MAX8520 Datasheet, PDF (1/19 Pages) Maxim Integrated Products – Smallest TEC Power Drivers for Optical Modules

19-2586; Rev 0; 10/02
3mm ^{x 3mm}
CSP
5mm ^{x 5mm}
QFN
Smallest TEC Power Drivers for
Optical Modules
General Description
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.
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.
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.
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.
Applications
SFF/SFP Modules
Fiber-Optic Laser Modules
Fiber-Optic Network Equipment
ATE
Biotech Lab Equipment
Pin Configurations appear at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
Features
o Circuit Footprint of 0.31in²
o Low-Profile Design
o On-Chip Power MOSFETs
o High-Efficiency Switch-Mode Design
o Ripple Cancellation for Low Noise
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
o 1% Accurate Voltage Reference
o Switching Frequency Up to 1MHz
o Synchronization (MAX8521)
Ordering Information
PART
MAX8520ETP
MAX8521EBX
MAX8521ETP
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
20 Thin QFN 5mm x 5mm
36 UCSP 3mm x 3mm
20 Thin QFN 5mm x 5mm
INPUT
3V TO 5.5V
ON
OFF
TEC CURRENT
MONITOR
CURRENT-
CONTROL
SIGNAL
Typical Operating Circuit
VDD
PVDD
FREQ
LX1
PGND1
SHDN
CS
ITEC MAX8521
CTLI
OS1
COMP
REF
GND
OS2
LX2
PGND2
ANALOG /DIGITAL
TEMPERATURE CONTROL
OUTPUT
TEC ^{ITEC = ± 1.5A}
________________________________________________________________ Maxim Integrated Products 1
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