MAX1968/MAX1969
Power Drivers for Peltier TEC Modules
Maxim Integrated | 9www.maximintegrated.com
Pin Description
PIN NAME FUNCTION
1
V
DD
Analog Supply Voltage Input
2 GND Analog Ground
3 CTLI
TEC Current Control Input. Sets differential current into the TEC. Center point is 1.50V (no TEC current).
The current is given by:
I
TEC
= (V
OS1
- V
CS
) / R
SENSE
= (V
CTLI
- 1.50) / (10 x R
SENSE
). When (V
CTLI
- V
REF
) > 0, V
OS2
> V
OS1
> V
CS
.
4 REF 1.50V Reference Output. Bypass REF to GND with a 1µF ceramic capacitor.
5, 7 PGND2
Power Ground 2. Internal synchronous rectifier ground connections. Connect all PGND pins together at
power ground plane.
6, 8, 10 LX2 Inductor Connection. Connect all LX2 pins together. For MAX1969, connect LX1 and LX2 pins together.
9, 11
PV
DD
2 Power 2 Inputs. Must be same voltage as V
DD
. Connect all PV
DD
2 inputs together at the V
DD
power plane.
12 FREQ Switching Frequency Select. High = 1MHz, Low = 500kHz.
13 ITEC
TEC Current Monitor Output. The ITEC output voltage is a function of the voltage across the TEC current-
sense resistor. V
ITEC
= 1.50V + (V
OS1
- V
CS
) x 8.
14 OS2
Output Sense 2. OS2 senses one side of the differential TEC voltage. OS2 is a sense point, not a power
output. For MAX1969, connect OS2 to GND.
15 OS1
Output Sense 1. OS1 senses one side of the differential TEC voltage. OS1 is a sense point, not a power
output.
16 CS
Current-Sense Input. The current through the TEC is monitored between CS and OS1. The maximum TEC
current is given by 150mV / R
SENSE
and is bipolar.
17
SHDN
Shutdown Control Input. Active-low shutdown control.
18, 20
PV
DD
1 Power 1 Inputs. Must be same voltage as V
DD
. Connect all PV
DD
1 inputs together at the V
DD
power plane.
19, 21, 23 LX1 Inductor Connection. Connect all LX1 pins together. For MAX1969, connect all LX1 and LX2 pins together.
22, 24 PGND1
Power Ground 1. Internal synchronous rectifier ground connections. Connect all PGND pins together at
power ground plane.
25 COMP Current Control-Loop Compensation. For most designs connect a 0.01µF capacitor from COMP to GND.
26 MAXIN
Maximum Negative TEC Current. Connect MAXIN to REF to set default negative current limit
-150mV / R
SENSE
. For MAX1969, connect MAXIN to MAXIP.
27 MAXIP
M axi m um P osi ti ve TE C C ur r ent. C onnect M AX IP to RE F to set d efaul t p osi ti ve cur r ent l i m i t + 150m V / R
S E N S E
.
(See the Setting Max Positive and Negative TEC Current section).
28 MAXV
Maximum Bipolar TEC Voltage. Connect an external resistive-divider from REF to GND to set the maximum
voltage. The maximum TEC voltage is 4 x V
MAXV
.
—EP
Exposed Pad. Internally connected to GND. Connect to a large ground plane to maximize thermal
performance.
