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19-1911; Rev 0; 9/00
MAX1425 Evaluation Kit
General Description
The MAX1425 evaluation kit (EV kit) is an assembled and tested board for prototyping designs using the MAX1425 or MAX1426 analog-to-digital converters (ADCs). The board interfaces to a user-provided logic analyzer or data-acquisition system. An external clock generator and +5V power supply are required. o 20Msps Conversion Rate o Clock Shaping Circuit o On-Board TTL Buffers o Wideband Transformer Accepts Single-Ended Input o Fully Assembled and Tested
Features
Evaluates: MAX1425/MAX1426
Ordering Information
PART MAX1425EVKIT TEMP. RANGE -40C to +85C IC PACKAGE 28 SSOP
Component List
DESIGNATION QTY C1, C4-C8, C15, C16, C20, C22, C25, C27, C30, C34, C35, C37 C2, C10 C3, C9 C11, C17, C18, C21, C26, C28, C29, C31, C32, C33 C12, C13, C14, C23 J1 REF IN, IN1, CLK IN JU1 JU2 R1 R2, R3, R35, R38 DESCRIPTION DESIGNATION QTY R4, R5 R6, R7, R8 16 0.1F ceramic capacitors (0805) R9 R10 2 2 100pF ceramic capacitors (0805) 22pF ceramic capacitors (0805) 2.2F, 10V capacitors Sprague 595D "A" case size 100F, 25V capacitors Sprague 595D "R" case size 2x10-pin header T1 3 1 1 1 4 SMA connectors 2-pin header 3-pin header 2k 5% resistor (0805) 100 5% resistors (0805) U1 U2, U3 U4 U5 1 2 1 1 1 R11 R12 R13-R33 R34 R36 R37 1 1 1 1 21 1 1 1 2.5k 5% resistor (1206) 2.5k 5% resistor (0805) 1k 5% resistor (0805) 4k 5% resistor (0805) 200 5% resistors (0805) 2k potentiometer 3k 5% resistor (0805) 100 5% resistor (1206) Transformer Minicircuits T1-1T-KK81 Maxim MAX1425EAI 74ALS541A Maxim MAX473ACSA Maxim MAX961CSA 2 3 DESCRIPTION 25 5% resistors (1206) 51 5% resistors (1206)
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________________________________________________________________ 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.
MAX1425 Evaluation Kit Evaluates: MAX1425/MAX1426
_________________________Quick Start
You'll need the following required equipment: * DC power supplies: 2 each (use for digital +5V and analog +5V) * Function generator for clock input, 2Vp-p * Function generator for signal input, 2Vp-p * Logic analyzer or data-acquisition system * Voltage reference (optional) Note: To ensure maximum performance, use a clock generator with low phase noise, such as the HP 8662A filtered with an appropriate bandpass filter. The MAX1425 EV kit is fully assembled and tested. Follow these steps to verify board operation. Do not turn on the power supply until all connections are complete. 1) Connect one +5V DC power supply to +5VA and +5VADUT. Connect the negative terminal of this supply to AGND. Connect the second +5V supply to +5VDDUT and +5VD. Connect the negative terminal of the second supply to DGND. See Table 1. 2) If using an external reference, connect a 2.500V 1mV voltage reference to the REF IN connector. If using the internal reference, do not connect anything to the REF IN connector. 3) Connect a 20MHz, 1Vp-p clock function generator to the CLK IN connector. 4) Connect the signal function generator to the IN1 connector. 5) Connect a logic analyzer (e.g. HP16500C) or dataacquisition system to header J1. Configure jumpers JU1 and JU2 as shown in Table 2. 6) Turn on the power supplies and reference supply (if used). 7) Enable the function generators. Adjust potentiometer R34 so that the strobe signal has 50% duty cycle. 8) Begin acquiring digital data. used with a user-supplied data-acquisition system. Jumper JU2 selects the polarity of the J1 strobe signal. The analog input signal from the IN1 connector is terminated by R2/R3 and coupled through transformer T1. The transformer converts the single-ended input into a differential signal between VINP and VINN, with commonmode voltage set by the CML pin and buffered by U4. The device under test, U1, samples analog input VINPVINN. Its digital outputs are buffered by U2 and U3 (74ALS541). The twenty 200 series resistors help isolate the A/D converter from switching transients. The buffered digital outputs appear on connector J1.
Performance Considerations
Careful attention to setup and testing is necessary to achieve optimum results with this high-performance converter. Precise and accurate phase-locked signal sources should be employed in all cases. Low jitter sources, such as the HP 8664B for the input phaselocked with a second low-jitter clock generator, will give the best results. In addition, lowpass or bandpass filters should be used on the input signal to ensure that the MAX1425's low-distortion characteristics are maintained.
Table 1. Power Connections
TERMINAL +5VA +5VADUT AGND DGND +5VDDUT +5VD FUNCTION Analog Supply to the Signal Conditioning Op Amps Analog Supply to the Device Under Test Analog Ground Return Digital Ground Return Digital Supply to the Device Under Test Digital Supply to the Digital Buffers
Detailed Description of the Hardware
The MAX1425 EV kit is a proven PC board layout pattern that gives good analog performance. Refer to the MAX1425 data sheet for more information. The clock signal from the CLK IN connector is terminated by R35/R38 and AC-coupled by C16 into U5, the MAX961 comparator. Potentiometer R34 sets the clock threshold. Comparator U5 produces a square-wave output, driving the MAX1425 and providing a clock output (J1-20) to be
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Table 2. Jumper Settings
JUMPER JU1 SETTING Open Closed 1-2 (bottom position) JU2 2-3 (top position) STROBEIN polarity is the opposite of CLK FUNCTION Output Enable = low (enabled) Output Enable = high (disabled) STROBEIN polarity is the same as CLK
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J11 +5VA C23 100F 25V +5VA +5VD R23 200 J1-1 C34 1 19 DGND U3 R21 200 J1-5 R20 200 J1-7 R19 200 J1-9 R18 200 J1-11 C35 R28 200 R27 200 R26 200 R25 200 R24 200 1 19 OE1 OE2 U2 0.1F 20 VCC 10 GND R17 200 J1-13 R16 200 J1-15 R15 200 J1-17 R14 200 74ALS541A JU1 +5VDDUT R1 2k R7 51 R13 200 J1-20 J1-19 J1-18 J1-16 J1-14 J1-12 J1-10 J1-8 J1-6 OE1 OE2 20 VCC 10 GND J1-3 0.1F R22 200 J1-4 J1-2 C31 2.2F 10V J9 J7 AGND DGND J10 +5VD C18 2.2F 10V 4 REFIN D0 U1 D1 D2 D3 D4 DVDD DVDD DGND DGND D5 D6 D7 D8 D9 15 16 17 18 19 23 21 22 C20 0.1F C21 2.2F 10V C1 0.1F 20 200 +5VDDUT C29 2.2F 10V 24 R29 200 25 R30 26 200 R31 200 27 R32 3 REFP 6 CML 28 R33 200 C14 100F 25V +5VD
J6
+5VADUT
C12 +5VADUT 100F 25V J12
Figure 1. MAX1425 EV Kit Schematic
MAX1425
5 REFN 8 AV DD 2 AV DD 1 AGND C10 100pF C37 0.1F 9 VINP 10 VINN 11 CMLP INP 12 CMLN 13 CLK 14 OE/PD C4 0.1F +5VADUT C17 2.2F 10V INN C11 2.2F 10V 7 AGND 2 3 4 5 6 7 8 9 A0 A1 A2 A3 A4 A5 A6 A7 +5VD 74ALS541A C26 2.2F 10V Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 18 17 16 15 14 13 12 11 C2 100pF C27 0.1F C28 2.2F 10V CML 2 3 4 5 6 7 8 9 A0 A1 A2 A3 A4 A5 A6 A7 Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 18 17 16 15 14 13 12 11 CLK CLK IN R8 51 C24 50pF STROBE IN C19 50pF
+5VDDUT
REF IN C13 100F +5VDDUT J5 25V
C8 0.1F
C7 0.1F
C6 0.1F
AGND
C5 0.1F
+5VADUT
IN1 J2
SEE ANALOG INTERFACE PAGE
IN1
SEE CLOCK INTERFACE PAGE
Evaluates: MAX1425/MAX1426
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CLK J4
MAX1425 Evaluation Kit
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MAX1425 Evaluation Kit Evaluates: MAX1425/MAX1426
+5VA
C30 0.1F U4 7 MAX473A 6 4 2 AGND 3 R10 2.5k
R6 51 R4 25 C3 22pF IN1 R2 100 R3 100 N.C. 1 2 3 6 5 4 R5 25 C9 22pF INP INN
C15 0.1F
R9 2.5k
MINICIRCUITS T1-1T-KK81
+5VA
+5VA
R37 100 R34 2k R36 3k +5VA
C32 2.2F 10V
C25 0.1F
C33 2.2F 10V
C22 0.1F 1 4 LE U5 R11 1k MAX961 SHDN 2 C16 0.1F R12 4k GND 5 3 8 VCC Q Q 6 7 JU2
3 2 1
STROBEIN
CLK IN R35 100 R38 100
CLK
AGND
Figure 1. MAX1425 EV Kit Schematic (continued) 4 _______________________________________________________________________________________
MAX1425 Evaluation Kit Evaluates: MAX1425/MAX1426
Figure 2. MAX1425 EV Kit Component Placement Guide--Component Side
Figure 3. MAX1425 EV Kit Component Placement Guide--Reverse Side
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MAX1425 Evaluation Kit Evaluates: MAX1425/MAX1426
Figure 4. MAX1425 EV Kit PC Board Layout--Layer 1
Figure 5. MAX1425 EV Kit PC Board Layout--Layer 2
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MAX1425 Evaluation Kit Evaluates: MAX1425/MAX1426
Figure 6. MAX1425 EV Kit PC Board Layout--Layer 3
Figure 7. MAX1425 EV Kit PC Board Layout--Layer 4
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.
7 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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