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参数资料
| 型号： | MAX1979ETM |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | 温度/湿度传感器 |
| 英文描述： | Integrated Temperature Controllers for Peltier Modules |
| 中文描述： | DIGITAL TEMP SENSOR-SERIAL, 1Cel, SQUARE, SURFACE MOUNT |
| 封装： | EXPOSED PAD, TQFP-48 |
| 文件页数： | 17/20页 |
| 文件大小： | 620K |
| 代理商： | MAX1979ETM |
Shutdown Control
Drive
SHDN
low to place the MAX1978/MAX1979 in a
power-saving shutdown mode. When the MAX1978/
MAX1979 are in shutdown, the TEC is off (V
OS1
and
V
OS2
decay to GND) and input supply current lowers to
2mA (typ).
ITEC Output
ITEC is a status output that provides a voltage propor-
tional to the actual TEC current. ITEC = REF when TEC
current is zero. The transfer function for the ITEC output:
V
ITEC
= 1.50 + 8
(V
OS1
- V
CS
)
Use ITEC to monitor the cooling or heating current
through the TEC. The maximum capacitance that ITEC
can drive is 100pF.
Applications Information
The MAX1978/MAX1979 drive a thermoelectric cooler
inside a thermal-control loop. TEC drive polarity and
power are regulated to maintain a stable control tem-
perature based on temperature information read from a
thermistor, or from other temperature-measuring
devices. Carefully selected external components can
achieve 0.001
°
C temperature stability. The MAX1978/
MAX1979 provide precision amplifiers and an integra-
tor amplifier to implement the thermal-control loop
(Figures 1 and 2).
Connecting and Compensating the
Thermal-Control Loop
Typically, the thermal loop consists of an error amplifier
and proportional integral derivative controller (PID)
(Figure 4). The thermal response of the TEC module
must be understood before compensating the thermal
loop. In particular, TECs generally have stronger heat-
ing capacity than cooling capacity because of the
effects of waste heat. Consider this point when analyz-
ing the TEC response.
Analysis of the TEC using a signal analyzer can ease
compensation calculations. Most TECs can be crudely
modeled as a two-pole system. The second pole poten-
tially creates an oscillatory condition because of the
associated 180
°
phase shift. A dominant pole compen-
sation scheme is not practical because the crossover
frequency (the point of the Bode plot where the gain is
zero dB) must be below the TEC
’
s first pole, often as
low as 0.02Hz. This requires an excessively large inte-
grator capacitor and results in slow loop-transient
response. A better approach is to use a PID controller,
where two additional zeros are used to cancel the TEC
and integrator poles. Adequate phase margin can be
achieved near the frequency of the TEC
’
s second pole
when using a PID controller. The following is an exam-
ple of the compensation procedure using a PID con-
troller.
Figure 6 details a two-pole transfer function of a typical
TEC module. This Bode plot can be generated with a
signal analyzer driving the CTLI input of the
MAX1978/MAX1979, while plotting the thermistor volt-
age from the module. For the example module, the two
poles are at 0.02Hz and 1Hz.
The first step in compensating the control loop involves
selecting components R3 and C2 for highest DC gain.
Film capacitors provide the lowest leakage but can be
large. Ceramic capacitors are a good compromise
between low leakage and small size. Tantalum and
electrolytic capacitors have the highest leakage and
generally are not suitable for this application. The inte-
grating capacitor, C2, and R3 (Figure 4) set the first
zero (fz1). The specific application dictates where the
first zero should be set. Choosing a very low frequency
results in a very large value capacitor. Set the first zero
frequency to no more than 8 times the frequency of the
lowest TEC pole. Setting the frequency more than 8
times the lowest pole results in the phase falling below
-135
°
and may cause instability in the system. For this
example, C2 = 10μF. Resistor R3 then sets the zero at
0.16Hz using the following equation:
This yields a value of R3 = 99.47k
. For our example,
use 100k
.
Next, adjust the gain for a crossover frequency for max-
imum phase margin near the TEC
’
s second pole. From
Figure 6, the TEC bode plot, approximately 30dB of
gain is needed to move the 0dB crossover point up to
1.5Hz. The error amplifier provides a fixed gain of 50,
or approximately 34dB. Therefore, the integrator needs
to provide -4dB of gain at 1.5Hz. C1 and R3 set the
gain at the crossover frequency.
C
A
C
R
f
C
1
1
2
2
3
=
+
×
×
π
fz
C
R
1
1
2
2
3
=
×
×
π
M
Integrated Temperature
Controllers for Peltier Modules
______________________________________________________________________________________
17
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1979ETM+ | 功能描述:电压模式 PWM 控制器 Integrated Temp Ctlr for Peltier Modules RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX1979ETM+T | 功能描述:电压模式 PWM 控制器 Integrated Temp Ctlr for Peltier Modules RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX1979ETM-T | 功能描述:电压模式 PWM 控制器 RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX197ACAI | 功能描述:模数转换器 - ADC Integrated Circuits (ICs) RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX197ACAI+ | 功能描述:模数转换器 - ADC 12-Bit 8Ch 100ksps 4.18V Precision ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
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