Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsData collecting ICsData acquisition IC - AD converter (ADC) External SOIC 8

LTC1860/LTC1861

18601fa

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

µPower, 12-Bit, 250ksps

1- and 2-Channel ADCs in MSOP

The LTC

1860/LTC1861 are 12-bit A/D converters that are

offered in MSOP and SO-8 packages and operate on a single

5V supply. At 250ksps, the supply current is only 850μA.

The supply current drops at lower speeds because the

LTC1860/LTC1861 automatically power down to a typical

supply current of 1nA between conversions. These 12-bit

switched capacitor successive approximation ADCs include

sample-and-holds. The LTC1860 has a differential analog

input with an adjustable reference pin. The LTC1861 offers

a software-selectable 2-channel MUX and an adjustable

reference pin on the MSOP version.

The 3-wire, serial I/O, MSOP or SO-8 package and

extremely high sample rate-to-power ratio make these

ADCs ideal choices for compact, low power, high speed

systems.

These ADCs can be used in ratiometric applications or

with external references. The high impedance analog in-

puts and the ability to operate with reduced spans down

to 1V full scale, allow direct connection to signal sources

in many applications, eliminating the need for external

gain stages.

Single 5V Supply, 250ksps, 12-Bit Sampling ADC

12-Bit 250ksps ADCs in MSOP Package

Single 5V Supply

Low Supply Current: 850μA (Typ)

Auto Shutdown Reduces Supply Current

to 2μA at 1ksps

True Differential Inputs

1-Channel (LTC1860) or 2-Channel (LTC1861)

Versions

SPI/MICROWIRE

Compatible Serial I/O

High Speed Upgrade to LTC1286/LTC1298

Pin Compatible with 16-Bit LTC1864/LTC1865

Guaranteed Operation to 125°C (MSOP Package)

High Speed Data Acquisition

Portable or Compact Instrumentation

Low Power Battery-Operated Instrumentation

Isolated and/or Remote Data Acquisition

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.

All other trademarks are the property of their respective owners.

Supply Current vs Sampling Frequency

REF

–

GND

SCK

SDO

CONV

LTC1860

1860 TA01

ANALOG INPUT

0V TO 5V

1MF

SERIAL DATA LINK TO

ASIC, PLD, MPU, DSP

OR SHIFT REGISTERS

SAMPLING FREQUENCY (kHz)

0.01

SUPPLY CURRENT (MA)

1000

100

0.1

0.01

100

1860 TA02

0.1

1000

Summary of content (16 pages)

PAGE 1
LTC1860/LTC1861 µPower, 12-Bit, 250ksps 1- and 2-Channel ADCs in MSOP FEATURES DESCRIPTION n The LTC®1860/LTC1861 are 12-bit A/D converters that are offered in MSOP and SO-8 packages and operate on a single 5V supply. At 250ksps, the supply current is only 850μA. The supply current drops at lower speeds because the LTC1860/LTC1861 automatically power down to a typical supply current of 1nA between conversions. These 12-bit switched capacitor successive approximation ADCs include sample-and-holds.
PAGE 2
LTC1860/LTC1861 ABSOLUTE MAXIMUM RATINGS (Notes 1, 2) Supply Voltage (VCC) .................................................7V Ground Voltage Difference AGND, DGND LTC1861 MSOP Package .............±0.3V Analog Input ....................(GND – 0.3V) to (VCC + 0.3V) Digital Input .................................... (GND – 0.3V) to 7V Digital Output ................... (GND – 0.3V) to (VCC + 0.3V) Power Dissipation ..............................................
PAGE 3
LTC1860/LTC1861 ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC1860CMS8#PBF LTC1860CMS8#TRPBF LTWR 8-Lead Plastic MSOP 0°C to 70°C LTC1860IMS8#PBF LTC1860IMS8#PBF LTWS 8-Lead Plastic MSOP –40°C to 85°C LTC1860HMS8#PBF LTC1860HMS8#PBF LTWS 8-Lead Plastic MSOP –40°C to 125°C LTC1860CS8#PBF LTC1860CS8#PBF 1860 8-Lead Plastic SO 0°C to 70°C LTC1860IS8#PBF LTC1860IS8#PBF 1860I 8-Lead Plastic SO –40°C to 85°C LTC1861CMS#PBF LTC
PAGE 4
LTC1860/LTC1861 CONVERTER AND MULTIPLEXER CHARACTERISTICS The ● denotes speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are TA = 25°C. VCC = 5V, VREF = 5V, fSCK = fSCK(MAX) as deﬁned in Recommended Operating Conditions, unless otherwise noted. SYMBOL CONDITIONS MIN TYP MAX UNITS Resolution l 12 Bits No Missing Codes Resolution l 12 Bits INL l (Note 3) ±1 Transition Noise 0.
PAGE 5
LTC1860/LTC1861 DIGITAL AND DC ELECTRICAL CHARACTERISTICS The ● denotes speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are TA = 25°C. VCC = 5V, VREF = 5V, unless otherwise noted. SYMBOL PARAMETER CONDITIONS IOZ Hi-Z Output Leakage CONV = VCC ISOURCE Output Source Current VOUT = 0V –25 mA ISINK Output Sink Current VOUT = VCC 20 mA IREF Reference Current (LTC1860 SO-8, MSOP and LTC1861 MSOP) CONV = VCC fSMPL = fSMPL(MAX) l l 0.001 0.05 3 0.
PAGE 6
LTC1860/LTC1861 TIMING CHARACTERISTICS The ● denotes speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are TA = 25°C. VCC = 5V, VREF = 5V, fSCK = fSCK(MAX) as deﬁned in Recommended Operating Conditions, unless otherwise noted.
PAGE 7
LTC1860/LTC1861 TYPICAL PERFORMANCE CHARACTERISTICS Supply Current vs Sampling Frequency Supply Current vs Temperature CONV LOW = 800ns TA = 25oC VCC = 5V 1000 900 800 10 1 600 400 CONV HIGH = 3.2MS fSMPL = 250kHz VCC = 5V VREF = 5V 200 0.1 0.01 0.01 0.1 10 100 1.
PAGE 8
LTC1860/LTC1861 TYPICAL PERFORMANCE CHARACTERISTICS Change in Offset Error vs Reference Voltage CHANGE IN OFFSET ERROR (LSB) 1.0 TA = 25oC VCC = 5V 4 CHANGE IN OFFSET (LSB) 3 2 1 0 –1 –2 0.4 0.2 0 –0.2 –0.4 –0.6 –4 –0.8 1 0 3 4 2 REFERENCE VOLTAGE (V) –25 50 25 0 75 TEMPERATURE (oC) Change in Gain Error vs Temperature 0.4 0.2 0 –0.2 –0.4 –0.6 –0.
PAGE 9
LTC1860/LTC1861 PIN FUNCTIONS LTC1860 VREF (Pin 1): Reference Input. The reference input deﬁnes the span of the A/D converter and must be kept free of noise with respect to GND. SDI (Pin 6): Digital Data Input. The A/D conﬁguration word is shifted into this input. SDO (Pin 7): Digital Data Output. The A/D conversion result is shifted out of this output. IN +, IN– (Pins 2, 3): Analog Inputs. These inputs must be free of noise with respect to GND. SCK (Pin 8): Shift Clock Input.
PAGE 10
LTC1860/LTC1861 FUNCTIONAL BLOCK DIAGRAM CONV (SDI) SCK VCC PIN NAMES IN PARENTHESES REFER TO LTC1861 CONVERT CLK SDO SERIAL PORT BIAS AND SHUTDOWN DATA IN 12-BITS IN+ (CH0) + IN– (CH1) – 12-BIT SAMPLING ADC DATA OUT 1860/61 BD GND VREF TEST CIRCUITS Load Circuit for tdDO, tr, tf, tdis and ten Voltage Waveforms for SDO Rise and Fall Times, tr, tf TEST POINT VOH SDO VOL VCC tdis WAVEFORM 2, ten 3k SDO tr tdis WAVEFORM 1 20pF tf 1860 TC04 1860 TC01 Voltage Waveforms for ten Volta
PAGE 11
LTC1860/LTC1861 APPLICATIONS INFORMATION tsuCONV CONV tSMPL SLEEP MODE tCONV 1 2 3 4 5 6 7 8 9 10 11 12 SCK SDO B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0* Hi-Z Hi-Z *AFTER COMPLETING THE DATA TRANSFER, IF FURTHER Figure 1. LTC1860 Operating Sequence 1MF 111111111111 111111111110 VCC • • • LTC1860 1 000000000001 000000000000 VIN* VIN = 0V TO VCC VREF VREF – 1LSB VREF – 2LSB 1LSB 0V *VIN = IN+ – IN– Figure 2.
PAGE 12
LTC1860/LTC1861 APPLICATIONS INFORMATION CONV SDI tSMPL SLEEP MODE tCONV S/D O/S DON’T CARE 1 2 DON’T CARE 3 4 5 6 7 8 9 10 11 12 SCK SDO B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0* Hi-Z Hi-Z *AFTER COMPLETING THE DATA TRANSFER, IF FURTHER SCK CLOCKS ARE APPLIED WITH CONV LOW, THE ADC WILL OUTPUT ZEROS INDEFINITELY 1860 F04 Figure 4. LTC1861 Operating Sequence 111111111111 111111111110 • • • Table 1.
PAGE 13
LTC1860/LTC1861 APPLICATIONS INFORMATION Reference Input Bypassing The reference input of the LTC1861 SO-8 package is internally tied to VCC. The span of the A/D converter is therefore equal to VCC. The voltage on the reference input of the LTC1861 MSOP package deﬁnes the span of the A/D converter. The LTC1861 MSOP package can operate with reference voltages from 1V to VCC. For good performance, the VCC and VREF pins must be free of noise and ripple.
PAGE 14
LTC1860/LTC1861 PACKAGE DESCRIPTION MS8 Package 8-Lead Plastic MSOP (Reference LTC DWG # 05-08-1660) 3.00 p 0.102 (.118 p .004) (NOTE 3) 0.889 p 0.127 (.035 p .005) 5.23 (.206) MIN 3.20 – 3.45 (.126 – .136) 0.254 (.010) 8 7 6 5 3.00 p 0.102 (.118 p .004) (NOTE 4) 4.90 p 0.152 (.193 p .006) DETAIL “A” 0.52 (.0205) REF 0o – 6o TYP GAUGE PLANE 0.42 p 0.038 (.0165 p .0015) TYP 1 0.65 (.0256) BSC 0.53 p 0.152 (.021 p .006) DETAIL “A” RECOMMENDED SOLDER PAD LAYOUT 2 3 4 1.10 (.043) MAX 0.86 (.
PAGE 15
LTC1860/LTC1861 PACKAGE DESCRIPTION S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) .189 – .197 (4.801 – 5.004) NOTE 3 .045 p.005 .050 BSC 8 .245 MIN 7 6 5 .160 p.005 .150 – .157 (3.810 – 3.988) NOTE 3 .228 – .244 (5.791 – 6.197) .030 p.005 TYP 1 RECOMMENDED SOLDER PAD LAYOUT .010 – .020 s 45o (0.254 – 0.508) .008 – .010 (0.203 – 0.254) 3 4 .053 – .069 (1.346 – 1.752) .004 – .010 (0.101 – 0.254) 0o– 8o TYP .016 – .050 (0.406 – 1.270) NOTE: 1.
PAGE 16
LTC1860/LTC1861 TYPICAL APPLICATION Sample Two Channels Simultaneously with a Single Input ADC f1 (0V TO 0.66V) 5V 0.1MF + 4.096V REF 5k 4.096V REF 1007 1/2 LT1492 – 100pF 0.1MF 1MF 0.1MF 1MF 20k 8 VCC 28.7k 5pF 10k 10k 2 1MF 0.1MF f2 (0V TO 2V) IN– 5V 5k + 8 3 0.1MF 1/2 LT1492 – IN+ 4 1 REF 7 SCK 6 LTC1860 SDO 5 CONV GND 4 1007 100pF 1860 TA03 RELATED PARTS PART NUMBER SAMPLE RATE POWER DISSIPATION DESCRIPTION 12-Bit Serial I/o ADCs LTC1286/LTC1298 12.5ksps/11.