19-2586; Rev 0; 10/02
Smallest TEC Power Drivers for
Optical Modules
General Description
Features
o Circuit Footprint of 0.31in2
o Low-Profile Design
The MAX8520/MAX8521 are designed to drive thermo-
electric coolers (TECs) in space-constrained optical
modules. Both devices deliver 1.5A output current
and control the TEC current to eliminate harmful current
surges. On-chip FETs minimize external components and
high switching frequency reduces the size of external
components.
o On-Chip Power MOSFETs
o High-Efficiency Switch-Mode Design
o Ripple Cancellation for Low Noise
The MAX8520 and MAX8521 operate from a single supply
and bias the TEC between the outputs of two synchro-
nous buck regulators. This operation allows for temper-
ature control without “dead zones” or other nonlinearities
at low current. 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.
o Direct Current Control Prevents TEC Current
Surges
o 5% Accurate Adjustable Heating/Cooling Current
Limits
o 2% Accurate TEC Voltage Limit
o No Dead Zone or Hunting at Low Output Current
o ITEC Monitors TEC Current
Both devices feature accurate, individually adjustable
heating current limit and cooling current limit, along
with maximum TEC voltage limit to improve the reliability
of optical modules. An analog output signal monitors
the TEC current. A unique ripple cancellation scheme
helps reduce noise.
o 1% Accurate Voltage Reference
o Switching Frequency Up to 1MHz
o Synchronization (MAX8521)
The MAX8520 is available in a 5mm x 5mm thin QFN
package and its switching frequency is adjustable up to
1MHz through an external resistor. The MAX8521 is also
available in a 5mm x 5mm thin QFN, as well as a space-
saving 3mm x 3mm UCSP™, with a pin-selectable
switching frequency of 500kHz or 1MHz.
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX8520ETP -40°C to +85°C
MAX8521EBX -40°C to +85°C
20 Thin QFN 5mm x 5mm
36 UCSP 3mm x 3mm
20 Thin QFN 5mm x 5mm
Applications
MAX8521ETP
-40°C to +85°C
SFF/SFP Modules
Fiber-Optic Laser Modules
Fiber-Optic Network Equipment
ATE
Typical Operating Circuit
Biotech Lab Equipment
INPUT
V
LX1
PGND1
CS
DD
PV
3V TO 5.5V
DD
FREQ
ON
SHDN
ITEC
OFF
TEC CURRENT
MONITOR
MAX8521
OUTPUT
OS1
CURRENT-
CONTROL
SIGNAL
CTLI
I
= 1.5A
TEC
TEC
OS2
LX2
COMP
REF
PGND2
GND
Pin Configurations appear at end of data sheet.
ANALOG /DIGITAL
TEMPERATURE CONTROL
UCSP is a trademark of Maxim Integrated Products, Inc.
________________________________________________________________ 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.