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19-3517; Rev 0; 11/04
MAX8521 Evaluation Kit
General Description
The MAX8521 evaluation kit (EV kit) is an assembled and tested PC board that implements a switch-mode driver for a Peltier thermoelectric cooler (TEC) module. The device operates from a single 3V to 5.5V supply and provides a bipolar 1.5A output to the module. A potentiometer, DAC, or external source generates a DC temperature set-point voltage. Thermal feedback from the TEC module is compared to the set-point voltage to generate the TEC current control signal. The MAX8521 accurately regulates the TEC current based on this signal. When using the DAC, the EV kit connects to the parallel port of a computer running Windows(R) 95, 98, or 2000. Software, included with the EV kit, provides a quick and easy method to control the DAC. To evaluate the MAX8520ETP or MAX8521ETP (QFN version), refer to the MAX8520 evaluation kit. Note: Windows 2000 requires the installation of a driver located on the CD. Circuit Footprint Less than 0.31in2 Operates from a Single Supply (3V to 5.5V) 1.5A Output Current High-Efficiency Switch-Mode Design Programmable Heating/Cooling Current Limit TEC Current Monitor Output 500kHz or 1MHz Switching Frequency SPITM-Compatible Serial Interface Easy-to-Use Menu-Driven Software Includes Windows 95/98/2000-Compatible Software and Demo PC Board Surface-Mount Construction Fully Assembled and Tested
Features
Evaluates: MAX8521
UCSP is a trademark of Maxim Integrated Products, Inc. Windows is a registered trademark of Microsoft Corp. SPI is a trademark of Motorola, Inc.
PART MAX8521EVKIT
Ordering Information
TEMP RANGE 0C to +70C IC PACKAGE 36 UCSPTM
Component List
DESIGNATION C1, C2, C3, C5, C11, C20 QTY DESCRIPTION 1F 10%, 6.3V X5R (0603) ceramic capacitors Murata GRM188R60J105K Taiyo Yuden JMK107BJ105KA 10F 20%, 6.3V X5R (0805) ceramic capacitors Taiyo Yuden JMK212BJ106MG 0.1F 10%, 25V X5R (0603) ceramic capacitors Murata GRM188R71E104K Taiyo Yuden TMK107BJ104KA 0.047F 10%, 10V X7R (0402) ceramic capacitor Murata GRP155R71A473K Not installed (1206) Not installed (0603) 0.022F 10%, 50V X7R (0603) ceramic capacitor Murata GRM188R71H223K DESIGNATION C18 QTY 1 DESCRIPTION 10F 20%, 4V X5R (0603) ceramic capacitor TDK C1608X5R0G106M 150F 20%, 6.3V, 18m ESR, 2.8A, D2E size, POSCAP Sanyo 6TPE150MI DB25 male right-angle connector 2-pin header Not installed 3-pin headers 2.2H, 1.6A inductors Sumida CDRH2D18/HP-2R2 npn bipolar transistors, 40V, SOT23 Central Semiconductor CMPT3904 0.1 1%, 0.25W (1206) sense resistor Panasonic ERJ8RSFR10 47k 5% (0402) resistor 100k 1% (0402) resistor
6
C21 J1 J2 J3-J6 J7, J8 L1, L2 Q1, Q2, Q3 R1 R3 R4
1 1 1 0 2 2 3 1 1 1
C4, C10, C16
3
C6, C7, C12, C13, C14
5
C8 C9 C15 C17
1 0 0 1
________________________________________________________________ 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.
MAX8521 Evaluation Kit Evaluates: MAX8521
Component List (continued)
DESIGNATION R5-R8, R24 R9, R10, R11 R12-R15, R18 R16 R17 R19 R20 QTY 0 3 5 1 1 1 1 DESCRIPTION Not installed (0402) 4.7k 5% (0603) resistors 1k 5% (0603) resistors 240k 5% (0603) resistor 47k 1%, (0603) resistor 10 5% (0603) resistor 10k 0.1%, 25ppm/C (0805) resistor Panasonic ERA6YEB103 U2 U3 U4 1 0 1 DESIGNATION R21, R22 R23 SW1 U1 QTY 0 1 1 1 DESCRIPTION Not installed (0603) 10k potentiometer (multiturn) Switch, momentary, NO Power driver, 36-pin UCSP MAX8521EBX Op amp, SOT23-6 MAX4238AUT-T Not installed, SO-8 Serial, 14-bit DAC, 10-pin MAX(R) MAX5144EUB
Component Suppliers
SUPPLIER Central Semiconductor Murata Panasonic Sanyo Sumida Taiyo Yuden TDK PHONE 631-435-1110 770-436-1300 714-373-7366 619-661-6835 847-545-6700 800-348-2496 847-803-6100 FAX 631-435-1824 770-436-3030 714-737-7323 619-661-1055 847-545-6720 847-925-0899 847-390-4405 www.murata.com www.panasonic.com www.sanyodevice.com www.sumida.com www.t-yuden.com www.component.tdk.com WEBSITE www.centralsemi.com
Note: Indicate you are using the MAX8521 when contacting these manufacturers.
Quick Start
Required Equipment
The following equipment is required before beginning: * A DC power supply capable of supplying any voltage between 3V and 5.5V at 1.5A A Peltier TEC module with a thermistor (NTC, 10k at +25C) * A digital voltmeter (DVM) The MAX8521 EV kit is a fully assembled and tested surface-mount board. Follow the steps below to verify board operation. Do not turn on the power supply until all connections are completed: 1) Place a shunt across J2 to connect the thermal loop to CTLI. 2) Place a shunt across pins 1 and 2 on J8 to select the potentiometer. 3) Place a shunt across pins 2 and 3 on J7 to disable the MAX8521 output. *
4)
5)
Obtain TEC module specifications for absolute maximum TEC voltage and absolute maximum current. Set these (or lower) limits at the MAX8521's MAXV, MAXIP, and MAXIN inputs. See Tables 1, 2, and 3 to select resistors or refer to the MAX8520/MAX8521 data sheet. Connect the TEC module to OS1, OS2, THERM, and GND. Typical connections for most modules are: a) Module TEC- to OS2 b) Module TEC+ to OS1 c) Module thermistor to THERM d) 2nd module thermistor pin to GND e) Module case ground or shield to GND Be sure to check your module specifications before making connections. Also, it is recommended that the thermistor be connected by shielded wire for lowest noise.
6) 7)
MAX is a registered trademark of Maxim Integrated Products, Inc. 2 _______________________________________________________________________________________
Connect the DVM to SET-POINT IN and GND. Connect a 3.3V or 5V DC power supply with sufficient power rating to VDD and GND.
MAX8521 Evaluation Kit
8) 9) 10) Turn on the power supply. Note: The MAX8521 output is not enabled yet. Adjust R23 until the DVM reads 0.75V. This adjusts the set point for approximately +25C. Move the DVM positive lead to THERM and verify a voltage of approximately 0.75V. This represents ambient temperature at the TEC module. Enable the MAX8521 by moving the shunt on J7 to the 1 and 2 position. After enabling the MAX8521, verify that the THERM voltage converges toward the set-point voltage on R23 (set to 0.75V in step 9) after approximately 30 seconds. The easiest way to measure the convergence is to place a DVM between THERM and SET-POINT. The voltage should read less than 100V. If the TEC is connected backwards, the THERM voltage will move away from 0.75V toward either 0V or 1.5V. If this occurs, shut down the MAX8521 and reverse the TEC+ and TEC- connections. Once proper operation is verified, other temperatures can be set with R23, the DAC, or an external voltage applied to SET-POINT IN. (1V is approximately +10C; 0.5V is approximately +40C. The slope is approximately -14mV/C for a typical NTC thermistor.)
Evaluates: MAX8521
Voltage on MAXIP : VMAXIP (V) = REF x
R6 R5 + R6 R8 Voltage on MAXIN : VMAXIN (V) = REF x R7 + R8
11) 12)
Resistor values for R2 through R7 should be between 10k and 100k. positive TEC current:A) = + VMAXIP I (
TECP(MAX)
10 x RSENSE
where RSENSE (R1) is 100m. Maximum negative TEC current: ITECN(MAX) (A) =
-
VMAXIN 10 x RSENSE
13)
The components installed on the MAX8521 EV kit set the maximum positive current to +1.5A and the maximum negative current to -1.5A. See Tables 2 and 3 or refer to the MAX8520/MAX8521 data sheet for more information.
Jumper J2
Jumper J2 connects the current control input (CTLI) of the MAX8521 to the error signal of the thermal loop. The thermal-loop circuit compares thermistor feedback from the TEC module to the set-point voltage to generate the CTLI signal. To drive CTLI directly, remove the shunt on J2 and apply a DC voltage between 0 and 3V to the CTLI pad. A 1.5V voltage on CTLI sets a TEC current of approximately 0A. A voltage of 0V or 3V on CTLI produces 1.5A or +1.5A, respectively. The current changes proportionally with the voltage applied to CTLI. Note: The current will not reach 1.5A if the maximum positive and negative current limits are set to lower values. Refer to the Voltage and Current-Limit Settings section in the MAX8520/MAX8521 data sheet for more information.
Detailed Description
Voltage and Current-Limit Settings
The MAX8521 provides control of the maximum differential TEC voltage and the maximum positive and negative TEC current. The voltage on the MAXV pin of the MAX8521 sets the maximum differential TEC voltage. Use the following equations to set the voltage: Voltage on MAXV : VMAXV (V) = REF x R4 R3 + R4
Maximum TEC voltage : VTEC(MAX) = 4 x VMAXV The components installed on the MAX8521 EV kit set VMAXV to 1V, for a maximum TEC voltage of 4V. See Table 1 or refer to the MAX8520/MAX8521 data sheet for more information. The voltages on the MAXIP and MAXIN pins set the maximum positive and negative current through the TEC. Use the following equations to set the currents:
Jumper J6
Jumper J6 sets the switching frequency for the MAX8521. Position 1-2 sets the frequency to 1MHz. Position 2-3 sets it to 500kHz. Note: The MAX8521 is shipped with a short across pins 1 and 2 of J6.
Jumper J7
The MAX8521 can be placed in shutdown mode using jumper J7. See Table 4 for jumper settings.
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3
MAX8521 Evaluation Kit Evaluates: MAX8521
Jumper J8
Jumper J8, position 2-3, connects the DAC to the thermal-loop circuit. Connect the EV kit to the parallel port of a computer and use the EV kit software to control the DAC. Position 1-2 connects potentiometer R23 to the thermal-loop circuit. To use an external voltage to control the thermal loop, remove the shunt from J8 and apply the voltage to the SET-POINT IN pad. A voltage of +0.75V corresponds to approximately +25C. 1V is approximately +10C, and 0.5V is approximately +40C. The slope is approximately -14mV/C for a typical NTC thermistor.
Table 1. Maximum TEC Voltage
VTEC(MAX) 4V 2.6V R3 47k 130k R4 100k 100k
Table 2. Maximum Positive TEC Current
ITECP(MAX) 1.5A 0.75A 0.5A R5 Short 100k 100k R6 Open 100k 49.9k
Switch SW1
Switch SW1 resets the DAC to 0.75V.
Table 3. Maximum Negative TEC Current
ITECN(MAX) 1.5A 0.75A 0.5A R7 Short 100k 100k R8 Open 100k 49.9k
ITEC Current-Monitor Output
The ITEC output provides a voltage proportional to the actual TEC current. VITEC = REF when the TEC current is zero. The actual TEC current is: ITEC = VITEC -1.5V 8 x R1
Use ITEC to monitor the cooling or heating current through the TEC module. Positive values of ITEC indicate heating for typically connected modules. For stability, keep the ITEC output capacitance below 150pF.
Table 4. Jumper Selection
JUMPER J7 JUMPER POSITION 1-2 2-3* 1-2* J6 2-3 MAX8521 switching frequency is 500kHz. Drive the CTLI pad directly with a DC voltage. Disconnects the thermal-loop circuit. Thermal-control loop is closed. DAC or R23 generates temperature set point. DAC generates temperature set point. Potentiometer R23 generates temperature set point. Voltage applied to SET-POINT IN generates temperature set point. FUNCTION SHDN = High. MAX8521 enabled. SHDN = Low. MAX8521 disabled. MAX8521 switching frequency is 1MHz.
Controlling TEC Through a Parallel Port
Required Equipment
In addition to the equipment listed under the Quick Start section, you will need the following: * A computer running Windows 95, 98, or 2000 (Note: Windows 2000 requires the installation of a driver located on the CD.) * A parallel printer port (DB25 on the back of the computer) * A standard 25-pin, straight-through, male-tofemale cable (printer extension cable) to connect the computer's parallel port to the MAX8521 EV kit
Open J2 Closed* 1-2 J8 2-3* Open
Procedure
1) 2) 3) Place a shunt across J2 to connect the thermal loop to CTLI. Place a shunt across pins 2 and 3 on J8 to select the DAC. Place a shunt across pins 2 and 3 on J7 to disable the MAX8521 output.
*Default position.
4
_______________________________________________________________________________________
MAX8521 Evaluation Kit
4) Obtain TEC module specifications for absolute maximum TEC voltage and absolute maximum current. Set these (or lower) limits at the MAX8521 MAXV, MAXIP, and MAXIN inputs. See Tables 1, 2, and 3 to select resistors or refer to the MAX8521 data sheet. Connect the TEC module to OS1, OS2, THERM, and GND. Typical connections for most modules are: a) Module TEC- to OS2 b) Module TEC+ to OS1 c) Module thermistor to THERM d) 2nd module thermistor pin to GND e) Module case ground or shield to GND Be sure to check your module specifications before making connections. Also, it is recommended that the thermistor be connected through shielded wire for lowest noise. Connect a cable from the computer's parallel port to the MAX8521 EV kit. Use a straight-through, 25pin female-to-male cable. To avoid damaging the EV kit or your computer, do not use a 25-pin SCSI port or any other connector that is physically similar to the 25-pin parallel printer port. 1.5V. If this occurs, shut down the MAX8521 and reverse the TEC+ and TEC- connections. 14) Once proper operation is verified, other temperatures can be set with the DAC. See the Software User Interface section.
Evaluates: MAX8521
5)
Software User Interface
The user interface is easy to operate using either the mouse or the Tab key to navigate. To program the DAC, enter the ratio of the desired DAC output voltage (VDAC) to the reference voltage (REF): V ratio = DAC , where REF = +1.5V REF The ratio must be a decimal number between 0 and 1. Press Enter or click on the Update button to send the data to the DAC. The program starts with a ratio of 0.5. This sets the DAC output to 0.75V, which corresponds to +25C. A ratio of 0.67 sets the DAC output to 1V, which corresponds to approximately +10C. A ratio of 0.33 sets the DAC output to 0.5V or approximately +40C. The slope is approximately -14mV/C for a typical NTC thermistor.
6)
General-Purpose SPI Utility
There are two methods for communicating with the MAX5144 DAC: through the user-interface panel or through the general-purpose SPI utility. This utility (Figure 3) configures SPI parameters such as clock polarity (CPOL), clock phase (CPHA), and chip-select (CS) polarity. The fields where pin numbers are required apply to the pins of the parallel port connector. The utility handles the data only in byte (8-bit) format. Data longer than a byte must be handled as multiple bytes. For example, a 16-bit word should be broken into two 8-bit bytes. To write data to the slave device, enter the data into the field labeled "Data bytes to be written." Each data byte should be hexadecimal, prefixed by 0x, and separated with a comma. Press the Send Now button to write the data to the slave. To read data from the slave device, the field "Data bytes to be written:" must contain hexadecimal values. Include the same number of bytes as to be read from the slave. Note: The MAX5144 is a write-only device and cannot be read.
7)
Install the software by running the INSTALL.EXE program. The install program copies the files and creates icons for them in the Windows 95/98/2000 Start menu. Click on the UNINSTALL icon to remove the EV kit software from the hard drive. 8) Connect a 3.3V or 5V DC power supply with sufficient power rating to VDD and GND. 9) Turn on the power supply. 10) Start the MAX8521 program by opening its icon in the Start menu. At program startup, the software forces the DAC to 0.75V, which corresponds to approximately +25C. 11) Connect the DVM to THERM and verify a voltage of approximately 0.75V. This represents ambient temperature at the TEC module. 12) Enable the MAX8521 by moving the shunt on JU1 to the 1-2 position. 13) After enabling the MAX8521, verify that the THERM voltage converges toward the DAC voltage (0.75V) after approximately 30 seconds. The easiest way to measure the convergence is to place a DVM between THERM and SET-POINT. The voltage should read less than 100V. If the TEC is connected backwards, the THERM voltage will move away from 0.75V toward either 0V or
_______________________________________________________________________________________
5
MAX8521 Evaluation Kit Evaluates: MAX8521
1.5V REF SET-POINT IN DAC 10F 50k JU8 1.5V REF 240k 10F CTLI 1k 0.022F
OS1 10k JU2 1.5V REF THERM 10k 0.1F MAX8521 OS2
TECP
TEC+ N
10k THERMISTOR
GND THERMAL LINK
Figure 1. Thermal-Loop Functional Diagram for the MAX8521 EV Kit
Figure 2. Main Window for the MAX8521 EV Kit 6 _______________________________________________________________________________________
MAX8521 Evaluation Kit Evaluates: MAX8521
Figure 3. SPI Utility Showing the Settings to Communicate with the MAX8521 EV Kit
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7
Evaluates: MAX8521
B3 N.C. B4 N.C. E3 N.C. E4 N.C.
B2 GND2 B5 GND2 C3 GND2 C4
GND2
MAX8521 Evaluation Kit
MAXV
MAXIP
MAXIN
Figure 4. MAX8521 EV Kit Schematic
VDD LX1 E2 LX1 F4 CS C3 1F VDD VDD1 R19 10 VDD1 CS R1 0.1 TP1 OS1 F3 OS1 U3B_OUT THERM VREF C15 OPEN U3A MAX4477 OPEN 1 J4 4 1 2 3 J5 1 2 3 R21 OPEN 2 R17 47k + U3A N 3 THERM THERM C6 0.1F TP8 GND THERM C4 10F SHDN TP2 CTLI OS2 LX2 C20 1F U2 R24 VDD OPEN J6 1 2 3 CTLI TP3 CTLI SHDN GND VREF ITEC C8 0.047F 2 1 CS REF CS 1 2 3 OUT 6 OUT C14 0.1F VDD J8 U3A TP9 IN TP10 GND SW1 TP13 DIN 4 1 2 3 DIN R14 1k DIN CLR INV RFB GND 5 7 8 10 CLRR15 1k VDD P 5 6 + 1 9 VDD TP11 1 2 3 CSR12 1k C12 0.1F C13 0.1F MAXV A3 A2 VREF VREF X_CS Q1 R5 SHORT R10 4.7k R6 OPEN SCLK Q2 1 R13 1k R8 OPEN X_SCLK TP12 VDD R7 SHORT A1 R9 4.7k MAXIP MAXIN COMP C2 VDD1 C17 0.022F VREF 3 R23 10k R22 OPEN A6 CTLI A5 C16 10F C18 10F R16 240k R18 1k U2 I 0 56 3 SHDN+ 1 VCC GND 4 2 VDD VSS L2 2.2H J2 U2 MAX4238 OS2 PVDD2 PVDD2 LX2 LX2 E6 E5 C6 OS2 1 2 3 OS1 C11 1F J3 E1 LX1 L1 2.2H
9
8 7
4
6 5
3 2 1
25
24 23
22 21
20
19 18 17
16 15
14 13
12
11 10
8
U1 MAX8521_UCSP
R20 10k TP7 REF FREQ C5 FREQ VCC U3B GND 7
C1 1F
VDD
B6
VDD
C2 1F
F1 PVDD1 F2 PVDD1
D1
PGND1 D2 PGND1 D3 PGND1
VDD
F5
C5 1F
F6
D4
PGND2 D5 PGND2 D6 PGND2
VREF
A4
C7 0.1F
C1
SHDN
VDD
J7
1 2 3
B1
ITEC
TP4
ITEC
VREF
R3 47k
U4 MAX5144
3 SCLK
R4 100k 2 3 SCLK
MAX4477 OPEN
U3B_OUT
TP5 X_DIN Q3
VDD R11 4.7k
VDD
VDD
TP6
C9 OPEN
C10 10F
C21 150F
GND
X_DIN X_CS X_SCLK
_______________________________________________________________________________________
XXX XX X XXXX X J1
MAX8521 Evaluation Kit Evaluates: MAX8521
1.0"
Figure 5. MAX8521 EV Kit Component Placement Guide--Component Side
1.0"
Figure 6. MAX8521 EV Kit PC Board Layout--Component Side
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9
MAX8521 Evaluation Kit Evaluates: MAX8521
1.0"
Figure 7. MAX8521 EV Kit PC Board Layout--Layer 2
1.0"
Figure 8. MAX8521 EV Kit PC Board Layout--Layer 3
10
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MAX8521 Evaluation Kit Evaluates: MAX8521
1.0"
Figure 9. MAX8521 EV Kit PC Board Layout--Solder Side
1.0"
Figure 10. MAX8521 EV Kit Component Placement Guide--Solder Side
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 11 (c) 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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