Datasheet

FS98O22
Rev. 1.6 36/146
4.3. Analog Bias Circuit
Figure 4-4 analog bias circuit
Analog Bias Circuit is used to activate VB (reference VDDA) as the power supply voltage for analog circuit
(include ADC, OPAMP, Low Battery Comparator) and LCD driver. The Control register flag is ENVB. Please
see Figure 4-4.
Table 4-5 analog bias circuit register table
Address Name
Referenced
Section
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Value on
Power on
Reset
1DH NETF 4/10/11 ENBAND ENVDDA ENAGND ENVB 00000000
Operation:
1. Operate as Section 4.1 to get the VGG (2 times of VDD or external Power Supply).
2. Operate as Section 4.2 to get the VDDA (3.6V).
3. Set the ENVB flag. The VB will be 3.6V (same as VDDA) and the analog function network and the LCD
driver can be activate correctly.
4. Note that Pin VB must be connected with a 10nF capacitor to VSS for reducing Voltage Doubler noise.
FORTUNE'
Properties
For Reference Only