AK7841 Datasheet, PDF (10/21 Pages) Asahi Kasei Microsystems – Monaural Audio Class-D Amp with Power Booster for PiezoSpeaker

ASAHI KASEI
AKM CONFIDENTIAL
[AK7840]
„ Pre AMP
Users can change Pre Gain value by setting PG0, PG1, PG2 pins as following Table.1.
For fixed gain application, these pins should be fixed to either VSS3 or DVDDI.
PG2
“Low”
“Low”
“Low”
“Low”
“High”
“High”
“High”
“High”
PG1
PG0
“Low”
“Low”
“Low”
“High”
“High”
“Low”
“High”
“High”
“Low”
“Low”
“Low”
“High”
“High”
“Low”
“High”
“High”
Table.1 Pre Gain setting
Pre Gain Setting
Value
-3.0 dB
0.0 dB
+3.0 dB
+6.0 dB
+9.0 dB
+12.0 dB
+15.0 dB
+18.0 dB
„ Class-D amplifier.
The AK7841, a monaural Class-D audio amplifier, has higher efficiency compared to Class-AB amplifier. AK7841
would eliminate much external equipment especially output filter, which is normally equipped to cut high frequency
spectrum in class-D output, by using a unique circuit composition.
„ Pop Noise Suppressor
The AK7841 features click-and-pop suppression circuit.
„ Power Booster
Built-in BOOST DCDC CONVERTER generates adequate high voltage for Piezo-Speaker (Typ.8.75V) from a
Li-Ion battery voltage range (2.7～4.5V). Supply boosted voltage (VFB=8.75V) to VDD1 for class-D amp operation.
„ Protection
The AK7841 supports following protection circuits for protecting against any damages.
Output Short-Circuit Protection
In case detecting VCL(R)P and VCL(R)N short, the AK7841 clamps peak current of Class-D output circuit
without shutting down the outputs.
Over-Temperature Protection
The AK7841 operation will stop at +150°C.
Note that the AK7841 DOES NOT support resume function from Over-Temperature Protection. Once it is
activated, the AK7841 does not back in normal operation unless “PDN” is toggled (“L” Æ “H”).
Over-Current Protection
Current-limiting protection clamps the output current without shutting down the outputs.
Over-Voltage Protection
AK7841 has a Voltage-limiting protection in DCDC converter to avoid destroying itself.
Rev.08
- 10 -
2008/3