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LTC1863/LTC1867

18637fa

BLOCK DIAGRAM

DESCRIPTION

12-/16-Bit, 8-Channel

200ksps ADCs

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

trademarks are the property of their respective owners.

FEATURES

APPLICATIONS

Industrial Process Control

High Speed Data Acquisition

Battery Operated Systems

Multiplexed Data Acquisition Systems

Imaging Systems

Sample Rate: 200ksps

16-Bit No Missing Codes and ±2LSB Max INL

8-Channel Multiplexer with:

Single Ended or Differential Inputs and

Unipolar or Bipolar Conversion Modes

SPI/MICROWIRE™ Serial I/O

Signal-to-Noise Ratio: 89dB

Single 5V Operation

On-Chip or External Reference

Low Power: 1.3mA at 200ksps, 0.76mA at 100ksps

Sleep Mode

Automatic Nap Mode Between Conversions

16-Pin Narrow SSOP Package

The LTC

1863/LTC1867 are pin-compatible, 8-channel

12-/16-bit A/D converters with serial I/O, and an internal

reference. The ADCs typically draw only 1.3mA from a

single 5V supply.

The 8-channel input multiplexer can be conﬁ gured for

either single-ended or differential inputs and unipolar

or bipolar conversions (or combinations thereof). The

automatic nap and sleep modes beneﬁ t power sensitive

applications.

The LTC1867’s DC performance is outstanding with a

±2LSB INL speciﬁ cation and no missing codes over tem-

perature. The signal-to-noise ratio (SNR) for the LTC1867

is typically 89dB, with the internal reference.

Housed in a compact, narrow 16-pin SSOP package, the

LTC1863/LTC1867 can be used in space-sensitive as well

as low-power applications.

CH0

CH1

CH2

CH3

CH4

CH5

CH6

CH7/COM

GND

SDI

SDO

SCK

CS/CONV

REF

18637 BD

12-/16-BIT

200ksps

ADC

–

SERIAL

PORT

ANALOG

INPUT

MUX

REFCOMP

INTERNAL

2.5V REF

LTC1863/LTC1867

OUTPUT CODE

INL (LSB)

49152

18637 GO1

16384 32768 65536

2.0

1.5

1.0

0.5

–0.5

–1.0

–1.5

–2.0

Integral Nonlinearity vs Output Code

(LTC1867)

Summary of content (16 pages)

PAGE 1
LTC1863/LTC1867 12-/16-Bit, 8-Channel 200ksps ADCs FEATURES DESCRIPTION n The LTC®1863/LTC1867 are pin-compatible, 8-channel 12-/16-bit A/D converters with serial I/O, and an internal reference. The ADCs typically draw only 1.3mA from a single 5V supply.
PAGE 2
LTC1863/LTC1867 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1, 2) Supply Voltage (VDD) ................................... –0.3V to 6V Analog Input Voltage CH0-CH7/COM (Note 3) ...........– 0.3V to (VDD + 0.3V) VREF, REFCOMP (Note 4) ......... –0.3V to (VDD + 0.3V) Digital Input Voltage (SDI, SCK, CS/CONV) (Note 4) ................................................. –0.3V to 10V Digital Output Voltage (SDO) ....... –0.3V to (VDD + 0.3V) Power Dissipation ..............................................
PAGE 3
LTC1863/LTC1867 CONVERTER CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. With external reference (Notes 5, 6) LTC1863 PARAMETER CONDITIONS MIN TYP Gain Error Match LTC1867 MAX MIN TYP ±1 LTC1867A MAX MIN TYP ±4 UNITS ±2 Gain Error Tempco Internal Reference External Reference ±15 ±2.7 ±15 ±2.7 ±15 ±2.7 Power Supply Sensitivity VDD = 4.75V – 5.
PAGE 4
LTC1863/LTC1867 DIGITAL INPUTS AND DIGITAL OUTPUTS The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C.
PAGE 5
LTC1863/LTC1867 TIMING CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. (Note 5) Note 4: When these pin voltages are taken below GND, they will be clamped by internal diodes. This product can handle input currents of greater than 100mA below GND without latchup. These pins are not clamped to VDD. Note 5: VDD = 5V, fSAMPLE = 200ksps at 25°C, t r = tf = 5ns and VIN– = 2.
PAGE 6
LTC1863/LTC1867 TYPICAL PERFORMANCE CHARACTERISTICS (LTC1867) Signal-to-(Noise + Distortion) vs Input Frequency Total Harmonic Distortion vs Input Frequency 100 –20 90 90 –30 80 80 –40 70 60 50 AMPLITUDE (dB) 100 AMPLITUDE (dB) AMPLITUDE (dB) Signal-to-Noise Ratio vs Frequency 70 60 50 –50 –60 –70 40 40 –80 30 30 –90 20 20 1 10 INPUT FREQUENCY (kHz) –100 1 100 10 INPUT FREQUENCY (kHz) 1 100 10 INPUT FREQUENCY (kHz) 18637 G08 18637 G07 100 18637 G09 (LTC1863/LTC1867) Suppl
PAGE 7
LTC1863/LTC1867 PIN FUNCTIONS CHO-CH7/COM (Pins 1-8): Analog Input Pins. Analog inputs must be free of noise with respect to GND. CH7/COM can be either a separate channel or the common minus input for the other channels. REFCOMP (Pin 9): Reference Buffer Output Pin. Bypass to GND with 10μF tantalum capacitor in parallel with 0.1μF ceramic capacitor (4.096V Nominal). To overdrive REFCOMP, tie VREF to GND. VREF (Pin 10): 2.5V Reference Output.
PAGE 8
LTC1863/LTC1867 TIMING DIAGRAMS t1 (For Short Pulse Mode) t2 (SDO Valid Before SCK↑), t3 (SDO Valid Hold Time After SCK↓) t1 CS/CONV t2 50% 50% SCK 0.4V t3 2.4V 0.4V SDO t5 (SDI Setup Time Before SCK↑), t6 (SDI Hold Time After SCK↑) t4 (SDO Valid After CONV↓) t4 CS/CONV SDO 2.4V SCK 0.4V Hi-Z 2.4V 0.4V SDI t7 (SLEEP Mode Wake-Up Time) 2.4V 0.4V 2.4V 0.4V t8 (BUS Relinquish Time) t7 SCK t6 t5 t8 CS/CONV 50% 2.
PAGE 9
LTC1863/LTC1867 APPLICATIONS INFORMATION Changing the MUX Assignment “On the Fly” Analog Input Multiplexer 1st Conversion The analog input multiplexer is controlled by a 7-bit input data word.
PAGE 10
LTC1863/LTC1867 APPLICATIONS INFORMATION Driving the Analog Inputs The analog inputs of the LTC1863/LTC1867 are easy to drive. Each of the analog inputs can be used as a singleended input relative to the GND pin (CH0-GND, CH1-GND, etc) or in pairs (CH0 and CH1, CH2 and CH3, CH4 and CH5, CH6 and CH7) for differential inputs. In addition, CH7 can act as a COM pin for both single-ended and differential modes if the COM bit in the input word is high.
PAGE 11
LTC1863/LTC1867 APPLICATIONS INFORMATION Dynamic Performance 50Ω ANALOG INPUT CH0 LTC1863/ LTC1867 2000pF GND REFCOMP 10μF 1867 F01a Figure 1a. Optional RC Input Filtering for Single-Ended Input 1000pF 50Ω CH0 DIFFERENTIAL ANALOG INPUTS LTC1863/ LTC1867 1000pF 50Ω CH1 1000pF REFCOMP 10μF 1867 F01b FFT (Fast Fourier Transform) test techniques are used to test the ADC’s frequency response, distortion and noise at the rated throughput.
PAGE 12
LTC1863/LTC1867 APPLICATIONS INFORMATION where V1 is the RMS amplitude of the fundamental frequency and V2 through VN are the amplitudes of the second through Nth harmonics. Internal Reference The LTC1863/LTC1867 has an on-chip, temperature compensated, curvature corrected, bandgap reference that is factory trimmed to 2.5V. It is internally connected to a reference ampliﬁer and is available at VREF (Pin 10).
PAGE 13
LTC1863/LTC1867 APPLICATIONS INFORMATION If the CS/CONV returns low during a bit decision, it can create a small error. For best performance ensure that the CS/CONV returns low either within 100ns after the conversion starts (i.e. before the ﬁrst bit decision) or after the conversion ends. If CS/CONV is low when the conversion ends, the MSB bit will appear on SDO at the end of the conversion and the ADC will remain powered up. sential to the low noise operation of the ADC.
PAGE 14
LTC1863/LTC1867 APPLICATIONS INFORMATION CS/CONV tACQ NOT NEEDED FOR LTC1863 SCK SDI DON'T CARE 1 2 3 4 5 6 7 COM UNI SLP 8 9 10 11 12 SD 0S S1 S0 MSB = D11 D10 D9 D8 D6 D5 D4 D3 D2 D1 D0 MSB = D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 13 14 15 DON'T CARE 16 DON'T CARE tCONV SDO (LTC1863) SDO (LTC1867) Hi-Z D7 tCONV D3 D2 D1 D0 Hi-Z 1867 F07 111...111 011...111 BIPOLAR ZERO 011...110 111...110 OUTPUT CODE OUTPUT CODE (TWO’S COMPLIMENT) Figure 7.
PAGE 15
LTC1863/LTC1867 PACKAGE DESCRIPTION GN Package 16-Lead Plastic SSOP (Narrow .150 Inch) (Reference LTC DWG # 05-08-1641) .189 – .196* (4.801 – 4.978) .045 ±.005 16 15 14 13 12 11 10 9 .254 MIN .009 (0.229) REF .150 – .165 .229 – .244 (5.817 – 6.198) .0165 ±.0015 .150 – .157** (3.810 – 3.988) .0250 BSC RECOMMENDED SOLDER PAD LAYOUT 1 .015 ± .004 × 45° (0.38 ± 0.10) .007 – .0098 (0.178 – 0.249) 2 3 4 5 6 7 .0532 – .0688 (1.35 – 1.75) 8 .004 – .0098 (0.102 – 0.249) 0° – 8° TYP .016 – .
PAGE 16
LTC1863/LTC1867 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1417 14-Bit, 400ksps Serial ADC 20mW, Unipolar or Bipolar, Internal Reference, SSOP-16 Package LT1460 Micropower Precision Series Reference Bandgap, 130μA Supply Current, 10ppm/°C, SOT-23 Package LT1468/LT1469 Single/Dual 90MHz, 22V/μs, 16-Bit Accurate Op Amps Low Input Offset: 75μV/125μV LTC1609 16-Bit, 200ksps Serial ADC 65mW, Conﬁgurable Bipolar and Unipolar Input Ranges, 5V Supply LT1790 Micropower Low Dropout Reference 60