Datasheet

Buffered Outputs, BFB+ and BFB-
BFB+ and BFB- output a buffered version of the voltage
that appears on FB+ and FB-, respectively. The buffers
are typically used in conjunction with the undedicated
chopper amplifier to create a monitor for the thermistor
voltage/TEC temperature (Figures 1 and 2). These
buffers are unity-gain chopper amplifiers and exhibit
output ripple. Each output can be either integrated or
filtered to remove the ripple content if necessary.
Undedicated Chopper-Stabilized Amplifier
In addition to the chopper amplifiers at DIFOUT and
BFB_, the MAX1978/MAX1979 include an additional
chopper amplifier at AOUT. This amplifier is uncommit-
ted but is intended to provide a temperature-propor-
tional analog output. The thermistor voltage typically is
connected to the undedicated chopper amplifier
through the included buffers BFB+ and BFB-. Figure 3
shows how to configure the undedicated amplifier as a
thermistor voltage monitor. The output voltage at AOUT
is not precisely linear, because the thermistor is not lin-
ear. AOUT is also chopper stabilized and exhibits out-
put ripple and can be either integrated or filtered to
remove the ripple content if necessary.
Integrated Temperature
Controllers for Peltier Modules
TEC
MAX1979
10µF
10µF 10µF 1µF
0.01µF
V
DD
V
DD
SHDN
PV
DD
1PV
DD
2
REF
REF MAXV MAXIN MAXIP
UNDERTEMP
ALARM
COMP
OVERTEMP
ALARM
DC CURRENT
MONITOR
REF
ITEC
BFB-
AIN-
AIN+
CTLI
FREQ
GND PGND2 PGND1 INTOUT INT- DIFOUT
FB-
FB+
OS2
OS1
CS
LX2
LX1
AOUT
20kΩ
1%
69.8kΩ
1%
105kΩ
1%
1µF
THERMISTOR
VOLTAGE
MONITOR
80.6kΩ
100kΩ
100kΩ
0.03Ω
10kΩ
3µH
4.7µF
1µF
20kΩ
1MΩ
10µF
0.047µF
0.47µF
REF
THERMAL
FEEDBACK
UT
OT
Figure 2. MAX1979 Typical Application Circuit. MAXIN sets the maximum TEC current circuit configured for cooling with NTC ther-
mistor. Current always flow from CS and OS2.
MAX1978/MAX1979
14
Maxim Integrated