AS3435 datasheet(49/102 Pages) AMSCO

49 / 102 page

ams Datasheet, Confidential: 2014-Jun-13 [v1-30]

AS3415/AS3435 – 49

Detaile d Desc rip t ion

VNEG Charge Pump

The VNEG charge pump uses one external 1μF ceramic capacitor

(CFLY) to generate a negative supply voltage out of the battery

input voltage to supply all audio related blocks. This allows a

true-ground headphone output with no more need of external

DC-decoupling capacitors.

Figure 63:

VNEG Charge Pump

VNEG Charge Pump: This figure shows the block diagram of the VNEG charge pump that supplies all audio blocks

of the AS3415/35.

The charge pump typically requires an additional input

capacitor, CVBAT of 10μF and output capacitor, CVNEG, with the

same size as the input capacitor. The flying capacitor, CFLY,

should be 1μF. If hybrid operation is desired, which means two

ANC chips are working in parallel, it is possible to disable the

VNEG charge pump and share one charge pump for both chips.

This should help to reduce the system power consumption of

the headset.

Parameter

VBAT=1.5V, TA= 25ºC, unless otherwise specified.

Figure 64:

VNEG Charge Pump Parameter

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

VIN

Input voltage

VBAT

1.0

1.5

1.8

VOUT

Output voltage

VNEG

-0.7

-1.5

-1.8

CFLY

External flying capacitor

μF

CVBAT

VBAT input capacitor

μF

CVNEG

VNEG output capacitor

μF

AS3435 Datenblatt(PDF) 49 Page - ams AG

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