Application Circuits

Note:

* The connection of the IRQ and RD pin is selectable depending on the requirement of the MCU.

Adjust R (external pull-high resistance) to fit user

¢s time base clock.

Command Summary

Name

ID

Command Code

D/C

Function

Def.

READ

110

A5A4A3A2A1A0D0D1D2D3

D

Read data from the RAM

WRITE

101

A5A4A3A2A1A0D0D1D2D3

D

Write data to the RAM

READ

MODIFY

WRITE

101

A5A4A3A2A1A0D0D D2D3

D

Read and write to the RAM

SYS DIS

100

0000-0000-X

C

Turn off both system oscillator and LCD

bias generator

Yes

SYS EN

100

0000-0001-X

C

Turn on system oscillator

LCD OFF

100

0000-0010-X

C

Turn off LCD bias generator

Yes

LCD ON

100

0000-0011-X

C

Turn on LCD bias generator

TIMER DIS

100

0000-0100-X

C

Disable time base output

Yes

WDT DIS

100

0000-0101-X

C

Disable WDT time-out flag output

Yes

TIMER EN

100

0000-0110-X

C

Enable time base output

WDT EN

100

0000-0111-X

C

Enable WDT time-out flag output

TONE OFF

100

0000-1000-X

C

Turn off tone outputs

Yes

CLR TIMER

100

0000-1101-X

C

Clear the contents of the time base

generator

CLR WDT

100

0000-111X-X

C

Clear the contents of the WDT stage

BIAS 1/2

100

0010-abX0-X

C

LCD 1/2 bias option

ab=00: 2 commons option

ab=01: 3 commons option

ab=10: 4 commons option

HT1620

Rev. 1.80

13

July 27, 2009

PATENTED

0 . 1 m F

I R Q *

D A T A

C S

R D *

W R

M C U

H T 1 6 2 0

L C D P a n e l

B Z

O S C I

O S C O

B Z

C r y s t a l

3 2 7 6 8 H z

O s c i l l a t o r

C O M 0 ~ C O M 3

S E G 0 ~ S E G 3 1

C C 1

C C 2

V E E

V O 1 5 N

P i e z o

1 / 2 o r 1 / 3 B i a s ; 1 / 2 , 1 / 3 o r 1 / 4 D u t y

R

3 M W

0 . 1 m F

0 . 1 m F