参数资料
| 型号： | MAX1969EUI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 11/16页 |
| 文件大小： | 0K |
| 描述： | IC DRVR POWER 28-TSSOP |
| 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： | 28-SOIC（0.173"，4.40mm 宽）裸露焊盘 |
| 供应商设备封装： | 28-TSSOP 裸露焊盘 |
| 包装： | 带卷 (TR) |
Power Drivers for Peltier TEC Modules
Detailed Description
The MAX1968/MAX1969 TEC drivers consist of two
switching buck regulators that operate together to
directly control TEC current. This configuration creates
a differential voltage across the TEC, allowing bidirec-
tional TEC current for controlled cooling and heating.
Controlled cooling and heating allow accurate TEC
temperature control within the tight tolerances of laser
driver specifications. The voltage at CTLI directly sets
the TEC current. An external thermal-control loop is typ-
ically used to drive CTLI. Figures 1 and 2 show exam-
Design Procedure
Inductor Selection
Small surface-mount inductors are ideal for use with the
MAX1968/MAX1969. 3.3μH inductors are suitable for
most applications. Select the output inductors so that
the LC resonant frequency of the inductance and the
output capacitance is less than 1/5 the selected switch-
ing frequency. For example, 3.3μH and 1μF have a res-
onance at 87.6kHz, which is adequate for 500kHz
operation
ples of thermal control-loop circuits.
Ripple Cancellation
Switching regulators like those used in the
MAX1968/MAX1969 inherently create ripple voltage on
where:
f =
1
2 π LC
C COMP ≥ ? m ? × ?
? f BW ? ? 2 π × ( R SENSE + R TEC ) ?
C COMP ≥ ? m ? × ?
? f BW ? ? 2 π × ( R SENSE TEC ) ?
? ( For MAX 1969 )
the output. The regulators in the MAX1968 switch in
phase and provide complementary in-phase duty cycles
so ripple waveforms at the TEC are greatly reduced. This
feature suppresses ripple currents and electrical noise at
the TEC to prevent interference with the laser diode.
Switching Frequency
FREQ sets the switching frequency of the internal oscil-
lator. With FREQ = GND, the oscillator frequency is set
to 500kHz. The oscillator frequency is 1MHz when
FREQ = V DD .
Voltage and Current-Limit Settings
Both the MAX1968 and MAX1969 provide control of the
maximum differential TEC voltage. Applying a voltage
to MAXV limits the maximum voltage across the TEC.
The MAX1968 provides control of the maximum positive
and negative TEC current. The voltage at MAXIP and
MAXIN sets the maximum positive and negative current
through the TEC. These current limits can be indepen-
dently controlled. The MAX1969 only controls TEC cur-
rent in one direction. The maximum TEC current is
controlled by MAXIP. Connect MAXIN to GND when
using the MAX1969.
Current Monitor Output
ITEC provides a voltage output proportional to the TEC
current (I TEC ). See the Functional Diagram for more
detail:
V ITEC = 1.5V + 8 x (V OS1 - V CS )
Reference Output
The MAX1968/MAX1969 include an on-chip voltage ref-
erence. The 1.50V reference is accurate to 1% over
temperature. Bypass REF with 1μF to GND. REF may
be used to bias an external thermistor for temperature
sensing as shown in Figures 1 and 2.
f = resonant frequency of output filter.
Capacitor Selection
Filter Capacitors
Decouple each power-supply input (V DD , PV DD 1,
PV DD 2) with a 1μF ceramic capacitor close to the supply
pins. In some applications with long distances between
the source supply and the MAX1968/MAX1969, addition-
al bypassing may be needed to stabilize the input sup-
ply. In such cases, a low-ESR electrolytic capacitor of
100μF or more at V DD is usually sufficient.
Compensation Capacitor
A compensation capacitor is needed to ensure current
control-loop stability. Select the capacitor so that the
unity-gain bandwidth of the current control loop is less
than or equal to 1/12th the resonant frequency of the out-
put filter:
? g ? ? 24 × R SENSE ?
? ( For MAX 1968 )
? g ? ? 12 × R SENSE ?
+ R
where:
f BW = loop unity gain bandwidth
g m = loop transconductance, typically 100μA/V
C COMP = value of the compensation capacitor
R TEC = TEC series resistance
R SENSE = sense resistor
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