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| 型号： | MAX8520ETP+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 15/18页 |
| 文件大小： | 0K |
| 描述： | IC DRVR PWR TEC 20-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 应用： | 热电冷却器 |
| 电源电压： | 3 V ~ 5.5 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-WQFN 裸露焊盘 |
| 供应商设备封装： | 20-TQFN-EP（5x5） |
| 包装： | 带卷 (TR) |
Smallest TEC Power Drivers for Optical
Modules
Take care not to exceed the positive or negative cur-
rent limit on the TEC. Refer to the manufacturer’s data
sheet for these limits.
Setting Max TEC Voltage
Apply a voltage to the MAXV pin to control the maxi-
mum differential TEC voltage. V MAXV can vary from 0V
to V REF . The voltage across the TEC is four times
V MAXV and can be positive or negative:
|V OS1 - V OS2 | = 4 x V MAXV or V DD , whichever is lower
Set V MAXV with a resistor-divider between REF and
GND using resistors from 10k ? to 100k ? . V MAXV can
vary from 0V to V REF .
Control Inputs/Outputs
Output Current Control
The voltage at CTLI directly sets the TEC current. CTLI
is typically driven from the output of a temperature con-
trol loop. The transfer function relating current through
the TEC (I TEC ) and V CTLI is given by:
I TEC = (V CTLI - V REF )/(10 R SENSE )
where V REF is 1.50V and:
ITEC = (V OS1 - V CS )/R SENSE
CTLI is centered around REF (1.50V). I TEC is zero when
CTLI = 1.50V. When V CTLI > 1.50V the current flow is from
OS2 to OS1. The voltages on the pins relate as follows:
V OS2 > V OS1 > V CS
The opposite applies when V CTLI < 1.50V current flows
from OS1 to OS2:
V OS2 < V OS1 < V CS
Shutdown Control
The MAX8520/MAX8521 can be placed in a power-saving
shutdown mode by driving SHDN low. When the
MAX8520/MAX8521 are shut down, the TEC is off (OS1
and OS2 decay to GND) and supply current is reduced to
2mA (typ).
ITEC Output
ITEC is a status output that provides a voltage proportional
to the actual TEC current. V ITEC = V REF when TEC current
is zero. The transfer function for the ITEC output is:
V ITEC = 1.50V + 8 (V OS1 – V CS )
Use ITEC to monitor the cooling or heating current
through the TEC. For stability keep the load capaci-
tance on ITEC to less than 150pF.
Applications Information
The MAX8520/MAX8521 typically drive a thermo-elec-
tric cooler inside a thermal-control loop. TEC drive
polarity and power are regulated based on temperature
information read from a thermistor or other temperature-
measuring device to maintain a stable control tempera-
ture. Temperature stability of +0.01°C can be achieved
with carefully selected external components.
There are numerous ways to implement the thermal loop.
Figures 1 and 2 show designs that employ precision op
amps, along with a DAC or potentiometer to set the con-
trol temperature. The loop can also be implemented digi-
tally, using a precision A/D to read the thermistor or other
temperature sensor, a microcontroller to implement the
control algorithm, and a DAC (or filtered-PWM signal) to
send the appropriate signal to the MAX8520/MAX8521
CTLI input. Regardless of the form taken by the thermal-
control circuitry, all designs are similar in that they read
temperature, compare it to a set-point signal, and then
send an error-correcting signal to the MAX8520/
MAX8521 that moves the temperature in the appropriate
direction.
PCB Layout and Routing
High switching frequencies and large peak currents
make PCB layout a very important part of design. Good
design minimizes excessive EMI and voltage gradients
in the ground plane, both of which can result in instabil-
ity or regulation errors. Follow these guidelines for good
PCB layout:
1) Place decoupling capacitors as close to the IC pins
as possible.
2) Keep a separate power ground plane, which is con-
nected to PGND1 and PGND2. PVDD1, PVDD2,
PGND1 and PGND2 are noisy points. Connect decou-
pling capacitors from PVDD_ to PGND_ as direct as
possible. Output capacitors C2, C7 returns are con-
nected to PGND plane.
3) Connect a decoupling capacitor from V DD to GND.
Connect GND to a signal ground plane (separate from
the power ground plane above). Other V DD decoupling
capacitors (such as the input capacitor) need to be
connected to the PGND plane.
4) Connect GND and PGND_ pins together at a single
point, as close as possible to the chip.
5) Keep the power loop, which consists of input capaci-
tors, output inductors and capacitors, as compact and
small as possible.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8520EVKIT | 制造商:Maxim Integrated Products 功能描述:SMALLEST TEC POWER DRIVERS FOR OPTI - Rail/Tube |
| MAX8521EBX | 制造商:Maxim Integrated Products 功能描述:SMALLEST TEC POWER DRIVERS FOR OPTICAL MODULE - Rail/Tube |
| MAX8521EBX+T | 功能描述:其他电源管理 RoHS:否 制造商:Texas Instruments 输出电压范围: 输出电流:4 mA 输入电压范围:3 V to 3.6 V 输入电流: 功率耗散: 工作温度范围:- 40 C to + 110 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-48 封装:Reel |
| MAX8521EBX-T | 功能描述:其他电源管理 RoHS:否 制造商:Texas Instruments 输出电压范围: 输出电流:4 mA 输入电压范围:3 V to 3.6 V 输入电流: 功率耗散: 工作温度范围:- 40 C to + 110 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-48 封装:Reel |
| MAX8521ETP | 功能描述:其他电源管理 RoHS:否 制造商:Texas Instruments 输出电压范围: 输出电流:4 mA 输入电压范围:3 V to 3.6 V 输入电流: 功率耗散: 工作温度范围:- 40 C to + 110 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-48 封装:Reel |
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