MAX1968EUI+ Maxim Integrated Products, MAX1968EUI+ Datasheet - Page 12

• Manufacturer Part Number: MAX1968EUI+
• Description: IC DRVR POWER 28-TSSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX1968EUI+

• Applications: Thermoelectric Cooler
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-TSSOP Exposed Pad, 28-eTSSOP, 28-HTSSOP
• Output Voltage Range: - 4.3 V to + 4.3 V
• Output Current: 3 A
• Input Voltage Range: 3 V to 5.5 V
• Input Current: 30 mA
• Power Dissipation: 1.9 W
• Operating Temperature Range: - 40 C to + 85 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Power Drivers for Peltier TEC Modules
Certain TEC parameters must be considered to guaran-
tee a robust design. These include maximum positive
current, maximum negative current, and the maximum
voltage allowed across the TEC. These limits should be
used to set the MAXIP, MAXIN, and MAXV voltages.
MAXIP and MAXIN set the maximum positive and nega-
tive TEC currents, respectively. The default current limit
is ±150mV / R
nected to REF. To set maximum limits other than the
defaults, connect a resistor-divider from REF to GND to
set V
V
where I
and I
Positive TEC current occurs when CS is less than OS1:
when I
when I
The MAX1969 controls the TEC current in one direction
(unipolar current flow from OS1 to CS). Set the maxi-
mum unipolar TEC current by applying a voltage to
MAXIN. Connect MAXIP to MAXIN. The equation for
setting MAXIN is the same for the MAX1968 and
MAX1969.
Take care not to exceed the positive or negative cur-
rent limit on the TEC. Refer to the manufacturer’s data
sheet for these limits.
Apply a voltage to the MAXV pin to control the maxi-
mum differential TEC voltage. MAXV can vary from 0 to
REF. The voltage across the TEC is four times V
and can be positive or negative:
Set V
GND using resistors from 10kΩ to 100kΩ. V
vary from 0 to REF.
12
MAXI_
______________________________________________________________________________________
TECN(MAX)
MAXI_
MAXV
TEC
TEC
TECP(MAX)
is related to I
V
V
Setting Voltage and Current Limits
> 0.
< 0.
. Use resistors in the 10kΩ to 100kΩ range.
MAXIN
MAXIP
with a resistor-divider between REF and
I
I
SENSE
TEC
TEC
|V
is the negative maximum TEC current.
OS1
= 10(I
= 10(I
is the maximum positive TEC current
x R
x R
TEC
- V
when MAXIP and MAXIN are con-
SENSE
SENSE
Setting MAX TEC Voltage
Setting Max Positive and
OS2
TECP(MAX
TECN(MAX
by the following equations:
Negative TEC Current
| = 4 x V
= V
= V
OS1
CS
) x R
) x R
- V
MAXV
- V
OS1
SENSE
SENSE
CS
)
)
MAXV
MAXV
can
The voltage at CTLI directly sets the TEC current. CTLI
is typically driven from the output of a temperature con-
trol loop. For the purposes of the following equations, it
is assumed that positive TEC current is cooling (see
Figure 1). The transfer function relating current through
the TEC (I
where V
CTLI is centered around REF (1.50V). I
CTLI = 1.50V. When VCTLI > 1.50V the MAX1968 is
cooling. Current flow is from OS2 to OS1. The voltages
on the pins relate as follows:
The opposite applies when heating. When V
1.50V current flows from OS1 to OS2:
The MAX1968/MAX1969 can be placed in a power-sav-
ing shutdown mode by driving SHDN low. When the
MAX1968/MAX1969 are shut down, the TEC is off (OS1
and OS2 decay to GND) and supply current is reduced
to 2mA (typ).
ITEC is a status output that provides a voltage proportion-
al to the actual TEC current. ITEC = REF when TEC cur-
rent is zero. The transfer function for the ITEC output is:
Use ITEC to monitor the cooling or heating current
through the TEC. The maximum capacitance that ITEC
can drive is 100pF.
REF
TEC
I
TEC
V
is 1.50V and:
ITEC
) and V
I
TEC
= (V
V
V
= 1.50 + 8 x (V
= (V
CTLI
OS2
OS2
CTLI
OS1
> V
< V
- V
is given by:
Control Inputs/Outputs
REF
OS1
OS1
- V
)/(10 x R
CS
Output Current Control
> V
< V
)/R
OS1
CS
CS
SENSE
Shutdown Control
- V
SENSE
TEC
CS
ITEC Output
)
is zero when
)
CTLI
<