LTC2424/LTC2428 4-/8-Channel 20-Bit m Power TM No Latency DS ADCs FEATURES DESCRIPTIO n Pin Compatible 4-/8-Channel 20-Bit ADCs The LTC 2424/LTC2428 are 4-/8-channel 2.7V to 5.5V n 8ppm INL, No Missing Codes at 20 Bits micropower 20-bit A/D converters with an integrated n 4ppm Full-Scale Error and 0.5ppm Offset oscillator, 8ppm INL and 1.2ppm RMS noise. They use n 1.2ppm Noise delta-sigma technology and provide single cycle digital n Digital Filter Settles in a Single Cycle. Each filter settling time (no latency delay) for multiplexed Conversion is Accurate, Even After Changing applications. The first conversion after the channel is Channels changed is always valid. Through a single pin the LTC2424/ n Fast Mode: 16-Bit Noise, 12-Bit TUE at 100sps LTC2428 can be configured for better than 110dB rejec- n Internal OscillatorNo External Components tion at 50Hz or 60Hz 2%, or can be driven by an external Required oscillator for a user defined rejection frequency in the n 110dB Min, 50Hz/60Hz Notch Filter range 1Hz to 800Hz. The internal oscillator requires no n Reference Input Voltage: 0.1V to V external frequency setting components. CC n Live ZeroExtended Input Range Accommodates The converters accept any external reference voltage from 12.5% Overrange and Underrange 0.1V to V . With their extended input conversion range of CC n Single Supply 2.7V to 5.5V Operation 12.5% V to 112.5% V (V = FS ZS ) the REF REF REF SET SET n Low Supply Current (200m A) and Auto Shutdown LTC2424/LTC2428 smoothly resolve the offset and n Can Be Interchanged with 24-Bit LTC2404/LTC2408 overrange problems of preceding sensors or signal con- if ZS Pin is Grounded SET ditioning circuits. U APPLICATIO S The LTC2424/LTC2428 communicate through a flexible 4-wire digital interface which 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. MICROWIRE is a trademark of National Semiconductor Corporation. n Strain-Gage Transducers n Instrumentation n Data Acquisition n Industrial Process Control n 4-Digit DVMs TYPICAL APPLICATIO Total Unadjusted Error (3V Supply) 10 0.1V TO V V = 3V CC 2.7V TO 5.5V CC 8 V = 2.5V REF 7 4 3 2, 8 1F 6 MUXOUT ADCIN FS V SET CC SERIAL DATA LINK 9 CH0 4 MICROWIRE AND 23 10 CH1 CSADC SPI COMPATABLE 2 20 11 CH2 CSMUX 0 25 ANALOG 12 CH3 20-BIT SCK INPUTS 4-/8-CHANNEL + 19 2 S ADC 13 CH4* CLK MPU MUX 0.12V TO REF 21 1.12V 14 CH5* 4 REF D IN T = 55C, 45C, 25C, 90C 24 A 15 CH6* SDO 6 17 CH7* V CC LTC2424/LTC2428 8 = INTERNAL OSC/50Hz REJECTION 5ZS SET 26 = EXTERNAL CLOCK SOURCE 10 F GND O = INTERNAL OSC/60Hz REJECTION 0 0.5 1.0 1.5 2.0 2.5 1, 6, 16, 18, 22, 27, 28 24248 TA01 INPUT VOLTAGE (V) *THESE PINS ARE NO CONNECTS ON THE LTC2404 24248 G01 1 ERROR (ppm) U DS ULTC2424/LTC2428 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) LTC2424C/LTC2428C .............................. 0 C to 70 C CC Reference Input Voltage to GND .. 0.3V to (V + 0.3V) LTC2424I/LTC2428I ........................... 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 PACKAGE/ORDER INFORMATION TOP VIEW ORDER TOP VIEW ORDER PART NUMBER PART NUMBER 1 28 GND 1 28 GND GND GND 2 27 GND 2 27 GND V V CC CC LTC2424CG LTC2428CG 3 26 F 3 26 F FS O FS O SET SET LTC2424IG LTC2428IG 4 25 SCK 4 25 SCK ADCIN ADCIN 5 24 SDO 5 24 SDO ZS ZS SET SET GND 6 23 CSADC GND 6 23 CSADC MUXOUT 7 22 GND MUXOUT 7 22 GND V 8 21 D V 8 21 D IN IN CC CC CH0 9 20 CSMUX CH0 9 20 CSMUX CH1 10 19 CLK CH1 10 19 CLK CH2 11 18 GND CH2 11 18 GND CH3 12 17 NC CH3 12 17 CH7 NC 13 16 GND CH4 13 16 GND NC 14 15 NC CH5 14 15 CH6 G PACKAGE G PACKAGE 28-LEAD PLASTIC SSOP 28-LEAD PLASTIC SSOP T = 125 C, q = 130 C/W T = 125 C, q = 130 C/W JMAX JA JMAX JA 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. (Notes 3, 4) A PARAMETER CONDITIONS MIN TYP MAX UNITS Resolution (No Missing Codes) 0.1V V V , (Note 5) l 20 Bits REF CC Integral Nonlinearity V = 2.5V (Note 6) l 4 10 ppm of V REF REF V = 5V (Note 6) l 8 20 ppm of V REF REF Integral Nonlinearity (Fast Mode) 2.5V < V < V , 100 Samples/Second, f = 2.051MHz l 40 250 ppm of V REF CC O REF Offset Error 2.5V V V l 0.5 10 ppm of V REF CC REF Offset Error (Fast Mode) 2.5V < V < 5V, 100 Samples/Second, f = 2.051MHz 3 ppm of V REF O REF Offset Error Drift 2.5V V V 0.04 ppm of V / C REF CC REF Full-Scale Error 2.5V V V l 4 15 ppm of V REF CC REF Full-Scale Error (Fast Mode) 2.5V < V < 5V, 100 Samples/Second, f = 2.051MHz 10 ppm of V REF O REF Full-Scale Error Drift 2.5V V V 0.04 ppm of V / C REF CC REF 2 U U W U U WWW