DN1220 データシートの表示（PDF） - Unspecified
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コンポーネント説明
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DN1220 Datasheet PDF : 9 Pages
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DN1220
Setting Up The DN1220 TEC Controller
Jumper
disables
integrator
RTC
RG
Temperature
Set Resistor
RS
NTC
Thermistor
RT
7
6 100 KΩ
5
4 5 KΩ
3 VR =
3.0 Volts
2 +1
1
1 µF
VR
2
∑
1 MΩ
8
VR
2
= 1.5 Volts
VR 9
2
10
VR
VR
2 11
12
RCL1
RCL2
22µF
20VDC
++
Supply Voltage
5 to 12 Volts D.C.
VOLTAGE TO
CURRENT
POWER STAGE
IN VOLTAGE OUT
LIMITER
- 1 13
14
COOL
Thermoelectric
TEC Cooler (TEC)
Figure 2
Setting the Temperature of the TEC
The DN1220 is designed to operate with a Negative Temperature Coefficent (NTC) thermistor that senses the
temperature of the thermoelectric cooler (TEC). The thermistor RT is connected between Pin 1 and Pin 2 as
illustrated in Figure 2. The temperature set reisistor RS is connected between Pin 2 and Pin 3.
To set the temperature of the TEC, follow 3 simple steps:
1. Determine the operating temperature of the TEC.
2. Find the resistive value for the thermistor at this temperature from a "look-up" table.
3. Select a temperature set resistor (Rs) that is the same value.
(The control loop forces the temperature of the TEC so that RT is equal to RS)
Example:
• The desired operating temperature for the TEC is 15°C.
• The thermistor (RT) used, is a Betatherm 10 KΩ model 10K3A2 that has a value of 15.7 KΩ at 15°C.
• The temperature set resistor of 15.8 KΩ is selected because it is the nearest 1% resistor value.
• The control loop will force the TEC to 15°C.
The accuracy with which the temperature can be set is dependent on the tolerance of the thermistor used.
Manufacturers of thermistors normally supply devices that have resistance tolerances at 25°C of ±1, ±2, ±5, and
±10% of the specified value. The thermistor used in this example has a negative temperature coefficient of -4.4%
per °C. Therefore, the best temperature set accuracy that can be expected is approximately ±2.5% for a 10%
tolerance thermistor and an accuracy of ±0.5% with a 1% tolerence thermistor.
Proportional Gain
RG sets the proportional gain of the the control loop from 1 to 200. Proportional gain should be set as large as
possible to minimize temperature overshoot. However, if the gain is too large, loop instability will result. It is
recommended that the integrator be disabled when setting the proportional gain. This is done by shorting Pin 6
to Pin 7.
Gain
RG KΩ
RG =
1,000
G
5 KΩ
200
0
50
15
1
1,000
Page 3
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