MAX1978 Datasheet, PDF (1/20 Pages) Maxim Integrated Products – Integrated Temperature Controllers for Peltier Modules

19-2490; Rev 0; 7/02
EVAALVUAAILTAIOBNLEKIT
Integrated Temperature
Controllers for Peltier Modules
General Description
The MAX1978/MAX1979 are the smallest, safest, most
accurate complete single-chip temperature controllers for
Peltier thermoelectric cooler (TEC) modules. On-chip power
FETs and thermal control-loop circuitry minimize external
components while maintaining high efficiency. Selectable
500kHz/1MHz switching frequency and a unique ripple-can-
cellation scheme optimize component size and efficiency
while reducing noise. Switching speeds of internal
MOSFETs are optimized to reduce noise and EMI. An ultra-
low-drift chopper amplifier maintains ±0.001°C temperature
stability. Output current, rather than voltage, is directly con-
trolled to eliminate current surges. Individual heating and
cooling current and voltage limits provide the highest level of
TEC protection.
The MAX1978 operates from a single supply and provides
bipolar ±3A output by biasing the TEC between the outputs
of two synchronous buck regulators. True bipolar operation
controls temperature without “dead zones” or other nonlin-
earities at low load currents. The control system does not
hunt when the set point is very close to the natural operating
point, where only a small amount of heating or cooling is
needed. An analog control signal precisely sets the TEC
current. The MAX1979 provides unipolar output up to 6A.
A chopper-stabilized instrumentation amplifier and a high-
precision integrator amplifier are supplied to create a pro-
portional-integral (PI) or proportional-integral-derivative (PID)
controller. The instrumentation amplifier can interface to an
external NTC or PTC thermistor, thermocouple, or semicon-
ductor temperature sensor. Analog outputs are provided to
monitor TEC temperature and current. In addition, separate
overtemperature and undertemperature outputs indicate
when the TEC temperature is out of range. An on-chip volt-
age reference provides bias for a thermistor bridge.
The MAX1978/MAX1979 are available in a low-profile
48-lead thin QFN-EP package and is specified over the
-40°C to +85°C temperature range. The thermally
enhanced QFN-EP package with exposed metal pad
minimizes operating junction temperature. An evaluation
kit is available to speed designs.
Applications
Fiber Optic Laser Modules
WDM, DWDM Laser-Diode Temperature Control
Fiber Optic Network Equipment
EDFA Optical Amplifiers
Telecom Fiber Interfaces
ATE
Typical Operating Circuit appears at end of data sheet.
Features
o Smallest, Safest, Most Accurate Complete
Single-Chip Controller
o On-Chip Power MOSFETS—No External FETs
o Circuit Footprint < 0.93in²
o Circuit Height < 3mm
o Temperature Stability to 0.001°C
o Integrated Precision Integrator and Chopper
Stabilized Op Amps
o Accurate, Independent Heating and Cooling
Current Limits
o Eliminates Surges By Directly Controlling
TEC Current
o Adjustable Differential TEC Voltage Limit
o Low-Ripple and Low-Noise Design
o TEC Current Monitor
o Temperature Monitor
o Over- and Undertemperature Alarm
o Bipolar ±3A Output Current (MAX1978)
o Unipolar +6A Output Current (MAX1979)
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX1978ETM
-40°C to +85°C 48 Thin QFN-EP*
MAX1979ETM
-40°C to +85°C 48 Thin QFN-EP
*EP = Exposed pad.
Pin Configuration
TOP VIEW
OS2 1
N.C. 2
PGND2 3
LX2 4
PGND2 5
LX2 6
PVDD2 7
N.C. 8
LX2 9
PVDD2 10
SHDN 11
OT 12
MAX1978
MAX1979
36 FREQ
35 N.C.
34 PGND1
33 LX1
32 PGND1
31 LX1
30 PV_DD1
29 N.C.
28 LX1
27 PV_DD1
26 GND
25 GND
QFN-EP
*ELECTRICALLY CONNECTED TO THE UNDERSIDE METAL SLUG.
NOTE: GND IS CONNECTED TO THE UNDERSIDE METAL SLUG.
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