ak4650 AKM Semiconductor, Inc., ak4650 Datasheet - Page 45

• Manufacturer Part Number: ak4650
• Description: 16bit 6 Codec With Mic/hp/spk-amp & Tsc
• Manufacturer: AKM Semiconductor, Inc.

L
The AK4650 incorporates a 12-bit successive approximation resistor A/D converter for position measurement, and
battery voltage. The architecture is based on capacitive redistribution algorithm, and an internal capacitor array functions
as the sample/hold circuit.
The A/D converter output is a straight binary format as shown in Table 40:
The A/D converter’s full scale measurements depend on the input mode.
L
Analog input is selected via the A2-0 and SER bits in the control register. If the analog inputs are the X or Y-axis and the
SER bit is set to “0”(differential mode), the full scale ( VREF) is the differential voltage between the non-inverting
terminal and the inverting terminal of the measured axis (e.g. (XP) – (XN)). Analog non-inverting input to A/D converter
( AIN) is the non-inverting terminal of the non-measured axis while the inverting input is the inverting terminal of the
measured axis. If the SER bit is set to “1” (single-ended mode), the full scale of A/D converter ( VREF) is the internal
reference voltage, or external reference voltage. Note that the SER bit should be set to “0” if the IN2 pin is selected as
analog input; nevertheless, the IN2 pin is actually measured by single-ended mode.
MS0502-E-01
A/D Converter for Touch Screen
Analog Inputs
SER bit
0
1
Analog Input Type
Single-ended
Differential
( VREF 1.5LSB)
( VREF 2.5LSB)
Table 41. Analog Input Type, VREF and AIN
0.5LSB
Input Voltage
X-axis measurement: XP
Y-axis measurement: YP
0
VREF: (VREF+) – (VREF )
Table 40. Output Code
:
~
~
~
~
VREF
( VREF 1.5LSB)
1.5LSB
0.5LSB
VREF
- 45 -
VREF
TSVSS
XN
YN
Output Code
FFEH
FFFH
X-axis measurement: YP
Y-axis measurement: XP
001H
000H
:
AIN
AIN
TSVSS
[AK4650]
XN
YN
2007/04