AS3685C datasheet(14/22 Pages) AMSCO

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AS3685C

Datasheet

www.austriamicrosystems.com/AS3685

(ptr)

1.1

13 - 21

7.3 Protection Functions

7.3.1 Overtemperature Protection

If the AS3685 junction temperature exceeds TOVTEMP, the current sink will be disabled and the charge pump

forced into 1:1 mode. If the junction temperature drops below TOVTEMP – TOVTEMPHYST, the device enables the

current sink again and the charge pump resumes normal operation.

7.3.1.1 LED Shortcircuit protection

If the LED is shorted (VCP to ILED), then depending on the set current and the resulting high power dissipation

inside the AS3685, the overtemperature protection will trigger. This protects the AS3685 and the system against

damage. If the AS3685 is in off-mode, then shorting of the diode will have no influence on the system.

Note: Do not short VCP to VSS if the supply is not current limited (e.g. by an internal protection inside the

battery), as there is an internal diode between VBAT (anode) and VCP (cathode).

7.3.2 Flash Timeout

The flash duration of a single flash is limited automatically to tFLASHTIMEOUT (applies only for ‘Flash’ mode(s)).

This protects the flash LED against thermal damage.

7.4 Layout Recommendations

To improve the heat dissipation, use a massive ground plane.

Figure 16 – AS3685 DFN10 3x3mm Layout Recommendation

Figure 17 – AS3685 WL-CSP 2x1.5mm Layout Recommendation

AS3685C Arkusz danych(PDF) 14 Page - ams AG