EVALUATION FIXTURE PROVIDES FAST EASY PERFORMANCE TESTING ADS822/

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EVALUATION FIXTURE PROVIDES FAST EASY PERFORMANCE TESTING ADS822/

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DEM-ADS82xE
EVALUATION FIXTURE
PROVIDES FAST EASY PERFORMANCE TESTING ADS822/823/824 DC-COUPLED INPUTS SINGLE-ENDED DIFFERENTIAL INPUT CONFIGURATION EXTERNAL REFERENCE OPTION
DESCRIPTION
DEM-ADS82xE evaluation fixture designed ease when evaluating 10-bit high speed analog-to-digital converter ADS822, ADS823 ADS824. three converter feature different sampling rates, 40Msps, 60Msps 70Msps respectively, each model available individual demonstration board. Because flexible design user evaluate converter many different configurations: either with dc-coupled ac-coupled input, single-ended differential inputs. data output ADS82x converter decoupled from connector CMOS octal logic buffers.
International Airport Industrial Park Mailing Address: 11400, Tucson, 85734 Street Address: 6730 Tucson Blvd., Tucson, 85706 Tel: (520) 746-1111 Twx: 910-952-1111 Internet: http://www.burr-brown.com/ FAXLine: (800) 548-6133 (US/Canada Only) Cable: BBRCORP Telex: 066-6491 FAX: (520) 889-1510 Immediate Product Info: (800) 548-6132
1998 Burr-Brown Corporation
LI-509A
Printed U.S.A. December, 1999
INITIAL CONFIGURATION using solder switches resistor placements demonstration board, DEM-ADS82xE, variety configurations accommodate specific mode operation. Before starting evaluation, user should decide configuration make appropriate connections changes. demo board comes with following factory configuration: OPA681 non-inverting configuration with gain +2V/V 402). R12, R13, R15, assembled. With capacitor output driver OPA681 ac-coupled converter input. converter operate with internal reference-solder switch closed. full-scale input range 2Vp-p. solder switch open. required common-mode voltage bias input ADS82x derived from internal top- bottom references applied signal input ADS82x, (U1). bias complementary input ADS82x developed similar fashion using R23. POWER SUPPLY evaluation board typically operates with power supply. This supply, applied connector supply analog front separated from converter supply. ADS82x powered with supply through connector using negative supply driving applied input signal ground referenced signal with bipolar swing does need level shifted. However, input driver, OPA681, operate with single supply well. SIGNAL INPUT DC-Coupled standard configuration evaluation board uses high-speed OPA681, current-feedback type that features distortion. order implement level shifting dc-coupled circuit configuration needs re-configured inverting mode. this, remove install level shifting voltage derived from supply applied noninverting input. generate correct DC-voltage calculate appropriate values resistors close solder switch JP8. Note that this configuration input impedance board also determined input resistor, appropriate termination resistor (R7) value should selected. change input full-scale range from 2Vp-p 1Vp-p close solder switch JP4.
Transformer Coupled demonstration board provides option evaluate converter with differential signal inputs. Here, RFtransformer used convert single-ended input signal applied connector into differential signal. following steps have done prepare board: Remove resistors R19, R22, R23. Remove replace with 47pF capacitor. Remove R16, (C38). Install R21, typically Install RF-transformer (U5). model TT1-6, example, wideband RF-transformer manufactured `Mini-Circuits'. layout prepared `KK81' case style (surface mount). Note proper termination resistor depending selected transformer model. Install R17. Consider 0.1µF capacitor block path case input signal carries voltage. This differential input configuration operated with external references well. CLOCK evaluation board DEM-ADS82xE requires external clock applied connector This input represents input source. order preserve specified performance ADS82x converter clock source should feature very jitter. This particularly important converter evaluated undersampling condition. EXTERNAL REFERENCE ADS82x converter operated with external reference. this solder switch must opened disabling internal references. Close solder switches apply external reference voltage connector Refer converter data sheet recommended reference voltage ranges. selected reference voltage determines full-scale input signal range converter. DIGITAL OUTPUT DRIVER SUPPLY, VDRV ADS82x converter feature dedicated supply output logic drivers, VDRV, which internally connected other supply pins. This allows ADS82x interfaced either logic. evaluation board VDRV supply available connector shorted analog supply with resistor, R25. DATA OUTPUT data output provided CMOS logic levels. ADS82x converter straight offset binary coding. data output pins converter buffered from connector, CN1, CMOS octal buffer (FCT541).
DEM-ADS82xE
Clock Input
P3(1)
0.1µF 0.1µF 0.1µF
REFB REFT
0.1µF
49.9
100µF
100µF
100µF
VDRV ADS82xE
100µF
ADS82xE EVALUATION FIXTURE
IDT74FCT541T
2.2µF REFB
0.1µF
L2(1)
RSEL INT/EXT REFB 2.2µF 0.1µF
0.1µF
FIGURE Circuit Schematic DEM-ADS82xE.
R17(1) 1.1k R18(1) 1.1k
2.2µF 0.1µF REFT (LSB)
J3(1) DIFF. U5(1) TT1-6 R21(1)
1.1k
2.2µF 0.1µF 2.2µF 0.1µF REFT
(LSB)
1.1k
C36(1) 2.2µF 2.2µF
R24(1) 2.2µF
0.1µF
IDT74FCT541T 0.1µF (MSB)
0.1µF
C35(1) 0.1µF
49.9 R16(1)
C38(1) 2.2µF
47pF 2.2µF 0.1µF
(MSB)
OPA681U
R8(1)
0.1µF
0.1µF C32(1) 2.2µF 2.2µF
R15(1)
DEM-ADS82xE
0.1µF C31(1) 0.1µF
VDRV
49.9
R12(1)
2.2µF 0.1µF
VDRV
C37(1) 0.1µF
R13(1)
NOTE: Part assembled.
PC-BOARD LAYOUT DEM-ADS82xE demo board consists four layer board. achieve highest level performance surface mount components used wherever possible. This reduces trace length minimizes effects parasitic capacitance inductance. analog-to-digital converter
treated like analog component. Therefore demo board consistent ground plane. Keep mind that this approach necessarily yield optimum performance results when designing ADS82x into different individual applications. case, thoroughly bypassing power supply reference pins converter, demonstrated evaluation board, strongly recommended.
FIGURE Layer (Component Side) with Silk-Screen. ORDERING INFORMATION
PRODUCT DEM-ADS822E DEM-ADS823E DEM-ADS824E ANALOG-TO-DIGITAL CONVERTER ADS822E, 10-Bit 40Msps ADS823E, 10-Bit 60Msps ADS824E, 10-Bit 70Msps
DEM-ADS82xE
FIGURE Ground Plane.
FIGURE Power Plane.
DEM-ADS82xE
FIGURE Bottom Layer with Silk-Screen. COMPONENT LIST
REFERENCE COMPONENT ADS82xE 74FCT541 OPA681U DESCRIPTION High-Speed ADC, 28-Pin SSOP Octal Buffer, 20-Pin SOIC Wideband, Single Amp, SO-8 MANUFACTURER Burr-Brown Burr-Brown
R11, R19,
CRCW0805ZEROF CRCW080549R9F CRCW08054020F CRCW08051101F CRCW08051002F
0805 Chip Resistor, 49.9, 0805 Chip Resistor, 402, 0805 Chip Resistor, 1.1k, 0805 Chip Resistor, 10k, 0805 Chip Resistor, Open, Depends Configuration
Dale Dale Dale Dale Dale
C10, C31,
ECE-V1CV101SR TAJR225006
100µF/16V, Surface Mount Polar. Cap. 2.2µF/10V, 3216 Tantalum Capacitor
Panasonic (Digi-Key)
08055C104KAT 08055C470KAT
0.1µF/50V 0805 Ceramic Capacitor 47pF/50V 0805 Ceramic Capacitor Open, Depends Configuration
ED555/3DS IDH-40LP-S3-TG
3-Pin Term Block Dual-Row Shrouded Header
On-Shore Technology Robinson-Nugent
142-0701-201 1-SJ5003-0-N A2403
Straight Connector Rubber Feet, Black, 0.44 Board A2403, Rev.
Johnson Digi-Key Burr-Brown
DEM-ADS82xE

EVALUATION FIXTURE PROVIDES FAST EASY PERFORMANCE TESTING ADS822/

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