33800 datasheet(17/39 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33800

FUNCTIONAL DESCRIPTION

FUNCTIONAL PIN DESCRIPTION

Power On Reset (POR). All internal registers will be placed in

the reset state. The device has an Internal 100 k

Ω resistor

pull down on the ENABLE pin.

PULSE WIDTH MODULATION (PWM)

The PWM pins are control input pins for the MOSFET pre-

drivers. The PWM pins provide parallel control and can be

programmed for an OR function with the SPI bit or an AND

function with the SPI bit (See Table 12, on page 25 for SPI

message detail). Each PWM input pin has an internal 15µA

pull down current source. The current sources are active

when the device is in Normal Mode.

DRAIN VOLTAGE SENSE (VDSNSX)

The VDSNSx pin has multiple functions for control and

diagnostics of the external MOSFET:

1. By monitoring the drain voltage of the external device,

short circuits and open circuits are detected. The filter

timer and threshold voltage are easily programmed

through SPI (see Table 10, on page 23 and Table 11,

on page 24 for SPI messages).

2. The VDSNSx pins are use to determine the external

load resistance. Further information is provided in the

Device Operation section of this specification.

3. The VDSNSx pins provide a drain to gate clamp for

fast turn off of inductive loads and MOSFET protection.

GATE DRIVER OUTPUTS (GDX)

The GDX pins are the gate drive outputs for an external

MOSFETS. Internal to the device is a Gate to Source resistor

designed to hold the external MOSFET in the OFF state while

the device is in POR.

INPUTS (P1, P3, P5, P7)

The input pins for octal serial switch outputs 1,3,5,7. Each

input control pin has an internal pull down current source.

Two outputs may be controlled in parallel using the PX pins

(See Functional Device Operation on page 25).

VOLTAGE CALIBRATED INPUT (VCAL)

The Voltage calibrated input (VCAL) provides the IC with

a reference voltage for analog circuits. VCAL (EXT or INT)

must be applied for the CCD1 and CCD2 constant current

controllers and Load Resistance measurement function to

operate. For applications where measurements are not

critical, the VCAL pin may grounded and an internally

generated reference will be used. Using the internally

generated reference will add

±10% to all tolerances in the

parametric table.

LOAD RESISTANCE FEEDBACK (LRFDBK)

The LRFDBK pin is an operational amplifier output. The

amplifier output voltage is proportional to the load resistance

for the selected channel. The channel is selected via the SPI.

DEFAULT

The DEFAULT input controls the operation of each driver

to a Default Mode. The DEFAULT input must be logic 0 for full

function of all output drivers. For more information on the

DEFAULT operation (See Functional Device Operation on

page 19).

With the DEFAULT pin HIGH, the device is placed in

Default Mode. The DEFAULT pin is pulled up to the VDD

supply through an active pull up current source. In Default

Mode the device operates in the following manner:

1. OSS outputs are disabled.

2. CCD1 and CCD2 outputs are disabled.

3. SPI ON/OFF control of GATE DRIVE (GD1 to GD6)

outputs and on board PWM controllers are disabled. PWMx

input control is enabled.

In the Default Mode the device retains all register

information and output status information. Normal operation

will resume when the DEFAULT pin transitions low again and

the device will operate as programmed prior to Default Mode.

RESISTOR EXTERNAL REFERENCE (REXT)

The reference current is used in the equation to calculate

the load resistance of the PWM outputs. The load resistance

measurement current is inversely proportional to REXT

current. The resistor value may be changed to adjust the load

measurement current. A 24

Ω resistor to ground sets the

LRFDBK output to 260mV/

Ω.

EXPOSED PAD

The silicon die is epoxy attached to the top side of the pad.

Although the device does not use the pad for electrical

conduction, the bottom side exposed pad of the package

should be grounded.

33800 Datasheet(PDF) 17 Page - Freescale Semiconductor, Inc

33800 Datasheet(HTML) 17 Page - Freescale Semiconductor, Inc

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