HT7501
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.
5
8th Feb ’99