PC33889

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PC33889

DEVICE DESCRIPTION

4

DEVICE DESCRIPTION

Introduction:

The MC33889 is an integrated circuit dedicated to automotive applications. It includes the following functions:

- One full protected voltage regulator with 200mA total output current capability.

- Driver for external path transistor for V2 regulator function.

- Reset, programmable watchdog function

- Four operational modes

- Wake up capabilities: Forced wake up, cyclic sense and wake up inputs, CAN and SPI

- Can low speed fault tolerant physical interface, compatible with Motorola MC33388D.

4.1

Device Supply

The device is supplied from the battery line through the Vsup pin. An external diode is required to protect against negative

transients and reverse battery. It can operate from 4.5V and under the jump start condition at 27V DC. This pin sustains standard

automotive voltage conditions such as load dump at 40V. When Vsup falls below 3V typical the MC33889 detects it and store the

information into the SPI register, in a bit called “BATFAIL”. This detection is available in all operation modes.

4.2

Vdd1 Voltage Regulator

Vdd1 Regulator is a 5V output voltage with total current capability of 200mA. It includes a voltage monitoring circuitry

associated with a reset function. The Vdd1 regulator is fully protected against over current, short-circuit and has over

temperature detection warning flags and shutdown with hysteresis.

4.3

V2 regulator

V2 Regulator circuitry is designed to drive an external path transistor in order to increase output current flexibility. Two pins

are used: V2 and V2 ctrl. Output voltage is 5V and is realized by a tracking function of the Vdd1 regulator. Recommended ballast

transistor is MJD32C. Other transistor might be used, however depending upon PNP gain an external resistor capacitor network

might be connected between emitter and base of PNP. The use of external ballast is optional (refer to simplified typical

application). State of V2 is reported into IOR register (if V2 is below 4.5V typical in case of over load or short circuit).

4.4

HS1 Vbat Switch Output

HS1 output is a 2 ohms typical switch from Vsup pin. It allows the supply of external switches and their associated pull up or

pull down circuitry, in conjunction with the wake up input pins for example. Output current is limited to 200mA and HS1 is

protected against short-circuit and has an over temperature shutdown (reported in IOR register). HS1 output is controlled from

the internal register and SPI. It can be activated at regular intervals in sleep mode thanks to internal timer. It can also be

permanently turned on in normal or stand-by modes to drive external loads such as relays or supply peripheral components. In

case of inductive load drive external clamp circuitry must be added.

4.5

Functional Modes

The device has four modes of operation, stand-by, normal, stop and sleep modes. All modes are controlled by the SPI. An

additional temporary mode called “normal request mode” is automatically accessed by the device (refer to state machine) after

wake up events. Special mode and configuration are possible for software application debug and flash memory programming.

4.5.1

Normal mode:

In this mode both regulators are ON and this corresponds to the normal application operation. All functions are available in

this mode (watchdog, wake up input reading through SPI, HS1 activation, CAN communication). The software watchdog is

running and must be periodically cleared through SPI.

4.5.2

Standby mode:

Only the regulator 1 is ON. Regulator 2 is turned OFF by disabling the V2 ctrl pin. The CAN cell is not available, as powered

from V2, other functions are available: wake up input reading through SPI, HS1 activation. The watchdog is running.

4.5.3

Sleep mode:

Regulators 1 and 2 are OFF. In this mode, the MCU is not powered. In this mode, the device can be awakened internally by

cyclic sense via the wake up inputs pins and HS1 output, from the forced wake function, the CAN physical interface, and SPI

(CSB pin).

4.5.4

Stop mode

Regulator 2 is turned OFF by disabling the V2 ctrl pin. The regulator 1 is activated in a special low power mode which allow to

deliver 2 mA. The objective is to maintain the MCU of the application supplied while it is turned into power saving condition (i.e

stop or wait mode).

Stop mode is entered through SPI. Stop mode is dedicated to power the Microcontroller when it is in low power mode (stop,

pseudo stop, wait etc.). In these mode the MCU supply current is less than 1mA. The MCU can restart its software application

very quickly, without the complete power up and reset sequence.

When the application is in stop mode (both MCU and SBC), the application can wake up from the SBC side (ex cyclic sense,

forced wake up, CAN message, wake up inputs) or the MCU side (key wake up etc.).

When Stop mode is selected by SPI, stop mode becomes active 20us after end of SPI message. The “go to stop” instruction

must be the last instruction executed by the MCU before going to low power mode.

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com