Holtek Semiconductor Inc HT7500 Datasheet

Features

Single-chip CMOS construction

·

Single 1.5V battery operation

·

Measurement range: +32.0~+42.0°C

·

(+90.0~+108.0°F)
Measurement accuracy: ±0.1°C(±0.2°F)
Resolution: 0.1°C (0.1°F)
Bonding option for Centigrade/Fahrenheit

·

measurement

General Description

The HT7500 is a CMOS digital clinical ther
mometer IC for measuring body temperature in
Centigrade (°C) or Fahrenheit (°F) mode by its
bonding option. It also provides alarm and auto

Block Diagram

HT7500

Clinical Thermometer

Alarm warning for fever

·

Highest temperature hold

·

Auto power off after 8 min 40 sec

·

One-key input switch for ON/OFF

·

Displays last time measured temperature

·

power off functions. The other electronic com

­ponents are LCD display, thermister, 1.5V bat
tery, ON/OFF switch, buzzer, resistors and
capacitors.

-

-

OSCI

OSCO

TEST2

PSW

CLFH

RF

RS

SC

VDD

VSS

S ystem

OSC

C ontrol

Circuit

Sensor

OSC

TV

TEST1

C ounter and

C om parator

Pulse

G enerator

Pulse
Table

TIM

TS 816

1 August 8, 2000

TIM ER

Voltage
D oubler

C ounter ,

C om parator and

Latch

LCD Driver

LOW C
BZ1
BZ2

C 512
CAP
VEE

COM 1~3
SA1~SD1

HT7500

Pad Assignment

* The IC substrate should be connected to VDD in the PCB layout artwork.

L O W C

VSS

VDD

PSW

SC

RF

RS

TS 816

33

1

2

3

4

5

6

7

8

10

9

TEST2

CLFH

OSCI

OSCO

Chip size: 129 ´ 120 (mil)

TEST1

TIM

32

31

12

BZ1

C 512

CAP

VEE

SC3

TV

29

30

(0 ,0 )

14

13

BZ2

COM 1

SD1

25

26

271128

24

SC2

23

SC1

22

SB3

21

SB2

20

SB1

19

SA3

18

SA2

17

SA1

15

COM 2

2

16

COM 3

Pad Coordinates Unit: mil

Pin No. X Y Pin No. X Y

1
2
3
4
5
6
7
8

9
10
11
12
13

-58.61

-58.61

-58.61 -1.49

-58.61 -13.30

-58.61 -20.95

-58.61 -33.02

-58.61 -40.08

-57.25 -53.63

-50.62 -53.63

-43.99 -53.63

-37.36 -53.63

-15.64 -53.34

-3.19 -53.34

14 7.44
15 26.05
16 58.48
17 58.82

18.57 18 58.82 0.51

6.16 19 58.82 8.24
20 58.82 15.90
21 58.82 23.63
22 58.82 31.28
23 58.82 39.01
24 58.82 46.67
25 46.24 54.06
26 38.59 54.06
27 31.96 54.06
28 24.82 54.06
29 7.39 54.06

-52.66

-52.66

-48.75

30
31
32
33

-0.43

-14.28

-23.63

-42.33

53.29

53.29

53.29

53.29

-7.14

2 August 8, 2000

HT7500

Pad Description

Pad No. Pad Name I/O Function

1 LOWC B For the supply voltage detector, open the pin when not in use.

2 VSS I Power supply GND

3 SC B Common point, NMOS open drain

4 RF O Connect reference resistor, PMOS open drain

5 RS O Connect sensor resistor, PMOS open drain

6 VDD

7 PSW I Pull-low input pin, push switch to turn power on or off

8 TEST2 I

9 CLFH I

10 OSCI I For system oscillator in

11 OSCO O For system oscillator out

12 BZ1 O Buzzer output 1

13 BZ2 O Buzzer output 2

14~16 COM1~COM3 O LCD backplane drive, 3-level voltage out

17~19 SA1~SA3 O LCD segment drive

20~22 SB1~SB3 O LCD segment drive

23~25 SC1~SC3 O LCD segment drive

26 SD1 O LCD segment drive

27 VEE O

28 CAP O For negative voltage, NMOS output

29 C512 O For negative voltage, inverter output

30 TV B Test pin for IC

31 TEST1 I Test pin for IC

32 TIM

33 TS816 I Test pin for IC

Positive power supply

¾

Pull-low test pin, for production test, floating LCD displays
the real time value, when connected to VDD, LCD displays
the highest value.

Floating for °C, connect to VDD for °F

Generate negative voltage (-1.5V)

I Test pin for IC

3 August 8, 2000