MAX1978ETM+ Maxim Integrated Products, MAX1978ETM+ Datasheet - Page 12

• Manufacturer Part Number: MAX1978ETM+
• Description: IC CNTRLR INT TEMP 48TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX1978ETM+

• Applications: Thermoelectric Cooler
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-TQFN Exposed Pad
• Output Voltage Range: - 4.3 V to + 4.3 V
• Output Current: 6 A
• Input Voltage Range: 3 V to 5.5 V
• Input Current: 30 mA
• Power Dissipation: 2105 mW
• Operating Temperature Range: - 40 C to + 85 C
• Mounting Style: SMD/SMT
• Ic Output Type: Current
• Sensing Accuracy Range: ± 1%
• Supply Current: 30mA
• Supply Voltage Range: 3V To 5.5V
• Sensor Case Style: QFN
• No. Of Pins: 48
• Filter Terminals: SMD
• Rohs Compliant: Yes
• Temperature Sensing Range: -40°C To +85°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

The power stage of the MAX1978/MAX1979
thermoelectric cooler (TEC) temperature controllers
consists of two switching buck regulators that operate
together to directly control TEC current. This configura-
tion creates a differential voltage across the TEC, allow-
ing bidirectional 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. The
internal thermal-control loop drives CTLI to regulate
Integrated Temperature
Controllers for Peltier Modules
Figure 1. MAX1978 Typical Application Circuit. Circuit is configured for both cooling and heating the NTC thermistor. Current flowing
from OS2 and OS1 is cooling.
12
THERMISTOR
______________________________________________________________________________________
REF
MONITOR
VOLTAGE
80.6kΩ
69.8kΩ
1%
DC CURRENT
UNDERTEMP
OVERTEMP
MONITOR
ALARM
ALARM
105kΩ
1%
Detailed Description
1µF
0.01µF
20kΩ
1%
10µF
COMP
UT
OT
ITEC
BFB-
AIN-
AOUT
AIN+
CTLI
FREQ
GND
V
V
Power Stage
DD
DD
PGND2 PGND1
SHDN
10µF
100kΩ
PV
DD
10µF
0.047µF
1
PV
MAX1978
10µF
DD
INTOUT
1µF
2
TEC temperature. The on-chip thermal-control circuitry
can be configured to achieve temperature control sta-
bility of 0.001°C. Figure 1 shows a typical TEC thermal-
control circuit.
Switching regulators like those used in the
MAX1978/MAX1979 inherently create ripple voltage on
each common-mode output. The regulators in the
MAX1978 switch in phase and provide complementary
in-phase duty cycles, so ripple waveforms at the differ-
ential TEC output are greatly reduced. This feature sup-
presses ripple currents and electrical noise at the TEC
to prevent interference with the laser diode while mini-
mizing output capacitor filter size.
REF
REF MAXV MAXIN MAXIP
INT-
0.47µF
1MΩ
20kΩ
DIFOUT FB+
OS1
OS2
LX1
LX2
FB-
CS
4.7µF
100kΩ
3µH
3µH
Ripple Cancellation
TEC
10kΩ
0.068Ω
1µF
REF
THERMAL
FEEDBACK
1µF