Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - power management - special purpose 50 mA TQFN 48 (7x7)

AVAILABLE

Functional Diagrams

Pin Configurations appear at end of data sheet.

Functional Diagrams continued at end of data sheet.

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ordering information, please contact Maxim Direct

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General Description

The MAX1978/MAX1979 are the smallest, safest, most

accurate complete single-chip temperature controllers for

Peltier thermoelectric cooler (TEC) modules. On-chip power

FETs and thermal control-loop circuitry minimize external

components while maintaining high efficiency. Selectable

500kHz/1MHz switching frequency and a unique ripple-can-

cellation scheme optimize component size and efficiency

while reducing noise. Switching speeds of internal

MOSFETs are optimized to reduce noise and EMI. An ultra-

low-drift chopper amplifier maintains ±0.001°C temperature

stability. Output current, rather than voltage, is directly con-

trolled to eliminate current surges. Individual heating and

cooling current and voltage limits provide the highest level of

TEC protection.

The MAX1978 operates from a single supply and provides

bipolar ±3A output by biasing the TEC between the outputs

of two synchronous buck regulators. True bipolar operation

controls temperature without “dead zones” or other nonlin-

earities at low load currents. The control system does not

hunt when the set point is very close to the natural operating

point, where only a small amount of heating or cooling is

needed. An analog control signal precisely sets the TEC

current. The MAX1979 provides unipolar output up to 6A.

A chopper-stabilized instrumentation amplifier and a high-

precision integrator amplifier are supplied to create a pro-

portional-integral (PI) or proportional-integral-derivative (PID)

controller. The instrumentation amplifier can interface to an

external NTC or PTC thermistor, thermocouple, or semicon-

ductor temperature sensor. Analog outputs are provided to

monitor TEC temperature and current. In addition, separate

overtemperature and undertemperature outputs indicate

when the TEC temperature is out of range. An on-chip volt-

age reference provides bias for a thermistor bridge.

The MAX1978/MAX1979 are available in a low-profile

48-lead thin QFN-EP package and is specified over the

-40°C to +85°C temperature range. The thermally

enhanced QFN-EP package with exposed metal pad

minimizes operating junction temperature. An evaluation

kit is available to speed designs.

Applications

Fiber Optic Laser Modules

WDM, DWDM Laser-Diode Temperature Control

Fiber Optic Network Equipment

EDFA Optical Amplifiers

Telecom Fiber Interfaces

ATE

Features

o Smallest, Safest, Most Accurate Complete

Single-Chip Controller

o On-Chip Power MOSFETS—No External FETs

o Circuit Footprint < 0.93in

o Circuit Height < 3mm

o Temperature Stability to 0.001°C

o Integrated Precision Integrator and Chopper

Stabilized Op Amps

o Accurate, Independent Heating and Cooling

Current Limits

o Eliminates Surges By Directly Controlling

TEC Current

o Adjustable Differential TEC Voltage Limit

o Low-Ripple and Low-Noise Design

o TEC Current Monitor

o Temperature Monitor

o Over- and Undertemperature Alarm

o Bipolar ±3A Output Current (MAX1978)

o Unipolar +6A Output Current (MAX1979)

Integrated Temperature

Controllers for Peltier Modules

Ordering Information

FREQ

N.C

LX1

PGND1

N.C.

LX1

GND

LX1

PGND1

PGND2

LX2

PGND2

LX2

N.C.

LX2

N.C.

OS2

DIFOUT

FB-

FB+

BFB+

AOUT

AIN-

AIN+

GND

INT-

INTOUT

REF

CTLI

GND

MAXV

MAXIN

MAXIP

ITEC

COMP

OS1

TQFN-EP

MAX1978

MAX1979

BFB-

TOP VIEW

*ELECTRICALLY CONNECTED TO THE UNDERSIDE METAL SLUG.

NOTE: GND IS CONNECTED TO THE UNDERSIDE METAL SLUG.

SHDN

Pin Configuration

Typical Operating Circuit appears at end of data sheet.

PART T EM P R A N G E PIN-PACKAGE

MAX1978ETM+ - 40°C to + 85°C 48 Thin QFN-EP*

MAX1979ETM+ - 40°C to + 85°C 48 Thin QFN-EP*

EP = Exposed pad.

Denotes a lead(Pb)-free/RoHS-compliant package.

Pin Configuration

19-2490; Rev 3; 3/10

Typical Operating Circuit appears at end of data sheet.

MAX1978/MAX1979

Summary of content (20 pages)

PAGE 1
MAX1978/MAX1979 LE AVAILAB Integrated Temperature Controllers for Peltier Modules General Description MAXIP COMP ITEC 39 37 38 MAXV MAXIN 41 40 GND GND 43 42 CTLI VDD 45 44 CS REF 47 46 OS1 48 + 36 OS2 N.C. PGND2 LX2 PGND2 LX2 1 PVDD2 7 N.C. LX2 PVDD2 SHDN 8 29 9 28 10 27 11 26 12 25 35 3 34 4 33 32 5 6 31 FREQ N.C PGND1 LX1 PGND1 LX1 PVDD1 N.C.
PAGE 2
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules ABSOLUTE MAXIMUM RATINGS Peak LX Current (MAX1978) (Note 1).................................±4.5A Peak LX Current (MAX1979) (Note 1)....................................+9A Continuous Power Dissipation (TA = +70°C) 48-Lead Thin QFN-EP (derate 26.3mW/°C above +70°C) (Note 2) .................2.105W Operating Temperature Ranges MAX1978ETM ..................................................-40°C to +85°C MAX1979ETM ...........................
PAGE 3
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules ELECTRICAL CHARACTERISTICS (continued) (VDD = PVDD1 = PVDD2 = V SHDN = 5V, FREQ = GND, CTLI = FB+ = FB- = MAXV = MAXIP = MAXIN = REF, TA = 0°C to +85°C, unless otherwise noted. Typical values at TA = +25°C.) PARAMETER PFET Leakage No-Load Supply Current Shutdown Supply Current Thermal Shutdown SYMBOL TYP MAX VLX = 0, TA = +25°C 0.02 10 VLX = 0, TA = +85°C 1 IDD(NO VDD = 5V 30 50 LOAD) VDD = 3.
PAGE 4
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules ELECTRICAL CHARACTERISTICS (continued) (VDD = PVDD1 = PVDD2 = V SHDN = 5V, FREQ = GND, CTLI = FB+ = FB- = MAXV = MAXIP = MAXIN = REF, TA = 0°C to +85°C, unless otherwise noted. Typical values at TA = +25°C.) PARAMETER Integrator Amp Open-Loop Gain SYMBOL AOL-INT MIN RLOAD = 10kΩ to REF TYP MAX 120 UNITS dB Integrator Amp CMRR CMRRINT Integrator Amp Input Bias Current IINT-BIAS VDD = 3V to 5.
PAGE 5
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules ELECTRICAL CHARACTERISTICS (VDD = PVDD1 = PVDD2 = V SHDN = 5V, FREQ = GND, CTLI = FB+ = FB- = MAXV = MAXIP = MAXIN = REF, TA = -40°C to +85°C, unless otherwise noted.
PAGE 6
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules ELECTRICAL CHARACTERISTICS (continued) (VDD = PVDD1 = PVDD2 = V SHDN = 5V, FREQ = GND, CTLI = FB+ = FB- = MAXV = MAXIP = MAXIN = REF, TA = -40°C to +85°C, unless otherwise noted.) (Note 5) PARAMETER SYMBOL CONDITIONS MIN MAX VMAXV = VREF 0.67, VOS1 to VOS2 = ±4V, VDD = 5V -1 +1 VMAXV = VREF ✕ 0.33, VOS1 to VOS2 = ±2V, VDD = 3V -2 +2 -0.1 +0.1 µA 10.
PAGE 7
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules Typical Operating Characteristics (VDD = 5V, VCTLI = 1V, VFREQ = GND, RTEC = 1Ω, circuit of Figure 1, TA = +25°C, unless otherwise noted.) EFFICIENCY vs. TEC CURRENT VDD = 3.3V 70 MAX1978 toc02 80 70 60 EFFICIENCY (%) 60 50 40 30 50 VOS1 100mV/div AC-COUPLED 40 30 20 20 VOS1 - VOS1 50mV/div RTEC = 0.855Ω RTEC = 1.1Ω 10 10 VOS2 100mV/div AC-COUPLED 0 0 0.5 1.0 1.5 2.0 0 2.5 0.5 1.0 1.5 2.5 2.
PAGE 8
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules Typical Operating Characteristics (continued) (VDD = 5V, VCTLI = 1V, VFREQ = GND, RTEC = 1Ω, circuit of Figure 1, TA = +25°C, unless otherwise noted.) SWITCHING FREQUENCY CHANGE vs. INPUT SUPPLY -5 -10 -15 -20 -25 -30 0 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0 -35 3.5 3.0 4.0 4.5 5.0 MAX1978 toc12 1 0 -1 -2 -3 -4 3.0 5.5 2 3.5 4.0 4.5 5.0 5.
PAGE 9
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules Typical Operating Characteristics (continued) (VDD = 5V, VCTLI = 1V, VFREQ = GND, RTEC = 1Ω, circuit of Figure 1, TA = +25°C, unless otherwise noted.) THERMAL STABILITY, HEATING MODE TTEC = +25°C TA = +5°C ITEC = +25°C TA = +25°C MAX1978 toc21 0.03 0.02 TEMPERATURE ERROR (°C) MAX1978 toc19 TEMPERATURE 0.001°C/div MPERATURE 0.001°C/div TEMPERATURE ERROR vs. AMBIENT TEMPERATURE MAX1978 toc20 THERMAL STABILITY, ROOM TEMPERATURE 0.
PAGE 10
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules Pin Description (continued) PIN NAME 23 AIN- 24 AOUT Undedicated Chopper-Stabilized Amplifier Output 27, 30 PVDD1 Power 1 Inputs. Must be same voltage as VDD. Connect all PVDD1 inputs together at the VDD power plane. Bypass to PGND1 with a 10µF ceramic capacitor. 28, 31, 33 LX1 Inductor 1 Connection. Connect all LX1 pins together. Connect LX1 to LX2 when using the MAX1979. Power Ground 1.
PAGE 11
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules Functional Diagram ON OFF SHDN FREQ VDD REF 1.5V REFERENCE MAXV PVDD1 MAX VTEC = VMAXV x 4 MAXIP 3V TO 5.5V LX1 MAX ITEC = (VMAXIP/ VREF) x (0.15V/RSENSE) MAX ITEC = (VMAXIN/ VREF) x (0.
PAGE 12
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules Detailed Description TEC temperature. The on-chip thermal-control circuitry can be configured to achieve temperature control stability of 0.001°C. Figure 1 shows a typical TEC thermalcontrol circuit. Power Stage The power stage of the MAX1978/MAX1979 thermoelectric cooler (TEC) temperature controllers consists of two switching buck regulators that operate together to directly control TEC current.
PAGE 13
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules Switching Frequency FREQ sets the switching frequency of the internal oscillator. The oscillator frequency is 500kHz when FREQ = GND. The oscillator frequency is 1MHz when FREQ = VDD. The 1MHz setting allows minimum inductor and filter-capacitor values. Efficiency is optimized with the 500kHz setting. Voltage and Current-Limit Settings The MAX1978 and MAX1979 provide settings to limit the maximum differential TEC voltage.
PAGE 14
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules VDD REF 10µF 10µF 1µF 10µF 0.01µF VDD SHDN PVDD1 PVDD2 COMP UNDERTEMP ALARM OVERTEMP ALARM DC CURRENT MONITOR UT REF MAXV MAXIN MAXIP LX1 LX2 CS 3µH 1µF OT 0.03Ω ITEC OS1 20kΩ 1% MAX1979 4.7µF BFB80.6kΩ 1µF THERMISTOR VOLTAGE MONITOR AIN- TEC OS2 AOUT AIN+ REF 69.8kΩ 1% 105kΩ 1% CTLI FREQ GND FB- REF THERMAL FEEDBACK FB+ PGND2 PGND1 INTOUT INT- DIFOUT 10kΩ 100kΩ 10µF 0.047µF 0.
PAGE 15
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules 22µF to 100µF ceramic capacitor between the V DD power plane and power ground. Insufficient supply bypassing can result in supply bounce and degraded accuracy. REF 69.8kΩ 1% Compensation Capacitor Include a compensation capacitor to ensure currentpower control-loop stability.
PAGE 16
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules The MAX1979 controls the TEC current in only one direction (unipolar). Set the maximum unipolar TEC current by applying a voltage to MAXIP. Connect MAXIN to MAXIP when using the MAX1979. The equation for setting MAXIP is the same for the MAX1978 and MAX1979. Do not exceed the positive or negative current-limit specifications on the TEC. Refer to the TEC manufacturer’s data sheet for these limits.
PAGE 17
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules Shutdown Control Drive SHDN low to place the MAX1978/MAX1979 in a power-saving shutdown mode. When the MAX1978/ MAX1979 are in shutdown, the TEC is off (VOS1 and VOS2 decay to GND) and input supply current lowers to 2mA (typ). ITEC Output ITEC is a status output that provides a voltage proportional to the actual TEC current. ITEC = REF when TEC current is zero. The transfer function for the ITEC output: VITEC = 1.
PAGE 18
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules where: A = The gain needed to move the 0dB crossover point up to the desired frequency. In this case, A = -4dB = 0.6. fC = The desired crossover frequency, 1.5Hz in this example. C1 is found to be 0.58µF; use 0.47µF. Next, the second TEC pole must be cancelled by adding a zero. Canceling the second TEC pole provides maximum phase margin by adding positive phase to the circuit.
PAGE 19
MAX1978/MAX1979 Integrated Temperature Controllers for Peltier Modules Typical Operating Circuit INPUT 3V TO 5.
PAGE 20
MAX1978/MAX1979 Integrated Temperature Controller for Peltier Modules Revision History REVISION NUMBER REVISION DATE DESCRIPTION PAGES CHANGED 0 7/02 Initial release 1 2/07 Updated the Ordering Information, Pin Description, and Package Information. — 2 1/10 Revised the Pin Description and the Setting Max Positive and Negative TEC Current section. 10, 16 3 3/10 Revised the Figure 1 and 2 captions, and the Voltage and Current-Limit Settings section.