FS98O21 datasheet(37/136 Pages) FORTUNE

37 / 136 page

FS98O21

Rev. 1.7

37/136

Low Battery Comparator

Figure 4-6 low battery comparator function block

Low Battery Comparator is used for VDD low voltage detection. FS98O21 embeds a voltage divider which can

generate 1/2 VDD and the 1/3 VDD. A multiplexer is used to connect the voltage divides to component input.

The multiplexer’s output is compares with 1.2V. The Control register flags are SILB[1:0] and the ENLB. The

Output flag is LBOUT which is for read only. Please see Figure 4-6.

Table 4-7 low battery comparator register table

Operation:

Operate as Section 4.1 to get the VGG (2 times VDD or external Power Supply).

Operate as Section 4.2 to get the VDDA (3.6V)

Operate as Section 4.3 to active the Analog Bias Circuit

Set SILB to choose the Comparator input. Please see Table 4-8

Table 4-8 low battery comparator voltage detection selection table

SILB [1:0]

Detection Voltage

if LBOUT = 1

1/2 VDD

VDD > 2.3 volt

1/3 VDD

VDD > 3.5 volt

AIN

AIN > 1.2 volt

Set the ENLB register flag, and the Low Battery Comparator is enabled.

The output, LBOUT, is the result of the comparator.

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

1Ch

NETE

4/10/11

ENVS SILB[1:0] ENLB

00000000

1Fh

SVD

4.5

LBOUT

uuuuuuuu

MUX

ENLB

1.2V

1/2 VDD

1/3 VDD

SILB[1:0]

AIN4

LBOUT

FS98O21 Datasheet(PDF) 37 Page - Fortune Semiconductor Corp.

FS98O21 Datasheet(HTML) 37 Page - Fortune Semiconductor Corp.

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL