33903 datasheet(35/104 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33903/4/5

FUNCTIONAL DESCRIPTION

FUNCTIONAL PIN DESCRIPTION

VAUX is controlled via the SPI, and can be turned ON or

OFF. VAUX low threshold detection and over-current

information will disable VAUX, and are reported in the SPI and

can generate INT.

VAUX is OFF by default and must be turned ON by the SPI.

UNDER-VOLTAGE RESET AND RESET FUNCTION

(RST)

The RESET pin is an open drain structure with an internal

pull-up resistor. The LS driver has limited current capability

when asserted low, in order to tolerate a short to 5.0 V. The

RESET pin voltage is monitored in order to detect failure (e.g.

RESET pin shorted to 5.0 V or GND).

The RESET pin reports an under-voltage condition to the

MCU at the VDD pin, as well as failure in the watchdog

refresh operation. VDD under-voltage reset also operates in

LP VDD ON Mode.

Two VDD under-voltage thresholds are included. The

upper (typically 4.65 V, RST-TH1-5) can lead to a Reset or an

Interrupt. This is selected by the SPI. When “RST-TH2-5“is

selected, in Normal Mode, an INT is asserted when VDD falls

below “RST-TH1-5“, then, when VDD falls below “RST-TH2-5” a

Reset will occur. This will allow the MCU to operate in a

degraded mode (i.e., with 4.0 V VDD).

I/O PINS (I/O-0: I/O-3)

I/Os are configurable input/output pins. They can be used

for small loads or to drive external transistors. When used as

output drivers, the I/Os are either a HS or LS type. They can

also be set to high-impedance. I/Os are controlled by the SPI

and at power on, the I/Os are set as inputs. They include

over-load protection by temperature or excess of a voltage

drop.

When I/O-0/-1/-2/-3 voltage is greater than VSUP/2

voltage, the leakage current (II/O_LEAK) parameter is not

applicable

• I/O-0 and I/O-1 will have current flowing into the device

through three diodes limited by an 80 kOhm resistor (in

series).

• I/O-2 and I/O-3 will have unlimited current flowing into the

device through one diode.

In LP Mode, the state of the I/O can be turned ON or OFF,

with extremely low power consumption (except when there is

a load). Protection is disabled in LP Mode.

When cyclic sense is used, I/O-0 is the HS/LS switch, I/O-

1, -2 and -3 are the wake inputs.

I/O-2 and I/O-3 pins share the LIN Master pin function.

VSENSE INPUT (VSENSE)

This pin can be connected to the battery line (before the

reverse battery protection diode), via a serial resistor and a

capacitor to GND. It incorporates a threshold detector to

sense the battery voltage and provide a battery early

warning. It also includes a resistor divider to measure the

VSENSE voltage via the MUX-OUT pin.

MUX-OUTPUT (MUXOUT)

The MUX-OUT pin (Figure 24) delivers an analog voltage

to the MCU A/D input. The voltage to be delivered to MUX-

OUT is selected via the SPI, from one of the following

functions: VSUP/1, VSENSE, I/O-0, I/O-1, Internal 2.5 V

reference, die temperature sensor, VDD current copy.

Voltage divider or amplifier is inserted in the chain, as

shown in Figure 24.

For the VDD current copy, a resistor must be added to the

MUX-OUT pin, to convert current into voltage. Device

includes an internal 2.0 k resistor selectable by the SPI.

Voltage range at MUX-OUT is from GND to VDD. It is

automatically limited to VDD (max 3.3 V for 3.3 V part

numbers).

The MUX-OUT buffer is supplied from 5 V-CAN regulator,

so the 5 V-CAN regulator must be ON in order to have:

1) MUX-OUT functionality and

2) SPI selection of the analog function.

If the 5 V-CAN is OFF, the MUX-OUT voltage is near GND

and the SPI command that selects one of the analog inputs

is ignored.

Delay must be respected between SPI commands for 5 V-

CAN turned ON and SPI to select MUX-OUT function. The

delay depends mainly upon the 5 V-CAN capacitor and load

on 5 V-CAN.

The delay can be estimated using the following formula:

delay = C(5 V-CAN) x U (5.0 V) / I_lim 5 V-CAN.

C = cap at 5 V-CAN regulator, U = 5.0 V,

I_LIM 5 V-CAN = min current limit of 5 V-CAN regulator

(parameter 5 V-C ILIM).

33903 Datasheet(PDF) 35 Page - Freescale Semiconductor, Inc

33903 Datasheet(HTML) 35 Page - Freescale Semiconductor, Inc

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