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CMOS 8-Bit High Speed Analog-to-Digital Converter
April 2002-4
XRD8775
FEATURES
· 8-Bit Resolution · Up to 20MHz Sampling Rate · Internal S/H Function · Single Supply: 5V · VIN DC Range: 0V to VDD · VREF DC Range: 1V to VDD · Low Power: 75mW typ. (excluding reference) · Latch-Up Free · ESD Protection: 2000V Minimum
· 3V Version: XRD87L75 · Small 20-Pin SOIC/SSOP Packages
APPLICATIONS · Digital Color Copiers
· Cellular Telephones · CCD-Based Systems · Hardware Scanners · Video Capture Boards
GENERAL DESCRIPTION The XRD8775 is an 8-bit Analog-to-Digital Converter in a small 20-pin SOIC/SSOP package. Designed using an advanced 5V CMOS process, this part offers excellent performance, low power consumption and latch-up free operation. This device uses a two-step flash architecture to maintain low power consumption at high conversion rates. The input circuitry of the XRD8775 includes an on-chip S/H function and allows the user to digitize analog input signals between AGND and AVDD. Careful design and chip layout have achieved a low analog input capacitance. This reduces “kickback” and eases the requirements of the buffer/amplifier used to drive the XRD8775.
The designer can choose the internally generated reference voltages by connecting VRB to VRBS and VRT to VRTS , or provide external reference voltages to the VRB and VRT pins. The internal reference generates 0.6V at VRB and 2.6V at VRT. Providing external reference voltages allows easy interface to any input signal range between GND and VDD. This also allows the system to adjust these voltages to cancel zero scale and full scale errors, or to change the input range as needed. The device operates from a single +5V supply. Power consumption is 75mW at FS = 15MHz. Specified for operation over the commercial / industrial (-40 to +85°C) temperature range, the XRD8775 is available in Surface Mount (SOIC), Shrink Small Outline (SSOP) and Plastic Dual-In-line (PDIP) Packages.
SIMPLIFIED BLOCK AND TIMING DIAGRAM
Rev. 4.00 EXAR Corporation, 48720 Kato Road, Fremont, CA 94538 • (510) 668-7000 • FAX (510) 668-7017
XRD8775
ORDERING INFORMATION
Package Type SOIC PDIP SSOP Temperature Range -40 to +85°C -40 to +85°C -40 to +85°C DNL (LSB) +/-0.75 +/-0.75 +/-0.75 INL (LSB) +/-1.5 +/-1.5 +/-1.5
Part No. XRD8775AID XRD8775AIP XRD8775AIU
PIN CONFIGURATIONS
See Packaging Section for Package Dimensions
20-Pin PDIP (300 MIL) - P20
20-Pin SOIC (Jedec, 300 MIL) - D20 20-Pin SSOP (5.3mm) - U20
PIN OUT DEFINITIONS
PIN NO. 1 2 3 4 5 6 7 8 9 10 NAME DGND DB0 DB1 DB2 DB3 DB4 DB5 DB6 DB7 DVDD DESCRIPTION Digital Ground Data Output Bit 0 (LSB) Data Output Bit 1 Data Output Bit 2 Data Output Bit 3 Data Output Bit 4 Data Output Bit 5 Data Output Bit 6 Data Output Bit 7 (MSB) Digital Power Supply PIN NO. 11 12 13 14 15 16 17 18 19 20 NAME CLK DVDD VRTS VRT AVDD VIN AGND VRBS VRB DGND DESCRIPTION Sample Clock Digital Power Supply Generates 2.6V if tied to VRT Top Reference Analog Power Supply Analog Input Analog Ground Generates 0.6V if tied to VRB Bottom Reference Digital Ground
Rev. 4.00
2
XRD8775
ELECTRICAL CHARACTERISTICS TABLE UNLESS OTHERWISE SPECIFIED: AVDD = DVDD = 5V, FS = 15MHZ (50% DUTY CYCLE), VRT = 2.6V, VRB = 0.6V, TA = 25°C
25°C Parameter KEY FEATURES Resolution Sampling Rate ACCURACY Differential Non-Linearity Differential Non-Linearity Integral Non-Linearity Zero Scale Error Full Scale Error REFERENCE VOLTAGES Positive Ref. Voltage Negative Ref. Voltage Differential Ref. Voltage3 Ladder Resistance Ladder Temp. Coefficient Self Bias 1 Short VRB and VRBS Short VRT and VRTS Self Bias 2 VRB = AGND, Short VRT and VRTS ANALOG INPUT Input Bandwidth (–1 dB)2, 4 Input Voltage Range Input Capacitance Aperture Delay2 DIGITAL INPUTS Logical “1” Voltage Logical “0” Voltage DC Leakage Current 6 CLK Input Capacitance Clock Timing ( See Figure 1.)7 Clock Period High Pulse Width Low Pulse Width DIGITAL OUTPUTS Logical “1” Voltage Logical “0” Voltage Data Valid Delay 8 VOH VOL t DL 10 4.5 0.4 V V ns 1/FS tPWH tPWL 50 25 25 66.7 33.3 33.3 ns ns ns C OUT =15 pF I LOAD = 4 mA I LOAD = 4 mA VIH VIL IIN 5 5 4.0 1.0 V V VIN =DGND to DVDD
5
Symbol
Min 8
Typ
Max
Units Bits
Test Conditions/Comments
FS DNL DNL INL EZS EFS VRT VRB V REF RL RTCO VRB VRT-VRB VRT
0.1
15
20 +/-0.75
MHz LSB LSB LSB LSB LSB @ 15MHz @ 10MHz Best Fit Line (Max INL – Min INL)/2
+/-0.5 +/-1.5 +3 -2 2.6 AGND 1.0 245 350 2000 0.6 2 2.3 0.6 AVDD 550 AVDD
V V V VREF = VRT – VRB
Ω
ppm/°C V V V
BW VIN CIN tAP VRB
50 VRT 16 3
MHz V pF ns
µA
pF
Rev. 4.00
3
XRD8775
ELECTRICAL CHARACTERISTICS TABLE (CONT'D) UNLESS OTHERWISE SPECIFIED: AVDD = DVDD = 5V, FS = 15MHZ (50% DUTY CYCLE), VRT = 2.6V, VRB = 0.6V, TA = 25°C
25°C Parameter AC PARAMETERS Differential Gain Error Differential Phase Error POWER SUPPLIES Operating Voltage (AVDD, DVDD)9 Current (AGND + DGND) VDD I DD 4.5 5 15 5.5 25 V mA Does not include ref. current dG dPH 2 1 % Degree FS = 4 x NTSC FS = 4 x NTSC Symbol Min Typ Max Un.