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HT7500 Clinical Thermometer
Features
* * *
*
Single-chip CMOS construction Single 1.5V battery operation Measurement range: +32.0~+42.0C (+90.0~+108.0F) Measurement accuracy: 0.1C (0.2F) Resolution: 0.1C (0.1F) Bonding option for Centigrade/Fahrenheit measurement
* * * * *
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
General Description
The HT7500 is a CMOS digital clinical thermometer IC for measuring body temperature in Centigrade (C) or Fahrenheit (F) mode by its bonding option. It also provides alarm and auto power off functions. The other electronic components are LCD display, thermister, 1.5V battery, ON/OFF switch, buzzer, resistors and capacitors.
Block Diagram
OSCI OSCO TEST2 PSW CLFH RF RS SC VDD VSS
S y s te m OSC
C o u n te r a n d C o m p a ra to r
T IM E R
LO W C BZ1 BZ2 C512 CAP VEE
C o n tro l C ir c u it
V o lta g e D o u b le r C o u n te r , C o m p a ra to r a n d L a tc h
S ensor OSC
P u ls e G e n e ra to r
P u ls e T a b le
LCD
D r iv e r
CO M 1~3 SA1~SD1
TV
T IM
TEST1
TS816
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HT7500
Pad Assignment
TEST1 TS816 33 C512 CAP SD1 VEE SC3 T IM 32 TV 30
31
29
28
27 26
25 24 23 22 21 SC2 SC1 SB3 SB2 SB1 SA3 SA2 SA1
LO W C 1 2 3 4 5 6 VSS SC RF RS VDD PSW
20 (0 ,0 ) 19 18 17
7 8 9 10 OSCI 11 OSCO 12 BZ1 13 BZ2 14 COM1 15 COM2 16 COM3
* The IC substrate should be connected to VDD in the PCB layout artwork.
CLFH TEST2
Chip size: 129 120 (mil)
2
Pad Coordinates
Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 X -58.61 -58.61 -58.61 -58.61 -58.61 -58.61 -58.61 -57.25 -50.62 -43.99 -37.36 -15.64 -3.19 7.44 26.05 58.48 58.82 Y 18.57 6.16 -1.49 -13.30 -20.95 -33.02 -40.08 -53.63 -53.63 -53.63 -53.63 -53.34 -53.34 -52.66 -52.66 -48.75 -7.14 Pin No. 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 X 58.82 58.82 58.82 58.82 58.82 58.82 58.82 46.24 38.59 31.96 24.82 7.39 -0.43 -14.28 -23.63 -42.33
Unit: mil Y 0.51 8.24 15.90 23.63 31.28 39.01 46.67 54.06 54.06 54.06 54.06 54.06 53.29 53.29 53.29 53.29
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Pad Description
Pad No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14~16 17~19 20~22 23~25 26 27 28 29 30 31 32 33 Pad Name LOWC VSS SC RF RS VDD PSW TEST2 CLFH OSCI OSCO BZ1 BZ2 COM1~COM3 SA1~SA3 SB1~SB3 SC1~SC3 SD1 VEE CAP C512 TV TEST1 TIM TS816 I/O B I B O O 3/4 I I I I O O O O O O O O O O O B I I I Power supply GND Common point, NMOS open drain Connect reference resistor, PMOS open drain Connect sensor resistor, PMOS open drain Positive power supply Pull-low input pin, push switch to turn power on or off 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 For system oscillator in For system oscillator out Buzzer output 1 Buzzer output 2 LCD backplane drive, 3-level voltage out LCD segment drive LCD segment drive LCD segment drive LCD segment drive Generate negative voltage (-1.5V) For negative voltage, NMOS output For negative voltage, inverter output Test pin for IC Test pin for IC Test pin for IC Test pin for IC Function For the supply voltage detector, open the pin when not in use.
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Absolute Maximum Ratings
Supply voltage ...................................0V to 2.0V Operation Temperature ...........-2.0C to +75C Input voltage .................VSS-0.5V to VDD+0.5V Storage Temperature ..............-55C to +125C
Note: These are stress ratings only. Stresses exceeding the range specified under Absolute Maximum Ratings may cause substantial damage to the device. Functional operation of this device at other conditions beyond those listed in the specification is not implied and prolonged exposure to extreme conditions may affect device reliability.
Electrical Characteristics
Symbol VDD IDD ISTB fOSC RC RF Parameter Operating Voltage Operating Current Standby Current Oscillating Frequency Temperature Measurement Accuracy at Range 35C~39C Temperature Measurement Accuracy at Range 95F~102F Test Conditions VDD 3/4 1.5V 1.5V 1.5V 3/4 3/4 Conditions 3/4 No load 3/4 ROSC=820kW 3/4 3/4 Min. 1.3 3/4 3/4 25.6 -0.1 -0.2 Typ. 1.5 60 3/4 32 3/4 3/4 Max. 1.65 100 1.0 38.4 0.1 0.2
Ta=25C Unit V mA mA kHz C F
LCD Electrode Pattern
A1 H1 F1 G1 H1 E1 D1 C1 E2 D2 B1 F2 G2 C2 H2 E3 D3 A2 B2 F3 G3 C3 A3 B3 A4 B4 C4 H3
SA1 COM1 COM2 COM3 F1 E1 H1
SA2 A1 G1 D1
SA3 B1 C1 3/4
SB1 F2 E2 3/4
SB2 A2 G2 D2
SB3 B2 C2 H2
SC1 F3 E3 3/4
SC2 A3 G3 D3
SC3 B3 C3 H3
SD1 A4 B4 C4
Note: 1/3 duty, 1/2 bias (LCD uses 3V)
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Function Description
* Power sw: push switch to power on or power
off.
j. It will automatically turn the power off when measurement is over for 8 min 40 sec. k. When measurement is over, but if the temperature rises within 8 min 40 sec, the C (or F) mark will flash again (repeat from step 2-d), and starts to count 8 min 40 sec again. l. When beep sound is on for 4 sec, the temperature is not measured.
* When power off: the standby current 1mA. * The frequency of the buzzer is 5.3kHz * Bonding option C or F * Measurement to 0.1 degree in either C or F * Sensor use 503ET * Reference resistor is the value
* When power on: push the switch, then it will
generate a beep sound for 0.125 sec. a. First displays all the segments on for 2 sec.
b. After a. as described above, then shows the last time measured temperature for 2 sec. c. After b., shows L C or F for 0.75 sec. d. After c., displays the measured temperature, then C or F mark will flash at a speed of 1Hz. e. If the temperature is < 32C (or 90F), the display shows L C (or F). f. If the temperature 42C (or 108F the display shows H C (or F ). g. The display always shows the higher temperature during the temperature measurement. h. If the measured temperature does not change for more than 16 sec., the measurement is over and the C (or F) mark flash stops. i. When measurement is over, if the temperature > 37.5C (or 99.5F) the buzzer alarms beep-beep-beep-beepbeep-beep- for 4 sec, as follows:
BI 0 .1 2 5 S 0 .1 2 5 S BI 0 .1 2 5 S 0 .1 2 5 S BI 0 .1 2 5 S 0 .1 2 5 S 0 .3 7 5 S
(sensor in 37.0C)
* When battery voltage is low, the battery mark
N flashes at the speed of 1Hz and the measurement may not be accurate. The low voltage detect: 1.35V 0.05V. der to adjust the reference resistance (RF), let test 2 be floating, the measured temperature will be the actual temperature of the measured environment. It can be up or down, not always the higher one.
* During the process of mass production, in or-
if the temperature 37.5C (or 99.5F), the buzzer alarms beep-beep-beep-beep- for 4 sec, as follows:
BI 0 .5 S 0 .5 S
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Flow Chart
PowerO n D is p la y A ll S e g m e n t D is p la y L a s t M e a s u r e d T e m p e ra tu re D is p la y L C 2 sec
2 sec
0 .7 5 s e c
M e a s u re
D is p la y LC
D is p la y th e H ig h e s t V a lu e
D is p la y H C
D is p la y N o t C h a n g e d fo r O ver16 sec
No
A la r m
C N o t F la s h fo r 4 s e c ( C a n 't M e a s u r e )
Yes
T e m p e ra tu re R is e s w ith in 8 m in 4 0 s e c No P o w e r O ff
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Application Circuits
0 .0 2 2 m F LO W C VSS SC RF RS VDD PSW TEST2 CLFH OSCI OSCO B uzzer BZ1 BZ2 C5 C V S 12 AP EE D1
400kW 2200~2700pF 1 .5 V B a tte ry REF SENSOR
0 .0 2 2 m F
SC 1~3 SB1~3 SA1~3 COM3 COM2 COM1
To LCD
R
OSC
=820kW
06%#
Note: Substrate connect to VDD VEE, CAP, and C512 are externally connected to capacitors for stabilizing VEE (=-1.5V). BZ1 and BZ2 are connected to an external buzzer to generate sounds. LOWC is connected to an external resistor for adjusting the detector level of a low voltage detector. Open the pin when not in use. OSCI, OSCO are connected to an external resistor, and form an RC oscillator with a built-in capacitor for SYSTEM clock (=32kHz) RS, RF, SC constitute an alternating RC oscillator, which allows one oscillator, namely RS or RF, active at a time. REF (reference resistor) is a resistor value equal to 503ET, sensor is value in 37.0 C or 98.6 F. SENSOR is a 503ET thermistor.
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Holtek Semiconductor Inc. (Headquarters) No.3 Creation Rd. II, Science-based Industrial Park, Hsinchu, Taiwan, R.O.C. Tel: 886-3-563-1999 Fax: 886-3-563-1189 Holtek Semiconductor Inc. (Taipei Office) 5F, No.576, Sec.7 Chung Hsiao E. Rd., Taipei, Taiwan, R.O.C. Tel: 886-2-2782-9635 Fax: 886-2-2782-9636 Fax: 886-2-2782-7128 (International sales hotline) Holtek Semiconductor (Hong Kong) Ltd. RM.711, Tower 2, Cheung Sha Wan Plaza, 833 Cheung Sha Wan Rd., Kowloon, Hong Kong Tel: 852-2-745-8288 Fax: 852-2-742-8657 Copyright O 2000 by HOLTEK SEMICONDUCTOR INC. The information appearing in this Data Sheet is believed to be accurate at the time of publication. However, Holtek assumes no responsibility arising from the use of the specifications described. The applications mentioned herein are used solely for the purpose of illustration and Holtek makes no warranty or representation that such applications will be suitable without further modification, nor recommends the use of its products for application that may present a risk to human life due to malfunction or otherwise. Holtek reserves the right to alter its products without prior notification. For the most up-to-date information, please visit our web site at http://www.holtek.com.tw.
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