Smallest TEC Power Drivers for
Optical Modules
Typical Operating Characteristics (continued)
(V
DD
= 5V, circuit of Figure 1, T = +25°C unless otherwise noted)
A
THERMAL STABILITY,
COOLING MODE
THERMAL STABILITY,
ROOM TEMPERATURE
THERMAL STABILITY,
HEATING MODE
MAX8520/21 toc22
MAX8520/21 toc20
MAX8520/21 toc21
TEMPERATURE
0.001°C/div
TEMPERATURE
0.001°C/div
TEMPERATURE
0.001°C/div
T
T
= +25°C
T
T
= +25°C
T
T
= +25°C
TEC
= +5°C
A
TEC
TEC
= +45°C
= +25°C
A
A
4s/div
4s/div
4s/div
Pin Description
PIN
NAME
FUNCTION
QFN
UCSP
1
E1, E2
LX1
Inductor Connection. LX1 is high-impedance in shutdown.
Power Ground 1. Internal synchronous-rectifier ground connection. Connect all PGND
pins together at power ground plane.
2
D1, D2, D3
PGND1
3
4
C1
C2
SHDN
Shutdown Control Input. Pull SHDN low to turn off PWM control and ITEC output.
Current-Control Loop Compensation. Refer to the Compensation Capacitor section.
COMP
TEC Current-Monitor Output. The ITEC output voltage is a function of the voltage across
5
6
7
B1
A1
A2
ITEC
the TEC current-sense resistor. V
<150pF.
= V
+ 8 (V - V ). Keep capacitance on ITEC
REF OS CS
ITEC
Maximum Negative TEC Current. Connect MAXIN to REF to set default negative current
limit to -150mV/R . To lower this current limit, connect MAXIN to a resistor divider
SENSE
MAXIN
MAXIP
network from REF to GND. The current limit will then be equal to -(V
/V
) x
MAXIN REF
(150mV/R
).
SENSE
Maximum Positive TEC Current. Connect MAXIP to REF to set default positive current limit
to 150mV/R . To lower this current limit, connect MAXIP to a resistor divider network
SENSE
from REF to GND. The current limit will then be equal to (V
/V
) x (150mV/R
).
MAXIP REF
SENSE
Maximum Bipolar TEC Voltage. Connect MAXV to REF to set default maximum TEC
voltage to V . To lower this limit, connect MAXV to a resistor-divider network from REF to
8
9
A3
A4
MAXV
REF
DD
GND. The maximum TEC voltage is equal to 4 x V
or V , whichever is lower.
DD
MAXV
1.50V Reference Output. Bypass REF to GND with a 0. 1µF ceramic capacitor.
8
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MAXIM [ MAXIM INTEGRATED PRODUCTS ]
