Ultracompact, 3 A

Thermoelectric Cooler (TEC) Controller

Data Sheet

ADN8835

Rev. B

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FEATURES

High efficiency single inductor architecture

TEC voltage and current operation monitoring

No external sense resistor required

Independent TEC heating and cooling current-limit settings

Programmable maximum TEC voltage

2.0 MHz (typical) PWM driver switching frequency

External synchronization

Two integrated, zero-drift, rail-to-rail chopper amplifiers

Compatible with NTC or RTD thermal sensors

2.50 V reference output with 1% accuracy

Temperature lock indicator

Available in a 36-lead, 6 mm × 6 mm LFCSP

APPLICATIONS

TEC temperature control

Optical modules

Optical fiber amplifiers

Optical networking systems

Instruments requiring TEC temperature control

FUNCTIONAL BLOCK DIAGRAM

Figure 1.

GENERAL DESCRIPTION

The ADN88351 is a monolithic TEC controller with an integrated

TEC controller. It has a linear power stage, a pulse-width

modulation (PWM) power stage, and two zero-drift, rail-to-rail

chopper amplifiers. The linear controller works with the PWM

driver to control the internal power MOSFETs in an H bridge

configuration. By measuring the thermal sensor feedback

voltage and using the integrated operational amplifiers as a

proportional integral differential (PID) compensator to condition

the signal, the ADN8835 drives current through a TEC to settle

the temperature of a laser diode or a passive component attached

to the TEC module to the programmed target temperature.

The ADN8835 supports negative temperature coefficient

(NTC) thermistors as well as positive temperature coefficient

(PTC) resistive temperature detectors (RTDs). The target

temperature is set as an analog voltage input either from a

digital-to-analog converter (DAC) or from an external resistor

divider.

The temperature control loop of the ADN8835 is stabilized by

PID compensation utilizing the built in, zero-drift chopper

amplifiers. The internal 2.50 V reference voltage provides a 1%

accurate output that biases a thermistor temperature sensing

bridge as well as a voltage divider network to program the

maximum TEC current and voltage limits for both the heating and

cooling modes. With the zero-drift chopper amplifiers, excellent

long-term temperature stability is maintained via an autonomous

analog temperature control loop.

Table 1. TEC Family Models

Device No.

MOSFET

Thermal Loop

Package

ADN8831

Discrete

Digital/analog

LFCSP (CP-32-7)

ADN8833

Integrated

Digital

WLCSP (CB-25-7),

LFCSP (CP-24-15)

ADN8834

Integrated

Digital/analog

WLCSP (CB-25-7),

LFCSP (CP-24-15)

ADN8835

Integrated

Digital/analog

LFCSP (CP-36-5)

1

Product is covered by U.S. Patent No. 6,486,643.

TEC CURRENT

AND VOLTAGE

SENSE AND LIMIT

CONTROLLER

LINEAR

POWER

STAGE

TEC DRIVER

PWM

POWER

STAGE

OSCILLATOR

VOLTAGE

REFERENCE

OUT1

TMPGND

VLIM/

SD

VTEC

ILIM

PVINx

ITEC

EN/SY

VREF

LDR

ADN8835

SFB

IN2P

IN2N

IN1P

IN1N

OUT2

SW

PGNDx

VDD

AGND

ERROR

AMP

COMP

AMP