LTC2421/LTC2422 1-/2-Channel 20-Bit m Power TM No Latency DS ADCs in MSOP-10 FEATURES DESCRIPTIO n 20-Bit ADCs in Tiny MSOP-10 Packages The LTC 2421/LTC2422 are 1- and 2-channel 2.7V to 5.5V n 1- or 2-Channel Inputs micropower 20-bit analog-to-digital converters with an n Single Supply 2.7V to 5.5V Operation integrated oscillator, 8ppm INL and 1.2ppm RMS noise. n Low Supply Current (200m A) and Auto Shutdown These ultrasmall devices use delta-sigma technology and n Automatic Channel Selection (Ping-Pong) (LTC2422) a new digital filter architecture that settles in a single cycle. n No Latency: Digital Filter Settles in a This eliminates the latency found in conventional Single Conversion Cycle converters and simplifies multiplexed applications. n 8ppm INL, No Missing Codes Through a single pin, the LTC2421/LTC2422 can be n 4ppm Full-Scale Error configured for better than 110dB rejection at 50Hz or n 0.5ppm Offset 60Hz 2%, or can be driven by an external oscillator for n 1.2ppm Noise a user defined rejection frequency in the range 1Hz to n Zero Scale and Full Scale Set for Reference 120Hz. The internal oscillator requires no external fre- and Ground Sensing quency setting components. n Internal OscillatorNo External Components Required n These converters accept an external reference voltage 110dB Min, 50Hz/60Hz Notch Filter n from 0.1V to V . With an extended input conversion Reference Input Voltage: 0.1V to V CC CC n range of 12.5% V to 112.5% V (V = FS Live ZeroExtended Input Range Accommodates REF REF REF SET ZS ), the LTC2421/LTC2422 smoothly resolve the off- 12.5% Overrange and Underrange SET n set and overrange problems of preceding sensors or Pin Compatible with LTC2401/LTC2402 signal conditioning circuits. U APPLICATIO S The LTC2421/LTC2422 communicate through a 2- or 3-wire digital interface that is compatible with SPI and n Weight Scales TM MICROWIRE protocols. n Direct Temperature Measurement , LTC and LT are registered trademarks of Linear Technology Corporation. n Gas Analyzers No Latency is a trademark of Linear Technology Corporation. n MICROWIRE is a trademark of National Semiconductor Corporation. Strain Gauge Transducers n Instrumentation n Data Acquisition n Industrial Process Control Pseudo Differential Bridge Digitizer TYPICAL APPLICATIO 2.7V TO 5.5V 2.7V TO 5.5V 1 V CC 1F V CC = INTERNAL OSC/50Hz REJECTION 110 = EXTERNAL CLOCK SOURCE LTC2422 V F CC O 2 = INTERNAL OSC/60Hz REJECTION FS 9 SET LTC2422 SCK 2 9 REFERENCE VOLTAGE 4 FS SCK SET 8 3-WIRE ZS + 0.1V TO V CH0 SET CC SDO SPI INTERFACE 3 8 3-WIRE ANALOG INPUT RANGE CH1 SDO 3 7 SPI INTERFACE ZS 0.12V TO CH1 CS SET REF FS + 0.12V 4 7 SET REF CH0 CS 10 5 (V = FS ZS ) REF SET SET ZS F SET O INTERNAL OSCILLATOR 5 6 GND 60Hz REJECTION 0V TO FS 100mV ZS GND SET SET 6 24212 TA01 24012TA02 24212f 1 U DS DS ULTC2421/LTC2422 ABSOLUTE MAXIMUM RATINGS (Notes 1, 2) Supply Voltage (V ) to GND.......................0.3V to 7V Operating Temperature Range CC Analog Input Voltage to GND ....... 0.3V to (V + 0.3V) LTC2421/LTC2422C ................................ 0 C to 70 C CC Reference Input Voltage to GND .. 0.3V to (V + 0.3V) LTC2421/LTC2422I ............................ 40 C to 85 C CC Digital Input Voltage to GND ........ 0.3V to (V + 0.3V) Storage Temperature Range ................. 65 C to 150 C CC Digital Output Voltage to GND ..... 0.3V to (V + 0.3V) Lead Temperature (Soldering, 10 sec).................. 300 C CC UUW PACKAGE/ORDER INFORMATION ORDER PART NUMBER ORDER PART NUMBER TOP VIEW TOP VIEW LTC2421CMS V V 1 10 F 1 10 F LTC2422CMS CC O CC O FS FS 2 9 SCK 2 9 SCK SET SET LTC2421IMS LTC2422IMS CH1 V 3 8 SDO 3 8 SDO IN CH0 NC 4 7 CS 4 7 CS ZS ZS 5 6 GND 5 6 GND SET SET MS10 PART MARKING MS10 PART MARKING MS10 PACKAGE MS10 PACKAGE 10-LEAD PLASTIC MSOP 10-LEAD PLASTIC MSOP LTUX LTUZ T = 125 C, q = 130 C/W T = 125 C, q = 130 C/W JMAX JA JMAX JA LTUY LTVA Consult factory for parts specified with wider operating temperature ranges. CONVERTER CHARACTERISTICS The l denotes specifications which apply over the full operating temperature range, otherwise specifications are at T = 25 C. V = FS ZS . (Notes 3, 4) A REF SET SET PARAMETER CONDITIONS MIN TYP MAX UNITS Resolution l 20 Bits No Missing Codes Resolution 0.1V FS V , ZS = 0V (Note 5) l 20 Bits SET CC SET Integral Nonlinearity FS = 2.5V, ZS = 0V (Note 6) l 4 10 ppm of V SET SET REF FS = 5V, ZS = 0V (Note 6) l 8 20 ppm of V SET SET REF Offset Error 2.5V FS V , ZS = 0V l 0.5 10 ppm of V SET CC SET REF Offset Error Drift 2.5V FS V , ZS = 0V 0.04 ppm of V / C SET CC SET REF Full-Scale Error 2.5V FS V , ZS = 0V l 4 10 ppm of V SET CC SET REF Full-Scale Error Drift 2.5V FS V , ZS = 0V 0.04 ppm of V / C SET CC SET REF Total Unadjusted Error FS = 2.5V, ZS = 0V 8 ppm of V SET SET REF FS = 5V, ZS = 0V 16 ppm of V SET SET REF Output Noise V = 0V (Note 13) 6 m V IN RMS Normal Mode Rejection 60Hz 2% (Note 7) l 110 130 dB Normal Mode Rejection 50Hz 2% (Note 8) l 110 130 dB Power Supply Rejection, DC FS = 2.5V, ZS = 0V, V = 0V 100 dB SET SET IN Power Supply Rejection, 60Hz 2% FS = 2.5V, ZS = 0V, V = 0V, (Notes 7, 15) 110 dB SET SET IN Power Supply Rejection, 50Hz 2% FS = 2.5V, ZS = 0V, V = 0V, (Notes 8, 15) 110 dB SET SET IN 24212f 2 U U WWW