AS3687 datasheet(44/55 Pages) AMSCO

44 / 55 page

AS3687/87XM

Datasheet

www.austriamicrosystems.com/AS3687

1v3-4

43 - 54

Table

16 – Reset Levels

Symbol

Parameter

Min

Typ

Max

Unit

Note

VPOR_VBAT

Overall Power-On

Reset

1.8

2.15

2.4

Monitor voltage on V2_5; power-on

reset for all internal functions.

VPOR_PERI

Reset Level for pins

SCL, SDA

0.29

1.0

1.38

Monitor voltage on pins SCL, SDA

tPOR_DEB

Reset debounce time

for pins SCL, SDA

100

120

tSTART

Interface Startup Time

7.7.1 Reset control register

Addr: 29h

Overtemp Control

This register reads and resets the overtemperature flag.

Bit

Bit Name

Default

Access

Description

shutdwn_enab

R/W

Enable Shutdown mode and serial interface reset.

0 Serial Interface reset disabled. Device does not enter

Shutdown mode

1 Serial Interface reset enabled, device enters shutdown

when SCL and SDA remain low for min. 120ms

7.8

Temperature Supervision

An integrated temperature sensor provides over-temperature protection for the AS3687/87XM. This sensor

generates a flag if the device temperature reaches the overtemperature threshold of 140º. The threshold has a

hysteresis to prevent oscillation effects.

If the device temperature exceeds the 140º threshold all current sources, the charge pump and the dcdc

converter is disabled and the ov_temp flag is set. After decreasing the temperature by 5º (typically) operation is

resumed.

The ov_temp flag can only be reset by first writing a 1 and then a 0 to the bit rst_ov_temp.

Bit ov_temp_on = 1 activates temperature supervision.

Table

17 – Overtemperature Detection

Symbol

Parameter

Min

Typ

Max

Unit

Note

T140

ov_temp Rising Threshold

140

º C

Thyst

ov_temp Hystersis

º C

2 Guaranteed by design – not production tested.

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