HT7501 datasheet(5/7 Pages) HOLTEK

5 / 7 page

Functional Description

• Power sw: push switch to turn the power on or

off.

• 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 2.8 sec.

c. After b., shows the self-test temperature

(37.00

±0.01°C ) for 1 sec. The °C mark

will flash at a speed of 1Hz.

d. After c., displays the highest measured

temperature, then the

°C mark will flash at

a speed of 1Hz.

e. If the temperature is < 32.00

°C, the display

shows Lo

°C.

f. If the temperature is

≥ 43.00°C, the display

shows Hi

°C.

g. The display always shows the higher

temperature during the temperature

measurement.

h. If the measured temperature does not

change for more than 8 sec, the measure

ment is over and the

°C mark flash stops.

i. When measurement is over, if the

temperature > 37.50

°C the buzzer alarms

“beep-beep-beep---beep-beep-beep---” for 4 sec,

as follows:

if the temperature

≤ 37.50°C, the buzzer

alarms “beep-beep-beep-beep-” for 4 sec, as

follows:

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 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 ≤ 1µA.

• The frequency of the buzzer is 4kHz or 8kHz

by pin option.

• Fever alarm is pin option.

• Measurement to 0.01 degree at °C.

• Sensor use 503ET.

• Reference resistor is the value (sensor in 37.00°C)

• The low battery and “M” flag cannot display

when the temperature shows Hi or Lo.

• When battery voltage is low, the battery mark

“

∇” flashes at a speed of 1Hz and the measure-

ment may not be accurate. The low voltage

detect: 1.35V

± 0.05V.

• During the process of mass production, in or-

der to adjust the reference resistance (RF), let

test 2 be floating, the measured temperature

will be the actual temperature of the meas-

ured environment. It can be up or down, not

always the higher one.

HT7501

8th Feb ’99

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