AS3668_07 datasheet(21/59 Pages) AMSCO

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AS3668

Data Sheet - Detailed Description

Figure 26. VBAT Monitor Block Diagram

8.4.1 VBAT Monitor Registers .

8.5 Temperature Supervision

An integrated temperature sensor provides over-temperature protection for the AS3668. This sensor generates a flag if the device temperature

reaches the over temperature threshold of 140º. The threshold has a hysteresis to prevent oscillation effects.

If the device temperature exceeds the T140 threshold all current sources and the charge pump get disabled and the ov_temp flag is set. After

decreasing the temperature by THYST operation is resumed. Although the device resumes ordinary operation after a overtemperature event, the

register ov_temp keeps set to 1. Even a read operation from the register doesn’t reset the register. Therefore it’s necessary to use the register

rst_ov_temp to reset the overtemperature register ov_temp.

Table 18. VBAT Monitor Parameters

Symbol

Parameter

Condition

Min

Typ

Max

Unit

VMON_VBAT

mode voltage

depending on register setting the voltage can be

configured

3.0V

3.3V

Table 19. Overtemperature Control / VBAT Monitor Register

0x29 Overtemperature Control / VBAT Monitor Register

Bit

Bit Name

Default

Access

Bit Description

6:5

vmon_vbat

R/W

0: Device enters shutdown mode if VBAT voltage drops below ~2.0V

1: Device enters standby mode if VBAT voltage drops below 3.0V

2: Device enters standby mode if VBAT voltage drops below 3.15V

3:Device enters standby mode if VBAT voltage drops below 3.3V

shutdown_enable

R/W

This bit allows the user to disable the I2C shutdown feature. If the bit is set to

‘0’ both I2C signal lines can be low without shutting down AS3668.

0: disables the automatic shutdown of AS3668

1: enables the automatic shutdown of AS3668

rst_ov_temp

This register is a self clearing register. Write a ‘1’ to this register to clear

ov_temp.

ov_temp

This is a read only register and provides feedback about the junction

temperature of the chip. The bit is usually set if the junction temperature

reaches about 140°C.

0: Junction temperature OK

1: Junction Overtemperature

ov_temp_on

R/W

This bit allows the user the enable/disable the junction temperature

monitoring for AS3668.

0: Temperature supervision OFF

1: Temperature supervision ON

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