the 5v feedback input terminal and output voltage

point for the 5v regulator when in the switch configuration,

and the output pin when tied to 5v SWITCH in linear

configuration. It is also the power supply terminal for the

MC34921AE on board logic.

AN0/ANALOGOUT_A (AN0/ANALOGOUT_A)

Mux input 0 for the A/D converter, which is also available

in Freescale test mode as an output for the AN2 I/V

converter.

AN1/ANALOGOUT_B (AN1/ANALOGOUT_B)

Mux input 1 for the A/D converter, which is also available

in Freescale test mode as an output for the AN3 I/V

converter.

AN2/ANALOGIN_A (AN2/ANALOGIN_A)

Mux input 2 for the A/D converter incorporating an I/V

converter with offset and gain calibration via the Serial I/O.

AN3/ANALOGIN_B (AN3/ANALOGIN_B)

Mux input 3 for the A/D converter incorporating an I/V

converter with offset and gain calibration via the Serial I/O.

ANALOG ENCODER CHANNEL B FILTER

(ENC_FILTB)

Input to the AN3 I/V converter stage for feedback

components used with the I/V converter op amp.

ANALOG ENCODER CHANNEL A FILTER

(ENC_FILTA)

Input to the AN2 I/V converter stage for feedback

components used with the I/V converter op amp.

RESET (RST)

Supervisory function I/O, incorporating a comparator input

and an open drain output, and typically connected to the RST

of a microprocessor. As an input, RST resets internal

registers to default states, turns step motor outputs off, forces

DC motor drive low-side drives on, and sets MISO to a high

Z state. As an output, RST is set during B+ UVLO, all

regulators UVLO, current limit, and thermal shutdown events.

MASTER IN SLAVE OUT (MISO)

This is the master-in-slave-out terminal; the serial output

port of the Serial I/O, which typically connects to the MISO of

a microprocessor. MISO reports two data frames: NORMAL

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