EVALUATION KIT AVAILABLE
MAX1968/MAX1969
Power Drivers for Peltier TEC Modules
General Description
The MAX1968/MAX1969 are highly integrated and cost-
effective, high-efficiency, switch-mode drivers for Peltier
thermoelectric cooler (TEC) modules. Both devices
utilize direct current control to eliminate current surges
in the TEC. On-chip FETs minimize external components
while providing high efficiency. A 500kHz/1MHz switch-
ing frequency and a unique ripple cancellation scheme
reduce component size and noise.
The MAX1968 operates from a single supply and pro-
vides bipolar
±3A
output by biasing the TEC between
the outputs of two synchronous buck regulators.
Bipolar operation allows for temperature control without
“dead zones” or other nonlinearities at low load
currents. This arrangement ensures that the control
system does not hunt when the set point is very close
to the natural operating point, requiring a small amount
of heating or cooling. An analog control signal precisely
sets the TEC current. The MAX1969 provides unipolar
output up to 6A. Reliability is optimized with settable
limits for both TEC voltage and current, with indepen-
dently set limits for heating and cooling current. An
analog output also monitors TEC current.
The MAX1968/MAX1969 are available in a low-profile
28-pin TSSOP-EP package and is specified over the
-40°C to +85°C temperature range. The thermally
enhanced TSSOP-EP package with exposed metal pad
minimizes operating junction temperature. An evalua-
tion kit is available to speed designs.
Benefits and Features
•
High Accuracy and Adjustability Improves System
Performance by Optimizing TEC Operation
•
Direct Current Control Prevents TEC Current Surges
•
Ripple Cancellation for Low Noise
•
No Dead-Zone or Hunting at Low-Output Current
•
1% Accurate Voltage Reference
•
Adjustable TEC Voltage Limit
•
Separately Adjustable Heating and Cooling Current
Limits
•
ITEC Output Provides Proportional Voltage to TEC
Current for Monitoring
•
High-Efficiency Switch-Mode Design
•
On-Chip Power MOSFETs Improve Efficiency While
Reducing External Components
•
500kHz/1MHz Switching Frequency
•
Choose from ±3A Output Current (MAX1968) or 6A
Output Current (MAX1969)
•
Thermally Enhanced TSSOP-EP Package Minimizes
Operating Junction Temperature
Ordering Information
PART
MAX1968EUI
MAX1969EUI
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
28 TSSOP-EP*
28 TSSOP-EP*
*EP
= Exposed pad.
Applications
Fiber Optic Laser Modules
WDM, DWDM Laser Diode Temperature Control
Fiber Optic Network Equipment
EDFA Optical Amplifiers
Telecom Fiber Interfaces
ATE
Biotech Lab Equipment
CTLI
COMP
LX2
GND
V
DD
PV
DD
1
MAX1968
LX1
OS2
OS1
CS
PV
DD
2
PGND1
PGND2
Typical Operating Circuit
3V TO
TEC
CURRENT- 5.5V
CONTROL
SIGNAL
TEC
Pin Configuration and Functional Diagram appear at end
of data sheet.
19-2447; Rev 3; 5/15
MAX1968/MAX1969
Power Drivers for Peltier TEC Modules
Absolute Maximum Ratings
V
DD
to GND ..............................................................-0.3V to +6V
Peak LX Current (MAX1968) (Note 1).................................±4.5A
Peak LX Current (MAX1969) (Note 1)....................................+9A
SHDN,
MAXV, MAXIP, MAXIN, CTLI,
Continuous Power Dissipation (T
A
= +70°C)
FREQ to GND .......................................................-0.3V to +6V
28-Pin TSSOP-EP (derate 23.8mW/°C above +70°C).....1.9W
COMP, OS1, OS2, CS, REF,
Operating Temperature Range ...........................-40°C to +85°C
ITEC to GND ...........................................-0.3V to (V
DD
+ 0.3V)
Maximum Junction Temperature .....................................+150°C
PV
DD
1, PV
DD
2 to GND ...............................-0.3V to (V
DD
+ 0.3V)
Storage Temperature Range .............................-65°C to +150°C
PV
DD
1, PV
DD
2 to V
DD ..................................................
-0.3V to +0.3V
Lead Temperature (soldering 10s) ..................................+300°C
PGND1, PGND2 to GND .......................................-0.3V to +0.3V
COMP, REF, ITEC Short to GND ...................................Indefinite
Note 1:
LX has internal clamp diodes to PGND and PV
DD_
. Applications that forward bias these diodes should take care not to
exceed the IC’s package power dissipation limits.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Electrical Characteristics
(V
DD
= PV
DD
1 = PV
DD
2 =
SHDN
= 5V, PGND1 = PGND2 = FREQ = GND, CTLI = MAXV = MAXIP = MAXIN = REF, C
REF
= 1µF,
C
COMP
= 0.1µF, L
LX_
= 3.3µH, C
CS
= C
OS2
= 1µF, I
TEC
< 3A
RMS
(MAX1968), I
TEC
< 6A
RMS
(MAX1969),
T
A
= 0°C to +85°C,
unless
otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Input Supply Range
SYMBOL
V
DD
V
DD
= 5V, I
TEC
= 0 to
±3A,
V
OUT
= V
OS1
- V
OS2
(MAX1968)
V
DD
= 5V, I
TEC
= 0 to 6A,
V
OUT
= V
OS1
(MAX1969)
V
DD
= 3V, I
TEC
= 0 to
±3A,
V
OUT
= V
OS1
- V
OS2
(MAX1968)
V
DD
= 3V, I
TEC
= 0 to 6A,
V
OUT
= V
OS1
(MAX1969)
Maximum TEC
Current
Reference Voltage
Reference Load
Regulation
I
TEC(MAX)
V
REF
ΔV
REF
MAX1968
MAX1969
V
DD
= 3V to 5.5V, I
REF
= 150µA
V
DD
= 3V to 5.5V, I
REF
= +10µA to -1mA
V
OS1
< V
CS
V
OS1
> V
CS
Switch-Fault Reset
Voltage
NFET On-Resistance
PFET On-Resistance
NFET Leakage
R
DS(ON-N)
R
DS(ON-P)
I
LEAK(N)
V
DD
= 5V, I = 0.5A
V
DD
= 3V, I = 0.5A
V
DD
= 5V, I = 0.5A
V
DD
= 3V, I = 0.5A
V
LX
= V
DD
= 5V, T
A
= +25°C
V
LX
= V
DD
= 5V, T
A
= +85°C
V
MAXI_
= V
REF
V
MAXI_
= V
REF
/3
V
MAXI_
= V
REF
V
MAXI_
= V
REF
/3
140
40
140
40
50
1.485
1.500
1.2
150
50
150
50
150
0.04
0.06
0.06
0.09
0.02
1
-2.3
CONDITIONS
MIN
3.0
-4.3
TYP
MAX
5.5
+4.3
4.3
V
+2.3
2.3
±3
6
1.515
5
160
60
160
60
250
0.07
0.08
0.10
0.12
10
mV
Ω
Ω
µA
mV
A
V
mV
UNITS
V
Output Voltage Range
V
OUT
Current-Sense
Threshold Accuracy
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