33389 datasheet(18/49 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33389

FUNCTIONAL DEVICE OPERATION

Voltage Regulator V1

V1 is a 5.0 V, three percent low drop voltage regulator

dedicated to the microcontroller supply. It can deliver up to

100 mA. It is totally protected against short-to-ground

(current limitation) and over temperature. V1 is active in

Normal Request, Normal, and Stand-by modes.

No forward parasitic diode exists from V1 to VBAT. This

means if VBAT voltage drops below V1, high current flowing

from V1 to VBAT will not discharge the capacitor connected to

V1. Its stored energy will only be used to supply the

microcontroller and gives time to save all relevant data.

• Under Voltage Reset—V1 is monitored for under voltage

(power-up, power down) and a reset is provided at RST

output for 1 ms. This ensures proper initialization of the

microcontroller at power-on or after supply is lost.

Furthermore, a flag is set in the Reset Source Register

(RSR) and can be read via the SPI.

• Over Temperature Protection—V1 internal ballast

transistor is monitored for over temperature. Two detection

thresholds are provided. A pre-warning threshold at 145°C

and a shut-off threshold at 175°C. Once the first threshold

is reached, a flag is set in the Over Temperature Status

microcontroller. Once the second threshold is reached, a

flag is set in the OTSR, a maskable interrupt is sent to the

microcontroller and V1 is switched OFF.

Once the junction temperature is back to the pre-warning

threshold, V1 regulator will be automatically switched ON.

Note: Current capability of V1, V2 and V3 depends upon the thermal

management. Over temperature shutdown might be reached and

lead to turn OFF of V1, V2, and V3 for output current below their

maximum current capability.

Voltage Regulator V2

V2 is a 5.0 V low drop voltage regulator dedicated to

peripherals supply. It can deliver up to 200 mA and is

protected against short to ground (current limitation) and over

temperature. V2 is active in Normal mode.

• Under Voltage Detection—V2 is monitored for under

voltage and a flag is set in the Voltage Supply Status

• Over Temperature Protection—V2 internal ballast

transistor is monitored for overtemperature. Two detection

thresholds are provided. A pre-warning threshold at 140°C

and a shut-off threshold at 165°C. Once the first threshold

is reached, a flag is set in the readable OTSR register. A

maskable interrupt can be sent to microcontroller.

Once the second threshold is reached, a flag is set in the

OTSR register, V2 is switched OFF. It can only be switched

on again via the SPI.

Switch V3

V3 is a 10

Ω switch to V

BAT. It can be used to supply

external contacts or relays. A great flexibility is given for the

different possible ways for its control. It is protected against

short to ground (current limitation).

• Over Temperature Protection—V3 output transistor is

monitored for over temperature. Once the threshold is

reached, a flag is set in the VSSR register, V3 is switched

OFF. It will be automatically switched ON once the junction

temperature is back to the pre-warning threshold.

Table 6. V1 Control

Conditions for V1 ON

Conditions for V1 OFF

Normal Request Mode

(at V1 Power ON)

Sleep Mode (via SPI)

Normal Mode (via SPI)

Shut-Off Temperature Threshold

Reached

Stand-by Mode (via SPI)

No VBAT Power Supply

(cold start)

V1 Below Pre-Warning

Temperature Threshold

Emergency Mode

During Rest

—

Table 7. V2 Control

Conditions for V2 ON

Conditions for V2 OFF

Normal Mode (via SPI) and V2

Below Shut-Off Temperature

Threshold

Sleep, Stand-by, Normal

Request, or Emergency Modes

(via SPI)

—

Shut-Off Temperature Threshold

Reached

—

V1 Disabled (for any reason)

Table 8. V3 Control

Conditions For V3 ON

Conditions For V3 OFF

Permanently in Normal Mode

if Configured via SPI

Permanently in Normal

Mode if Configured

Permanently in Stand-by

Mode if Configured via SPI

Normal Request Mode

In Sleep Mode, During

Enable Time of Cyclic

Sense if Configured

Permanently in Stand-by

Mode if Configured

—

Permanently in Sleep

Mode if Configured

33389 Datasheet(PDF) 18 Page - Freescale Semiconductor, Inc

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