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LTC2412 2-Channel Differential Input 24-Bit No Latency ∆Σ ADC
FEATURES
s s s
DESCRIPTIO
s s s s
s
s s s
2-Channel Differential Input with Automatic Channel Selection (Ping-Pong) Low Supply Current: 200µA, 4µA in Autosleep Differential Input and Differential Reference with GND to VCC Common Mode Range 2ppm INL, No Missing Codes 2.5ppm Full-Scale Error and 0.1ppm Offset 0.16ppm Noise, 22.5 Effective Number of Bits No Latency: Digital Filter Settles in a Single Cycle and Each Channel Conversion is Accurate Internal Oscillator—No External Components Required 110dB Min, 50Hz or 60Hz Notch Filter Narrow SSOP-16 Package Single Supply 2.7V to 5.5V Operation
The LTC®2412 is a 2-channel differential input micropower 24-bit No Latency ∆ΣTM analog-to-digital converter with an integrated oscillator. It provides 2ppm INL and 0.16ppm RMS noise over the entire supply range. The two differential channels are converted alternately with channel ID included in the conversion results. It uses delta-sigma technology and provides single conversion settling of the digital filter. Through a single pin, the LTC2412 can be configured for better than 110dB input differential mode rejection at 50Hz or 60Hz ±2%, or it can be driven by an external oscillator for a user defined rejection frequency. The internal oscillator requires no external frequency setting components. The converter accepts any external differential reference voltage from 0.1V to VCC for flexible ratiometric and remote sensing measurement configurations. The fullscale differential input range is from – 0.5VREF to 0.5VREF. The reference common mode voltage, VREFCM, and the input common mode voltage, VINCM, may be independently set anywhere within the GND to VCC. The DC common mode input rejection is better than 140dB. The LTC2412 communicates through a flexible 3-wire digital interface which is compatible with SPI and MICROWIRETM protocols.
, LTC and LT are registered trademarks of Linear Technology Corporation. No Latency ∆Σ is a trademark of Linear Technology Corporation. MICROWIRE is a trademark of National Semiconductor Corporation.
APPLICATIO S
s s s s s s s s s
Direct Sensor Digitizer Weight Scales Direct Temperature Measurement Gas Analyzers Strain-Gage Transducers Instrumentation Data Acquisition Industrial Process Control 6-Digit DVMs
TYPICAL APPLICATIO
2.7V TO 5.5V 1µF 1 2 4 VCC
1.5
VCC
FO
14
REF + CH0+ LTC2412 CH0– REF
–
TUE (ppm OF VREF)
= INTERNAL OSC/50Hz REJECTION = EXTERNAL CLOCK SOURCE = INTERNAL OSC/60Hz REJECTION
1.0 0.5 0 VCC = 5V REF+ = 5V REF– = GND VREF = 5V VINCM = 2.5V FO = GND TA = 90°C TA = 25°C TA = –45°C
5 THERMOCOUPLE 3 6 7 8, 9, 10, 15, 16
SCK SDO CS
13 12 11 3-WIRE SPI INTERFACE
–0.5 –1.0
CH1+ CH1– GND
2412 TA01
–1.5 –2.5 –2 –1.5 –1 –0.5 0 0.5 VIN (V)
U
Total Unadjusted Error vs Input
1 1.5 2 2.5
2412f
2412 TA02
U
U
1
LTC2412
ABSOLUTE
(Notes 1, 2)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW VCC REF + REF – CH0+ CH0– CH1+ CH1– GND 1 2 3 4 5 6 7 8 16 GND 15 GND 14 FO 13 SCK 12 SDO 11 CS 10 GND 9 GND
Supply Voltage (VCC) to GND .......................– 0.3V to 7V Analog Input Voltage to GND .................................... – 0.3V to (VCC + 0.3V) Reference Input Voltage to GND .................................... – 0.3V to (VCC + 0.3V) Digital Input Voltage to GND ........ – 0.3V to (VCC + 0.3V) Digital Output Voltage to GND ..... – 0.3V to (VCC + 0.3V) Operating Temperature Range LTC2412C ............................................... 0°C to 70°C LTC2412I ............................................ – 40°C to 85°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART NUMBER LTC2412CGN LTC2412IGN
GN PART MARKING 2412 2412I
GN PACKAGE 16-LEAD PLASTIC SSOP TJMAX = 125°C, θJA = 110°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The q denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Notes 3, 4)
PARAMETER Resolution (No Missing Codes) Integral Nonlinearity CONDITIONS 0.1V ≤ VREF ≤ VCC, –0.5 • VREF ≤ VIN ≤ 0.5 • VREF, (Note 5)
q
ELECTRICAL CHARACTERISTICS
MIN 24
TYP 1 2 5 0.5 10
MAX
UNITS Bits ppm of VREF ppm of VREF ppm of VREF µV nV/°C
5V ≤ VCC ≤ 5.5V, REF+ = 2.5V, REF– = GND, VINCM = 1.25V, (Note 6) 5V ≤ VCC ≤ 5.5V, REF+ = 5V, REF– = GND, VINCM = 2.5V, (Note 6) q REF+ = 2.5V, REF– = GND, VINCM = 1.25V, (Note 6) 2.5V ≤ REF+ ≤ VCC, REF– = GND, GND ≤ IN+ = IN– ≤ VCC, (Note 14) 2.5V ≤ REF+ ≤ VCC, REF– = GND, GND ≤ IN+ = IN– ≤ VCC 2.5V ≤ REF+ ≤ VCC, REF– = GND, IN+ = 0.75REF+, IN– = 0.25 • REF+ 2.5V ≤ REF+ ≤ VCC, REF– = GND, IN+ = 0.75REF+, IN– = 0.25 • REF+ 2.5V ≤ REF+ ≤ VCC, REF– = GND, IN+ = 0.25 • REF+, IN– = 0.75 • REF+ 2.5V ≤ REF+ ≤ VCC, REF– = GND, IN+ = 0.25 • REF+, IN– = 0.75 • REF+ 5V ≤ VCC ≤ 5.5V, REF+ = 2.5V, REF– = GND, VINCM = 1.25V 5V ≤ VCC ≤ 5.5V, REF+ = 5V, REF– = GND, VINCM = 2.5V REF+ = 2.5V, REF– = GND, VINCM = 1.25V, (Note 6) 5V ≤ VCC ≤ 5.5V, REF+ = 5V, REF – = GND, GND ≤ IN– = IN+ ≤ VCC, (Note 13)
q q q
14 2.5
Offset Error Offset Error Drift Positive Full-Scale Error Positive Full-Scale Error Drift Negative Full-Scale Error Negative Full-Scale Error Drift Total Unadjusted Error
2.5 0.03 2.5 0.03 3 3 4 0.8
12
ppm of VREF ppm of VREF/°C
12
ppm of VREF ppm of VREF/°C ppm of VREF ppm of VREF ppm of VREF µVRMS
Output Noise
2
U
2412f
W
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U
W W
W
LTC2412
CO VERTER CHARACTERISTICS
PARAMETER Input Common Mode Rejection DC Input Common Mode Rejection 60Hz ±2% Input Common Mode Rejection 50Hz ±2% Input Normal Mode Rejection 60Hz ±2% Input Normal Mode Rejection 50Hz ±2% Reference Common Mode Rejection DC Power Supply Rejection, DC Power Supply Rejection, 60Hz ±2% CONDITIONS
– 2.5V CC, REF = GND, GND ≤ IN– = IN+ ≤ VCC (Note 5) 2.5V ≤ REF+ ≤ VCC, REF– = GND, GND ≤ IN – = IN+ ≤ VCC, (Notes 5, 7) 2.5V ≤ REF+ ≤ VCC, REF– = GND, GND ≤ IN – = IN+ ≤ VCC, (Notes 5, 8)
The q denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Notes 3, 4)
MIN
q q q q q q
Power Supply Rejection, 50Hz ±2% REF+ = 2.5V, REF– = GND, IN– = IN+ = GND, (Note 8)
A ALOG I PUT A D REFERE CE The q denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. (Note 3)
SYMBOL IN+ IN– VIN REF+ REF– VREF CS (IN+) CS (IN–) CS CS (REF+) (REF–) (IN+) (REF+) PARAMETER Absolute/Common Mode IN+ Voltage Absolute/Common Mode IN– Voltage Input Differential Voltage Range (IN+ – IN–) Absolute/Common Mode REF+ Voltage Absolute/Common Mode REF– Voltage Reference Differential Voltage Range (REF+ – REF–) IN+ Sampling Capacitance IN– Sampling Capacitance REF+ Sampling Capacitance REF– Sampling Capacitance IN+ DC Leakage Current CS = VCC CS = VCC = 5.5V, IN+ = GND = 5.5V, REF+ = 5.5V
q q q q
IDC_LEAK IDC_LEAK
IDC_LEAK (IN–) IDC_LEAK (REF–)
IN– DC Leakage Current REF+ DC Leakage Current REF– DC Leakage Current
U
U
U
U
TYP 140
MAX
UNITS dB dB dB
≤ REF+ ≤ V
130 140 140 110 110 130
(Notes 5, 7) (Note 5, 8) 2.5V ≤ REF+ ≤ VCC, GND ≤ REF– ≤ 2.5V, VREF = 2.5V, IN– = IN+ = GND (Note 5) REF+ = 2.5V, REF– = GND, IN– = IN+ = GND REF+ = 2.5V, REF– = GND, IN– = IN+ = GND, (Note 7)
140 140 140 120 120 120
dB dB dB dB dB dB
U
CONDITIONS
q q q q q q
MIN GND – 0.3 GND – 0.3 –VREF/2 0.1 GND 0.1
TYP
MAX VCC + 0.3 VCC + 0.3 VREF/2 VCC VCC – 0.1 VCC
UNITS V V V V V V pF pF pF pF
18 18 18 18 –10 –10 –10 –10 1 1 1 1 10 10 10 10 CS = VCC = 5.5V, IN – = 5.5V CS = VCC = 5.5V, REF – = GND
nA nA nA nA
2412f
3
LTC2412
DIGITAL I PUTS A D DIGITAL OUTPUTS
SYMBOL VIH VIL VIH VIL IIN IIN CIN CIN VOH VOL VOH VOL IOZ PARAMETER High Level Input Voltage CS, FO Low Level Input Voltage CS, FO High Level Input Voltage SCK Low Level Input Voltage SCK Digital Input Current CS, FO Digital Input Current SCK Digital Input Capacitance CS, FO Digital Input Capacitance SCK High Level Output Voltage SDO Low Level Output Voltage SDO High Level Output Voltage SCK Low Level Output Voltage SCK Hi-Z Output Leakage SDO (Note 9) IO = –800µA IO = 1.6mA IO = –800µA (Note 10) IO = 1.6mA (Note 10)
q q q q q
The q denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 3)
CONDITIONS 2.7V ≤ VCC ≤ 5.5V 2.7V ≤ VCC ≤ 3.3V 4.5V ≤ VCC ≤ 5.5V 2.7V ≤ VCC ≤ 5.5V 2.7V ≤ VCC ≤ 5.5V (Note 9) 2.7V ≤ VCC ≤ 3.3V (Note 9) 4.5V ≤ VCC ≤ 5.5V (Note 9) 2.7V ≤ VCC ≤ 5.5V (Note 9) 0V ≤ VIN ≤ VCC 0V ≤ VIN ≤ VCC (Note 9)
q q q q q q
POWER REQUIRE E TS
SYMBOL VCC ICC PARAMETER Supply Voltage Supply Current Conversion Mode Sleep Mode Sleep Mode
The q denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 3)
CONDITIONS
q
4
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MIN 2.5 2.0
TYP
MAX
UNITS V V
0.8 0.6 2.5 2.0 0.8 0.6 –10 –10 10 10 VCC – 0.5 0.4 VCC – 0.5 0.4 –10 10 10 10
V V V V V V µA µA pF pF V V V V µA
MIN 2.7
TYP
MAX 5.5
UNITS V µA µA µA
CS = 0V CS = VCC (Note 12) CS = VCC, 2.7V ≤ VCC ≤ 3.3V (Note 12)
q q
200 4 2
300 13
2412f
LTC2412
TI I G CHARACTERISTICS
SYMBOL fEOSC tHEO tLEO tCONV PARAMETER External Oscillator Frequency Range External Oscillator High Period External Oscillator Low Period Conversion Time FO = 0V FO = VCC External Oscillator (Note 11) Internal Oscillator (Note 10) External Oscillator (Notes 10, 11) (Note 10) (Note 9) (Note 9) (Note 9) Internal Oscillator (Notes 10, 12) External Oscillator (Notes 10, 11) (Note 9)
q q q q q
