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19-2147; Rev 0; 8/01
MAX6902 Evaluation System/Evaluation Kit
General Description
The MAX6902 evaluation system (EV system) consists of a MAX6902 evaluation kit (EV kit) and a companion Maxim SMBusTM interface board. The MAX6902 EV kit is an assembled and tested PC board that demonstrates the MAX6902 SPITM bus realtime clock (RTC). This EV kit is intended to demonstrate the functionality and features of the MAX6902 RTC. It is not designed to exercise the MAX6902 at its maximum SPI bus interface speed. A typical bus interface speed is in the 90kHz range and depends upon the operating system and computer used. The Maxim SMBus interface board (MAXSMbus) allows an IBM-compatible PC to use its parallel port to emulate the SPI, 3-wire, and SMBus (2-wire) interfaces. Windows 95/98(R)-compatible software provides a userfriendly interface to exercise the features of the MAX6902. (Note: Windows NT/2000 requires additional driver software; contact factory.) The program is menu driven and offers a graphic interface with control buttons and status display. Order the complete EV system (MAX6902EVSYS) for comprehensive evaluation of the MAX6902 using a PC. Order the EV kit (MAX6902EVKIT) if the MAXSMbus module has already been purchased with a previous Maxim EV system, or for custom use in other C-based systems. o Proven PC Board Layout o Low-Voltage Operation o Supply Current Monitoring o Fully Assembled and Tested o Easy-to-Use Menu-Driven Software o Includes: Windows 95/98-Compatible Software (3.5in Floppy Disk) and Demo PC Board
Features
Evaluates: MAX6902
Ordering Information
PART MAX6902EVKIT MAX6902EVSYS TEMP. RANGE 0C to +70C 0C to +70C INTERFACE TYPE User supplied MAXSMBus
Note: The MAX6902 EV kit software is provided with the MAX6902EVKIT. However, to use the software, the MAXSMbus board is required to interface the EV kit to the computer.
MAX6902EVKIT Component List
DESIGNATION QTY DESCRIPTION 0.1F, 16V X7R ceramic capacitors (0603) Taiyo Yuden EMK107BJ104KA or Murata GRM39X7R104K016 or TDK C1608X7R1C104K 10F, 35V capacitors Al Electrolytic 2 10 right-angle female receptacle 2-pin headers Not installed 49.9k 1% resistor Y1 1 DESIGNATION R2 U1 U2 U3 U4 QTY 1 1 1 1 1 DESCRIPTION 470k 5% resistor MAX6902EKA (8-pin SOT23) RTC MAX1840EUB (10-pin MAX) level translator MAX3370EXK (SC70) level translator MAX1615EUK (5-pin SOT23) linear voltage regulator 32.768kHz quartz crystal, 12.5pF, 20ppm ECS, Inc. ECS-3X8 FOX Electronics NC38 Vishay Dale XT38T Not installed
C1, C2, C3, C6
4
C4, C5 J1 JU1, JU2 JU3-JU7 R1
2 1 2 0 1
SMBus is a trademark of Intel Corp. SPI is a trademark of Motorola, Inc. Windows is a registered trademark of Microsoft Corp.
Y2
0
________________________________________________________________ Maxim Integrated Products
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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.
MAX6902 Evaluation System/Evaluation Kit Evaluates: MAX6902
MAX6902EVSYS Component List
PART MAX6902EVKIT MAXSMBUS QTY 1 1 DESCRIPTION MAX6902 evaluation kit Interface board
6) Start the program by opening its icon in the Start menu. 7) Click on the Set from computer's clock button to write the current time of day into the MAX6902. 8) Observe the difference between the computer's time and the MAX6902 time. The offset is calculated by Offset = RTC time - PC time. In general, the RTC keeps more accurate time than the PC. To determine long-term accuracy of the RTC, it must be set by and checked against an accurate time source. The easiest way to do this using the MAX6902 evaluation software is to use an Internet time service to set the PC clock and then set the RTC from the PC clock. This Internet time service can then be used to update accurately the PC clock regularly for an accurate comparison of the RTC against a known time standard. The National Institute of Standards and Technology (NIST) offers such an Internet time service without charge (see www.boulder.nist.gov/ timefreq/service/its.htm). Note: The MAX6902EVSYS may be unplugged from the parallel port for long-term drift testing.
Component Suppliers
SUPPLIER Murata Taiyo Yuden TDK PHONE 770-436-1300 800-348-2496 847-803-6100 FAX 770-436-3030 847-925-0899 847-390-4405
Note: Please indicate you are using the MAX6902 when contacting these manufacturers.
Quick Start
Required Equipment
Before you begin, the following equipment is needed: * Maxim MAX6902EVKIT and MAXSMbus interface board * * * * 12VDC power supply (any supply voltage between +9V and +15V is acceptable) Computer running Windows 95 or 98 Spare parallel port 25-pin I/O extension cable
Detailed Description of Hardware
The MAX6902 (U1) is a real-time clock with RAM. The two level translators, MAX1840 (U2) and MAX3370 (U3), are not required for normal operation of the MAX6902, but allow operation at supply voltages down to +2V, while still communicating with the MAXSMbus board, which is using +5V logic levels. See Figure 7 and refer to the MAX6902 data sheet.
Procedure
1) Carefully connect the boards by aligning the 20-pin connector of the MAX6902 EV kit with the 20-pin header of the MAXSMbus interface board. Gently press them together. The two boards should be flush against each other. Do not turn on the power until all connections are made. 2) Connect the 25-pin I/O extension cable from the computer's parallel port to the MAXSMbus board. The EV kit software uses a loopback connection to confirm that the correct port has been selected. 3) Install the EV system software on your computer by running the INSTALL.EXE program on the floppy disk. The program files are copied and icons are created for them in the Windows Start menu. 4) Ensure that the jumper settings are in the default position (Table 1). 5) Connect the 12VDC power supply to the MAXSMbus board between POS9 and GND. Voltage for the MAX6902 ICs comes from the MAXSMbus board.
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Measuring Timekeeping Supply Current
The MAX6902 is in standby mode whenever no commands are being sent. To measure the timekeeping supply current drawn in standby mode, first ensure that the main screen's Cyclic Burst Read checkbox is not checked, remove the shunt from jumper JU2, and measure the voltage across resistor R1. A voltage drop of 10mV represents 200nA of timekeeping supply current. For active bus operation (serial bus activity), replace shunt JU2 to prevent excessive voltage drop across resistor R1.
Surface-Mount Crystal
The EV kit comes with a 1.1mm cylindrical tuning fork crystal; however, the PC board layout accommodates an optional surface-mount crystal. Only one crystal may be used.
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MAX6902 Evaluation System/Evaluation Kit
Table 1. Jumper Functions
JUMPER JU1 POSITION *Closed Open VL = +5V User-supplied VL +5V Supply current-sensing resistor R1 is shorted, enabling communication with the real-time clock. Timekeeping supply current can be estimated by measuring voltage across R1. Communication is not possible in this state. FUNCTION
Evaluation of the MAX6902 at a Lower Voltage
To evaluate the MAX6902 at a lower voltage, remove the shunt from jumper JU1 and apply the desired voltage to the VL pad.
Evaluates: MAX6902
EV Kit Stand Alone
The MAX6902 EV kit can be connected to a different SPI interface with or without level translation. To connect with level translation, use the pads labeled X_DOUT, X_DIN, X_SCLK, and X_CS. Cut the trace shorting jumper JU7 and connect the SPI interface logic voltage to the VCC pad. Remove the shunt from jumper JU1 and apply the desired voltage for the MAX6902 to the VL pad. The voltage applied to VL must be less than or equal to VCC. Applying a higher voltage to VL damages the MAX3370 level translator. To connect without level translation, cut the traces shorting JU3, JU4, JU5, and JU6 and use the pads labeled DOUT, DIN, SCLK, and CS. Remove the shunt from jumper JU1 and connect the SPI interface logic voltage to the VL pad to power the MAX6902.
*Closed
JU2 Open
*Asterisk indicates default configuration.
MAXSMbus Connector
The MAXSMbus board connects to the MAX6902 EV kit in accordance with Table 2.
Table 2. MAXSMbus Connector Signals
PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 CONNECTOR P1 ON THE MAXSMbus BOARD +5V GND SDA GND GND GND SCL GND SMBSUS GND ALERT GND ALERT2 GND OUTA GND OUTB GND GND RAW PWR CONNECTOR J1 ON THE MAX6902 EV KIT No Connection Ground X_DOUT Ground Ground Ground X_SCLK Ground X_CS Ground No connection Ground No connection Ground X_DIN Ground No connection Ground Ground +9V
Troubleshooting
Problem: Unable to communicate while measuring supply current. Jumper JU2 must be closed to enable communication. Problem: Initial date POR value of RTC is 01-JAN-2070. RTC evaluation software was started. RTC time was set from computer clock. RTC was powered down. RTC evaluation software remained running and then RTC was powered back up. RTC evaluation software only reads the Century register when time is set from the computer clock or when the software is initially launched. Stop Cyclic Burst Read. Do a single read of the Century register. Continue by starting the Cyclic Burst Read.
Detailed Description of Software
The evaluation software provides access to all registers. The main timekeeping registers appear in the main screen, with other screens accessible from the View menu. To write to a single register, click on the appropriate register select button, set the desired value, and then click the Write button. To read a register, click on the appropriate register select button, and then click the Read button. Cyclic Burst Read should be disabled before a read or write to a single register.
Note: Odd-numbered pins are on the outer row. Even-numbered pins are on the inner row.
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MAX6902 Evaluation System/Evaluation Kit Evaluates: MAX6902
Figure 1. Main Screen
Main Screen
The Read button reads the most recently selected timekeeping register. The Write button writes the most recently selected timekeeping register. The Burst Read button performs a Burst Read from the timekeeping registers (except Century). The Burst Write button performs a Burst Write to the timekeeping registers (except Century). The Set from computer's clock button writes the PC's time into the MAX6902. The Cyclic Burst Read checkbox tells the software to perform a Burst Read from the timekeeping registers, at a rate of approximately 4 times per second. Updates are shown in the register display, along with the difference between MAX6902 time and the host PC's time. Note: Cyclic Burst Read should be disabled before a read or write to a single register. The Hour register setting can be switched from 12hr format to 24hr format by clicking the -->24 button.
most recently selected RAM location. The Burst Read button performs a Burst Read from the entire RAM. The Burst Write button performs a Burst Write to the RAM. Normally, all 31 locations are read; but the Burst Write length can be reduced. Burst Write always begins with RAM location 0. The Preset Data button performs a Burst Write to the RAM, setting all data to the same value. Note: Cyclic Burst Read should be disabled before reading or writing to RAM. Figure 2 is the RAM Screen.
Alarm Thresholds Screen
The Read button reads the most recently selected alarm threshold register. The Write button writes the most recently selected alarm threshold register. The Hour register setting can be switched from 12hr format to 24hr format by clicking the -->24 button. The time format should be the same in both the Alarm threshold and timekeeping registers. Note: Cyclic Burst Read should be disabled before a read or write to a single register. Figure 3 is the Alarm Thresholds screen.
RAM Screen
The Single Read button reads the most recently selected RAM location. The Single Write button writes the
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MAX6902 Evaluation System/Evaluation Kit Evaluates: MAX6902
Figure 2. RAM Screen
Figure 3. Alarm Thresholds Screen
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MAX6902 Evaluation System/Evaluation Kit
68HC11 SPI interface). The SPI interface sends and receives data simultaneously on separate pins. Parallel port pin 2 drives the SCLK, pin 1 drives DIN, pin 4 drives CS, and pin 11 senses DOUT. When the software is communicating through the MAXSMbus board, DOUT, CS, and SCLK are inverted. DIN is not inverted. The signals come out of the MAXSMbus at connector P1; DOUT is pin 3, CS is pin 9, SCLK is pin 7, and DIN is pin 15. The 3-wire interface uses a bidirectional data pin. The least-significant bit (LSB) is transmitted first, and (CPOL = 1, CPHA = 0) mode is used. Parallel port pin 2 drives SCLK, pin 11 drives I/O, and pin 4 drives CS. When the software is communicating through the MAXSMbus board, SCLK, I/O, and CS are inverted. The signals come out of the MAXSMbus at connector P1; SCLK is pin 7, CS is pin 9, and I/O is pin 3. When using this software, the data is relative to the parallel port. However, there are checkboxes that allow the signals to be inverted to accommodate the MAXSMbus board. Note: Disable Cyclic Burst Read when using the SPI/3Wire Diagnostic utility.
Figure 4. Setup Screen
Evaluates: MAX6902
Two-Wire Diagnostic Setup Screen
The transition from evaluation to custom software development requires access to the low-level interface. Access the 2-Wire Diagnostic from the main screen's View menu. The 2-Wire Diagnostic screen allows you to send general-purpose SMBus commands. The Hunt for active devices button scans the entire address space, reporting each address that is acknowledged. The two most-often-used protocols are SMBusReadByte and SMBusWriteByte. SMBusWriteByte transmits the device address, a command or register select byte, and 1 byte of data. SMBusReadByte transmits the device address, a command or register select byte, then retransmits the device address and reads 1 byte. Parallel port pin 2 drives the SMBCLK, pin 3 drives the SMBDATA, and pin 11 senses SMBDATA. The signals are inverted through the MAXSMbus board at connector P1. SMBCLK is pin 7, and SMBDATA is pin 3. The 2-Wire Interface Diagnostic software accounts for the logic inversion through the MAXSMbus board. Note: Disable Cyclic Burst Read when using the 2-Wire Diagnostic utility.
Each setup register is represented by a group of eight checkboxes, one for each bit. A checkmark indicates that the corresponding bit is a logic 1. The Read button updates the most recently selected setup register's checkboxes. The Write button writes the most recently selected setup register. Note: Cyclic Burst Read should be disabled before a read or write to a single register. Figure 4 is the Setup screen.
Auxiliary Functions
SPI/3-Wire Diagnostic
The transition from evaluation to custom software development requires access to the low-level interface. Access the SPI/3-Wire Diagnostic from the main screen's View menu. The SPI/3-wire Diagnostic screen allows you to send SPI or 3-Wire commands, or manipulate the parallel port pins directly. Each of the 25 parallel port pins is represented by a checkbox. A checkmark means that the corresponding pin is at a logichigh level. Pins that are inputs to the PC are grayed. The Bit-Banging SPI Diagnostic transmits data using synchronous serial format (similar to Motorola's
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MAX6902 Evaluation System/Evaluation Kit Evaluates: MAX6902
Figure 5. SPI/3-Wire Diagnostic
Figure 6. 2-Wire Interface Diagnostic _______________________________________________________________________________________ 7
MAX6902 Evaluation System/Evaluation Kit Evaluates: MAX6902
X_DOUT VCC 2 DVCC U2 VCC 9
1 DATA I/O
10 VL
SCLK JU4 CUT HERE JU3 2
1
SCLK
U1
X1
8
4
3 Y1 Y2
3 X_SCLK 4
MAX1840 LEVEL TRANSLATOR CLK CIN
8
MAX6902 DOUT RTC
X2
7
1
2 VL
CUT HERE DOUT 3 DIN VCC 6 C1 0.1F 5 R1 49.9k 1% JU2 JU5 CUT HERE CS
RIN X_CS VCC 5 SHDN
RST
7 4
GND
6
GND
CS
VCC TO MAXSMBUS BOARD J1-1 J1-3 J1-5 J1-7 J1-9 J1-11 J1-13 J1-15 J1-17 J1-19 NC NC NC NC NC X_SCLK X_CS NC J1-2 X_DOUT J1-4 J1-6 J1-8 J1-10 J1-12 J1-14 VCC X_DIN J1-16 J1-18 J1-20 +9V R2 470k JU7 CUT HERE 3 +9V C6 0.1F 1 IN SHDN 5 X_DIN 4 C3 0.1F 5 VCC U3 MAX3370 2 LEVEL GND TRANSLATOR I/O_VCC I/O_VL 3 SHDN 1
VL
C2 0.1F
JU6 DIN CUT HERE VCC VCC JU1 VL VL C5 10F 35V
U4
2
MAX1615 +5V GND LINEAR REGULATOR OUT 5/3 4 (FB)
1 2
C4 10F 35V
GND
Figure 7. MAX6902 EV Kit Schematic
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MAX6902 Evaluation System/Evaluation Kit Evaluates: MAX6902
1.0"
1.0"
Figure 8. MAX6902 EV Kit Component Placement Guide-- Component Side
Figure 9. MAX6902 EV Kit PC Board Layout--Component Side
1.0"
Figure 10. MAX6902 EV Kit PC Board Layout--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.
9 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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