MAX1978ETM+ Maxim Integrated Products, MAX1978ETM+ Datasheet - Page 15

• Manufacturer Part Number: MAX1978ETM+
• Description: IC CNTRLR INT TEMP 48TQFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX1978ETM+

• Applications: Thermoelectric Cooler
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-TQFN Exposed Pad
• Output Voltage Range: - 4.3 V to + 4.3 V
• Output Current: 6 A
• Input Voltage Range: 3 V to 5.5 V
• Input Current: 30 mA
• Power Dissipation: 2105 mW
• Operating Temperature Range: - 40 C to + 85 C
• Mounting Style: SMD/SMT
• Ic Output Type: Current
• Sensing Accuracy Range: ± 1%
• Supply Current: 30mA
• Supply Voltage Range: 3V To 5.5V
• Sensor Case Style: QFN
• No. Of Pins: 48
• Filter Terminals: SMD
• Rohs Compliant: Yes
• Temperature Sensing Range: -40°C To +85°C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Figure 3. Thermistor Voltage Monitor
Small surface-mount inductors are ideal for use with the
MAX1978/MAX1979. Select the output inductors so that
the LC resonant frequency of the inductance and the
output capacitance is less than 1/5 the selected switch-
ing frequency. For example, 3.0µH and 1µF have a res-
onance at 92kHz, which is adequate for 500kHz
operation.
¡
where:
f
Decouple each power-supply input (V
PV
ply pins. If long supply lines separate the source sup-
ply from the MAX1978/MAX1979, or if the source
supply has high output impedance, place an additional
LC
DD
= resonant frequency of output filter.
2) with a 10µF ceramic capacitor close to the sup-
x50
MAX1978
MAX1979
______________________________________________________________________________________
f
LC
AOUT
BFB-
AIN+
AIN-
FB-
FB+
=
2π
Design Procedure
1
LC
Capacitor Selection
REF
Inductor Selection
69.8kΩ
1%
80.6kΩ
1%
20kΩ
1%
V
SETPOINT
105kΩ
1%
Filter Capacitors
DD
Controllers for Peltier Modules
, PV
1µF
REF
DD
10kΩ
1, and
Integrated Temperature
22µF to 100µF ceramic capacitor between the V
power plane and power ground. Insufficient supply
bypassing can result in supply bounce and degraded
accuracy.
Include a compensation capacitor to ensure current-
power control-loop stability. Select the capacitor so that
the unity-gain bandwidth of the current-control loop is
less than or equal to 10% the resonant frequency of the
output filter:
where:
f
g
C
R
R
Consider TEC parameters to guarantee a robust
design. These parameters include maximum positive
current, maximum negative current, and the maximum
voltage allowed across the TEC. These limits should be
used to set 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:
BW
m
MAXI_
TEC
SENSE
COMP
= loop transconductance, typically 100µA/V
= unity-gain bandwidth frequency
TECN(MAX)
MAXI_
Setting Max Positive and Negative TEC Current
C
= TEC series resistance
I
I
COMP
TECP(MAX)
TEC
TEC
is related to ITEC by the following equations:
= value of the compensation capacitor
= sense resistor
V
V
Setting Voltage and Current Limits
. Use resistors in the 10kΩ to 100kΩ range.
MAXIN
MAXIP


≥
R
R
SENSE
⎛
⎜
⎝
SENSE
SENSE
is the maximum negative TEC current.
f
g
BW
= 10 (I
= 10 (I
m
is the maximum positive TEC current
⎞
⎟ ×
⎠
when MAXIP and MAXIN are con-
= CS - OS1 when I
= OS1 - CS when I
⎛
⎜
⎝
TECP(MAX)
TECN(MAX)
2π (
×
Compensation Capacitor
24
R
SENSE
×
R

SENSE

R
R
+
SENSE
SENSE
TEC
TEC
R
TEC
)
< 0.
> 0.
)
)
⎞
⎟
⎠
DD
15