19-2447; Rev 0; 4/02
KIT
ATION
EVALU
BLE
AVAILA
Power Drivers for Peltier TEC Modules
General Description
Features
o
Direct Current Control Prevents TEC Current
Surges
o
On-Chip Power MOSFETs
o
High-Efficiency Switch-Mode Design
o
Ripple Cancellation for Low Noise
o
No Dead-Zone or Hunting at Low-Output Current
o
Adjustable TEC Voltage Limit
o
Separately Adjustable Heating and Cooling
Current Limits
o
ITEC Output Monitors TEC Current
o
1% Accurate Voltage Reference
o
500kHz/1MHz Switching Frequency
o
±3A
Output Current (MAX1968)
o
6A Output Current (MAX1969)
o
Thermally Enhanced TSSOP-EP Package
MAX1968/MAX1969
The MAX1968/MAX1969 are highly integrated and cost-
effective, high-efficiency, switch-mode drivers for Peltier
thermoelectric cooler (TEC) modules. Both devices uti-
lize 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 independently 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.
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 paddle
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
MAX1968
LX2
GND
LX1
OS2
OS2
CS
V
DD
PV
DD
1
PV
DD
2
PGND1
PGND2
3V TO
TEC
CURRENT- 5.5V
CONTROL
SIGNAL
Typical Operating Circuit
TEC
Pin Configuration and Functional Diagram appear at end
of datasheet.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Power Drivers for Peltier TEC Modules
MAX1968/MAX1969
ABSOLUTE MAXIMUM RATINGS
V
DD
to GND ..............................................................-0.3V to +6V
SHDN,
MAXV, MAXIP, MAXIN, CTLI,
FREQ to GND .......................................................-0.3V to +6V
COMP, OS1, OS2, CS, REF,
ITEC to GND ...........................................-0.3V to (V
DD
+ 0.3V)
PV
DD
1, PV
DD
2 to GND ...............................-0.3V to (V
DD
+ 0.3V)
PV
DD
1, PV
DD
2 to V
DD ..................................................
-0.3V to +0.3V
PGND1, PGND2 to GND .......................................-0.3V to +0.3V
COMP, REF, ITEC Short to GND ...................................Indefinite
Peak LX Current (MAX1968) (Note 1).................................±4.5A
Peak LX Current (MAX1969) (Note 1)....................................+9A
Continuous Power Dissipation (T
A
= +70°C)
28-Pin TSSOP-EP (derate 23.8mW/°C above +70°C).....1.9W
Operating Temperature Range ...........................-40°C to +85°C
Maximum Junction Temperature .....................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering 10s) ..................................+300°C
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
∆V
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
2
_______________________________________________________________________________________
Power Drivers for Peltier TEC Modules
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= PV
DD
1 = PV
DD
2 =
SHDN
= 5V, PGND1 = PGND2 = FREQ = GND, CTLI = MAXV = MAXIP = MAXIN = REF, C
REF
= 1µF,
C
COMP
= 0.01µF, 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
PFET Leakage
No Load Supply
Current
Shutdown Supply
Current
Thermal Shutdown
UVLO Threshold
Switching Frequency
Internal Oscillator
OS1, OS2, CS Input
Current
SHDN,
FREQ Input
Current
SHDN,
FREQ Input
Low Voltage
SHDN,
FREQ Input
High Voltage
SYMBOL
I
LEAK(P)
I
DD
(NO LOAD)
MAX1968/MAX1969
CONDITIONS
V
LX
= 0, T
A
= +25°C
V
LX
= 0, T
A
= +85°C
V
DD
= 5V
V
DD
= 3.3V
V
DD
= 5V (Note 2)
MIN
TYP
0.02
1
32
20
2
+165
MAX
10
UNITS
µA
100
30
3
mA
mA
°C
I
DD-SD
T
SHUTDOWN
Hysteresis = 15°C
V
UVLO
f
SW-INT
I
OS1
,
I
OS2
, I
CS
I
SHDN
,
I
FREQ
V
IL
V
IH
V
DD
rising
V
DD
falling
FREQ = GND
0 or V
DD
0 or V
DD
V
DD
= 3V to 5.5V
V
DD
= 3V to 5.5V
V
MAXV
= V
REF
x 0.67, V
OS1
to V
OS2
=
±4V,
V
DD
= 5V
V
MAXV
= V
REF
x 0.33, V
OS1
to V
OS2
=
±2V,
V
DD
= 3V
I
MAXV-BIAS
,
I
MAXI_-BIAS
A
CTLI
R
CTLI
g
m
V
OS1
to V
CS
= +100mV or -100mV
∆V
ITEC
V
OS1
to V
CS
= +100mV or -100mV,
I
ITEC
=
±10µA
V
MAXV
= V
MAXI_
= 0.1V or 1.5V
V
CTLI
= 0.5V to 2.5V (Note 3)
1MΩ terminated at REF
V
DD
x
0.75
-2
-2
-0.1
9.5
0.5
50
-10
-0.1
2.4
2.25
400
-100
-5
2.6
2.5
550
2.8
2.75
650
+100
+5
V
DD
x
0.25
V
kHz
µA
µA
V
V
+2
+2
+0.1
10
1.0
100
10.5
2.0
175
+10
+0.1
%
%
µA
V/V
MΩ
µA/V
%
%
MAXV Threshold
Accuracy
MAXV, MAXIP, MAXIN
Input Bias Current
CTLI Gain Accuracy
CTLI Input Resistance
Error-Amp
Transconductance
ITEC Accuracy
ITEC Load Regulation
_______________________________________________________________________________________
3
Power Drivers for Peltier TEC Modules
MAX1968/MAX1969
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
= -40°C to +85°C,
unless
otherwise noted.) (Note 4)
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
∆V
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
PFET Leakage
No Load Supply
Current
Shutdown Supply
Current
UVLO Threshold
Switching-Frequency
Internal Oscillator
R
DS(ON-N)
R
DS(ON-P)
I
LEAK(N)
I
LEAK(P)
I
DD(NO
LOAD)
CONDITIONS
MIN
3.0
-4.3
TYP
MAX
5.5
+4.3
4.3
UNITS
V
Output Voltage Range
V
OUT
V
-2.3
+2.3
2.3
±3
6
1.475
1.515
5
135
35
135
35
50
165
65
165
65
250
0.07
0.08
0.07
0.12
10
10
10
10
100
30
3
2.4
2.25
400
2.8
2.75
650
mV
Ω
Ω
µA
µA
mA
mA
V
kHz
mV
A
V
mV
V
MAXI_
= V
REF
V
MAXI_
= V
REF
/ 3
V
MAXI_
= V
REF
V
MAXI_
= V
REF
/ 3
Current-Sense
Threshold Accuracy
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
= -40°C
V
LX
= 0, T
A
= +25°C
V
LX
= 0, T
A
= -40°C
V
DD
= 5V
V
DD
= 3.3V
SHDN
= GND, V
DD
= 5V (Note 2)
V
DD
rising
V
DD
falling
FREQ = GND
I
DD-SD
V
UVLO
f
SW-INT
4
_______________________________________________________________________________________
Power Drivers for Peltier TEC Modules
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= PV
DD
1 = PV
DD
2 =
SHDN
= 5V, PGND1 = PGND2 = FREQ = GND, CTLI = MAXV = MAXIP = MAXIN = REF, C
REF
= 1µF,
C
COMP
= 0.01µF, L
LX_
= 3.3µH, C
CS
= C
OS2
= 1µF, I
TEC
< 3A
RMS
(MAX1968), I
TEC
< 6A
RMS
(MAX1969),
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 4)
PARAMETER
OS1, OS2, CS Input
Current
SHDN,
FREQ Input
Current
SHDN,
FREQ Input
Low Voltage
SHDN,
FREQ Input
High Voltage
SYMBOL
I
OS1
,
I
OS2
, I
CS
I
SHDN
,
I
FREQ
V
IL
V
IH
0 or V
DD
0 or V
DD
V
DD
= 3V to 5.5V
V
DD
= 3V to 5.5V
V
MAXV
= V
REF
x 0.67, V
OS1
to V
OS2
=
±4V,
V
DD
= 5V
V
MAXV
= V
REF
x 0.33, V
OS1
to V
OS2
=
±2V,
V
DD
= 3V
I
MAXV-BIAS
,
I
MAXI_-BIAS
A
CTLI
R
CTLI
g
m
V
OS1
to V
CS
= +100mV or -100mV
V
MAXV
= V
MAXI_
= 0.1V or 1.5V
V
CTLI
= 0.5V to 2.5V (Note 3)
1MΩ terminated at REF
-0.1
9.5
0.5
50
-10
+0.1
10.5
2.0
175
+10
µA
V/V
MΩ
µA/V
%
V
DD
x
0.75
CONDITIONS
MIN
-100
-5
TYP
MAX
+100
+5
V
DD
x
0.25
V
UNITS
µA
µA
MAX1968/MAX1969
MAXV Threshold
Accuracy
-2
+2
%
MAXV, MAXIP, MAXIN
Input Bias Current
CTLI Gain Accuracy
CTLI Input Resistance
Error-Amp
Transconductance
ITEC Accuracy
Note 2:
Includes power FET leakage.
Note 3:
CTLI Gain is defined as:
A
CTLI
=
(V
CTLI
−
V
REF
)
V
OS1
−
V
CS
Note 4:
Specifications to -40°C are guaranteed by design, not production tested.
_______________________________________________________________________________________
5
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