Owner manual

ManualsBrandsRainbow Electronics ManualsSensorsADC1175

Table Of Contents

ADC1175

ADC1175

8-Bit, 20MHz, 60mW A/D Converter

General Description

The ADC1175 is a low power, 20 Msps analog-to-digital

converter that digitizes signals to 8 bits while consuming just

60 mW of power (typ). The ADC1175 uses a unique archi-

tecture that achieves 7.5 Effective Bits. Output formatting is

straight binary coding.

The excellent DC and AC characteristics of this device,

together with its low power consumption and +5V single

supply operation, make it ideally suited for many video,

imaging and communications applications, including use in

portable equipment. Furthermore, the ADC1175 is resistant

to latch-up and the outputs are short-circuit proof. The top

and bottom of the ADC1175’s reference ladder is available

for connections, enabling a wide range of input possibilities.

The ADC1175 is offered in SOIC (EIAJ) and TSSOP. It is

designed to operate over the commercial temperature range

of -20˚C to +75˚C.

Features

n Internal Sample-and-Hold Function

n Single +5V Operation

n Internal Reference Bias Resistors

n Industry Standard Pinout

n TRI-STATE Outputs

Key Specifications

Resolution 8 Bits

Maximum Sampling Frequency 20 Msps (min)

THD −55 dB (typ)

DNL 0.75 LSB (max)

ENOB 7.5 Bits (typ)

Guaranteed No Missing Codes

Differential Phase 0.5 Degree (typ)

Differential Gain 0.4% (typ)

Power Consumption

(excluding reference current)

60mW (typ)

Applications

n Video Digitization

n Digital Still Cameras

n Set Top Boxes

n Communications

n Medical Imaging

n Personal Computer Video Cameras

n Digital Television

n CCD Imaging

n Electro-Optics

Pin Configuration

ADC1175 Pin Configuration

10009201

March 2003

ADC1175 8-Bit, 20MHz, 60mW A/D Converter

Summary of content (19 pages)

PAGE 1
ADC1175 8-Bit, 20MHz, 60mW A/D Converter General Description Features The ADC1175 is a low power, 20 Msps analog-to-digital converter that digitizes signals to 8 bits while consuming just 60 mW of power (typ). The ADC1175 uses a unique architecture that achieves 7.5 Effective Bits. Output formatting is straight binary coding.
PAGE 2
ADC1175 Ordering Information ADC1175CIJM SOIC (EIAJ) ADC1175CIJMX SOIC (EIAJ) (tape & reel) ADC1175CIMTC TSSOP ADC1175CIMTCX TSSOP (tape & reel) Block Diagram 10009202 Pin Descriptions and Equivalent Circuits Pin No. Symbol Description Equivalent Circuit 19 VIN Analog signal input. Conversion range is VRB to VRT. 16 VRTS Reference Top Bias with internal pull-up resistor. Short this pin to VRT to self bias the reference ladder. www.national.
PAGE 3
Pin No. Symbol ADC1175 Pin Descriptions and Equivalent Circuits (Continued) Description Equivalent Circuit VRT Analog Input that is the high (top) side of the reference ladder of the ADC. Nominal range is 1.0V to AVDD. Voltage on VRT and VRB inputs define the VIN conversion range. Bypass well. See Section 2.0 for more information. 23 VRB Analog Input that is the low (bottom) side of the reference ladder of the ADC. Nominal range is 0V to 4.0V.
PAGE 4
ADC1175 Pin Descriptions and Equivalent Circuits Pin No. Symbol (Continued) Description Equivalent Circuit DVSS The ground return for the digital supply. AVSS and DVSS should be connected together close to the ADC1175. 14, 15, 18 AVDD Positive analog supply pin. Connected to a clean, quiet voltage source of +5V. AVDD and DVDD should have a common source and be separately bypassed with a 10 µF capacitor and a 0.1 µF ceramic chip capacitor. See Section 3.0 for more information.
PAGE 5
Operating Ratings(Notes 1, 2) (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. AVDD, DVDD 6.5V Voltage on Any Pin −0.3V to 6.5V VRT, VRB AVSS to AVDD CLK, OE Voltage −0.5 to (AVDD + 0.5V) Digital Output Voltage DVSS to DVDD Input Current (Note 3) ± 25mA Package Input Current (Note 3) −20˚C ≤ TA ≤ +75˚C Temperature Range AVDD, DVDD +4.75V to +5.25V AVDD − DVDD < 0.
PAGE 6
ADC1175 Converter Electrical Characteristics (Continued) The following specifications apply for AVDD = DVDD = +5.0VDC, OE = 0V, VRT = +2.6V, VRB = 0.6V, CL = 20 pF, fCLK = 20MHz at 50% duty cycle.
PAGE 7
ADC1175 Converter Electrical Characteristics (Continued) The following specifications apply for AVDD = DVDD = +5.0VDC, OE = 0V, VRT = +2.6V, VRB = 0.6V, CL = 20 pF, fCLK = 20MHz at 50% duty cycle. Boldface limits apply for TA = TMIN to TMAX; all other limits TA = 25˚C (Notes 7, 8) Symbol Parameter Typical (Note 9) Conditions Limits (Note 9) Units Signal-to- Noise & Distortion fIN fIN fIN fIN = = = = 1.31 MHz, VIN = FS - 2 LSB 4.43 MHz, VIN = FS - 2 LSB 9.9 MHz, VIN = FS - 2 LSB 4.
PAGE 8
ADC1175 Typical Performance Characteristics INL vs Temp at fCLK DNL vs Temp at fCLK 10009221 10009220 SNR vs Temp at fCLK SNR vs Temp at fCLK 10009222 10009233 THD vs Temp THD vs Temp 10009223 www.national.
PAGE 9
ADC1175 Typical Performance Characteristics (Continued) SINAD/ENOB vs Temp SINAD/ENOB vs Temp 10009224 10009231 SINAD and ENOB vs Clock Duty Cycle SFDR vs Temp and fIN 10009225 10009229 SFDR vs Temp and fIN Differential Gain vs Temperature 10009226 10009230 9 www.national.
PAGE 10
ADC1175 Typical Performance Characteristics (Continued) Differential Phase vs Temperature Spectral Response at fCLK = 20 MSPS 10009227 10009228 OUTPUT HOLD TIME is the length of time that the output data is valid after the rise of the input clock. Specification Definitions ANALOG INPUT BANDWIDTH is a measure of the frequency at which the reconstructed output fundamental drops 3 dB below its low frequency value for a full scale input.
PAGE 11
ADC1175 Timing Diagram 10009211 FIGURE 1. ADC1175 Timing Diagram 10009212 FIGURE 2. tEN, tDISTest Circuit 11 www.national.
PAGE 12
ADC1175 components. With no adjustments, the nominal value for the amplifier feedback resistor is 560Ω and the 5.1k resistor at the inverting input should be changed to 1.5k and returned to +5V rather than to the Offset Adjust potentiometer. Driving the analog input with input signals up to 2.8 VP-P will result in normal behavior where signals above VRT will result in a code of FFh and input voltages below VRB will result in an output code of zero. Input signals above 2.
PAGE 13
ADC1175 Applications Information (Continued) 10009213 FIGURE 3. Simple, Low Component Count, Self -Bias Reference application. Because of resistor tolerances, the reference voltages can vary by as much as 6%. Choose an amplifier that can drive a dynamic capacitance (see text). 13 www.national.
PAGE 14
ADC1175 Applications Information (Continued) 10009214 FIGURE 4. Better defining the ADC Reference Voltage. Self-bias is still used, but the reference voltages are trimmed by providing a small trim current with the operational amplifiers. www.national.
PAGE 15
ADC1175 Applications Information (Continued) 10009215 FIGURE 5. Driving the reference to force desired values requires driving with a low impedance source, provided by the transistors. Note that pins 16 and 22 are not connected. power pins, with a 0.1 µF ceramic chip capacitor placed as close as possible to the converter’s power supply pins. Leadless chip capacitors are preferred because they have low lead inductance.
PAGE 16
ADC1175 Applications Information An effective way to control ground noise is by connecting the analog and digital ground planes together beneath the ADC with a copper trace that is very narrow (about 3/16 inch) compared with the rest of the ground plane. This narrowing beneath the converter provides a fairly high impedance to the high frequency components of the digital switching currents, directing them away from the analog pins.
PAGE 17
dynamic capacitance is more difficult to drive than is a fixed capacitance, and should be considered when choosing a driving device. The CLC409, CLC440, LM6152, LM6154, LM6181 and LM6182 have been found to be excellent devices for driving the ADC1175 analog input. Driving the VRT pin or the VRB pin with devices that can not source or sink the current required by the ladder. As mentioned in section 2.
PAGE 18
ADC1175 Physical Dimensions inches (millimeters) unless otherwise noted 24-Lead Package JM Ordering Number ADC1175CIJM NS Package Number M24D www.national.
PAGE 19
ADC1175 8-Bit, 20MHz, 60mW A/D Converter Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 24-Lead Package TC Ordering Number ADC1175CIMTC NS Package Number MTC24 LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1.