AS3525 datasheet(164/194 Pages) AMSCO

164 / 194 page

AS3525-A/-B C22O22

Data Sheet, Confidential

www.austriamicrosystems.com

Revision 1.13

164

- 194

7.4.20

10-Bit ADC

7.4.20.1 General

This general purpose ADC can be used for measuring several voltages and currents to perform functions like battery monitor, temperature

supervision, button press detection, etc.. . Please note that C21O20 is measuring BVDD instead of CHG_OUT

7.4.20.2 Input Sources

Table 152 ADC10 Input Sources

Nr.

Source

Range

LSB

Description

CHG_OUT

5.120V

5mV

check battery voltage of 4V LiIo accumulator

RTCSUP

5.120V

5mV

check RTC backup battery voltage (connected to BVDD inside the

package)

VBUS

5.120V

5mV

check USB host voltage

CHG_IN

5.120V

5mV

check charger input voltage

CVDD

2.560V

2.5mV check charge pump output voltage

BatTemp

2.560V

2.5mV check battery charging temperature

MicSup1

2.560V

2.5mV check voltage on MicSup1 for remote control or external voltage

measurement

MicSup2

2.560V

2.5mV check voltage on MicSup2 for remote control or external voltage

measurement

VBE1

1.024

1mV

measuring junction temperature

VBE2

1.024

1mV

measuring junction temperature

I_MicSup1

1.024mA typ.

1.0uA check current of MicSup1 for remote control detection

I_MicSup2

1.024mA typ.

1.0uA check current of MicSup2 for remote control detection

VBAT

2.560V

2.5mV check single cell battery voltage

13..15

Reserved

1.024V

1mV

for testing purpose only

CHG_OUT, RTCSUP, VBUS, CHG_IN

These sources are fed into an 1/5 voltage divider (180k

Ω typ.) and further amplified by 2.5.

CVDD, BatTemp, MicSup1, MicSup2

These sources are fed directly to the ADC input multiplexer.

VBE1, VBE2

These inputs are first amplified by 2.5 and than fed to the ADC input multiplexer.

I_MicSup1, I_MicSup2

The measurement of the microphone supply LDOs is not very accurate, as the current-voltage conversion is only done by a single resistor which

shows wide process and temperature variations. These measurements should be only used for remote function detection.

VBAT

This source is divided by 2.5 with a voltage divider (180k

Ω typ.) and than amplified by 2.5. This has to be done, as VBAT can represent voltages up

to 3.6V. Please note, that the maximum measurement rage will be still 2.560V

7.4.20.3 Reference

AVDD=2.9V is used as reference to the ADC. AVDD is trimmed to +/-20mV with over all precision of +/-29mV. So the absolute accuracy is +/-1%.

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