LTC1860/LTC1861 – µPower, 12-Bit, 250ksps 1- and 2-Channel ...

[Pages:18]LTC1860/LTC1861

?Power, 12-Bit, 250ksps 1- and 2-Channel ADCs in MSOP

Features

nn 12-Bit 250ksps ADCs in MSOP Package nn Single 5V Supply nn Low Supply Current: 850?A (Typ) nn Auto Shutdown Reduces Supply Current

to 2?A at 1ksps nn True Differential Inputs nn 1-Channel (LTC1860) or 2-Channel (LTC1861)

Versions nn SPI/MICROWIRETM Compatible Serial I/O nn High Speed Upgrade to LTC1286/LTC1298 nn Pin Compatible with 16-Bit LTC1864/LTC1865 nn Guaranteed Operation to 125?C (MSOP Package)

Applications

nn High Speed Data Acquisition nn Portable or Compact Instrumentation nn Low Power Battery-Operated Instrumentation nn Isolated and/or Remote Data Acquisition

Description

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 850?A. 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 inputs 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.

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.

Typical Application

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

1?F 5V

ANALOG INPUT 0V TO 5V

LTC1860

1 VREF

2 IN+

8 VCC

7 SCK

3 IN?

6 SDO

4 GND CONV 5

1860 TA01

SERIAL DATA LINK TO ASIC, PLD, MPU, DSP OR SHIFT REGISTERS

SUPPLY CURRENT (?A)

Supply Current vs Sampling Frequency

1000

100

10

1

0.1

0.01 0.01

0.1

1

10 100

SAMPLING FREQUENCY (kHz)

1000

1860 TA02

For more information LTC1860

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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............................................... 400mW Operating Temperature Range

LTC1860C/LTC1861C................................0?C to 70?C LTC1860I/LTC1861I ........................... ? 40?C to 85?C LTC1860H/LTC1861H..........................?40?C to 125?C Storage Temperature Range....................?65?C to 150?C Lead Temperature (Soldering, 10 sec)...................300?C

Pin Configuration

LTC1860 LTC1860

TOP VIEW

VRINE+F

1 2

IN? 3

GND 4

8 VCC 7 SCK

6 SDO

5 CONV

MS8 PACKAGE 8-LEAD PLASTIC MSOP

TJMAX = 150?C, JA = 210?C/W

TOP VIEW

VREF 1 IN+ 2 IN? 3

GND 4

8 VCC 7 SCK 6 SDO 5 CONV

S8 PACKAGE 8-LEAD PLASTIC SO

TJMAX = 150?C, JA = 175?C/W

LTC1861 LTC1861

CONV 1 CH0 2 CH1 3

AGND 4 DGND 5

TOP VIEW

10 VREF 9 VCC 8 SCK 7 SDO 6 SDI

MS PACKAGE 10-LEAD PLASTIC MSOP

TJMAX = 150?C, JA = 210?C/W

TOP VIEW

CONV 1 CH0 2 CH1 3 GND 4

8 VCC 7 SCK 6 SDO 5 SDI

S8 PACKAGE 8-LEAD PLASTIC SO

TJMAX = 150?C, JA = 175?C/W

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For more information LTC1860

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#TRPBF LTWS

8-Lead Plastic MSOP

?40?C to 85?C

LTC1860HMS8#PBF

LTC1860HMS8#TRPBF LTWS

8-Lead Plastic MSOP

?40?C to 125?C

LTC1860CS8#PBF

LTC1860CS8#TRPBF

1860

8-Lead Plastic SO

0?C to 70?C

LTC1860IS8#PBF

LTC1860IS8#TRPBF

1860I

8-Lead Plastic SO

?40?C to 85?C

LTC1861CMS#PBF

LTC1861CMS#TRPBF LTWT

10-Lead Plastic MSOP

0?C to 70?C

LTC1861IMS#PBF

LTC1861IMS#TRPBF

LTWU

10-Lead Plastic MSOP

?40?C to 85?C

LTC1861HMS#PBF

LTC1861HMS#TRPBF LTWU

10-Lead Plastic MSOP

?40?C to 125?C

LTC1861CS8#PBF

LTC1861CS8#TRPBF

1861

8-Lead Plastic SO

0?C to 70?C

LTC1861IS8#PBF

LTC1861IS8#TRPBF

1861I

8-Lead Plastic SO

?40?C to 85?C

Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.

For more information on lead free part marking, go to: For more information on tape and reel specifications, go to: . Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.

For more information LTC1860

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LTC1860/LTC1861

CONVERTER AND MULTIPLEXER CHARACTERISTICS

The l 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

(Note 3)

l

?1

LSB

Transition Noise Gain Error

0.07

LSBRMS

l

?20

mV

Offset Error Input Differential Voltage Range Absolute Input Range VREF Input Range

LTC1860 SO-8 and MSOP, LTC1861 MSOP LTC1861 SO-8 VIN = IN+ ? IN? IN+ Input IN? Input

LTC1860 SO-8 and MSOP, LTC1861 MSOP

l

?2

?5

mV

l

?3

?7

mV

l

0

VREF

V

?0.05 ?0.05

1

VCC + 0.05

V

VCC/2

V

VCC

V

Analog Input Leakage Current (Note 4)

l

?1

?A

CIN Input Capacitance

In Sample Mode During Conversion

12

pF

5

pF

dynamic accuracy

TA = 25?C. VCC = 5V, fSAMPLE = 250kHz, unless otherwise specified.

SYMBOL SNR S/(N + D) THD

PARAMETER Signal-to-Noise Ratio Signal-to-Noise Plus Distortion Ratio Total Hamonic Distortion Up to 5th Harmonic Full Power Bandwidth Full Linear Bandwidth

CONDITIONS

100kHz Input Signal 100kHz Input Signal

S/(N + D) 68dB

MIN TYP MAX UNITS

72

dB

71

dB

77

dB

20

MHz

125

kHz

digital and dc electrical characteristics The l 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

MIN TYP MAX UNITS

VIH

High Level Input Voltage

VCC = 5.25V

l 2.4

V

VIL

Low Level Input Voltage

VCC = 4.75V

l

0.8

V

IIH

High Level Input Current

VIN = VCC

l

2.5

?A

IIL

Low Level Input Current

VIN = 0V

l

?2.5

?A

VOH

High Level Output Voltage

VCC = 4.75V, IO = 10?A

VCC = 4.75V, IO = 360?A

VOL

Low Level Output Voltage

VCC = 4.75V, IO = 1.6mA

l 4.5

4.74

V

l 2.4

4.72

V

l

0.4

V

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LTC1860/LTC1861

digital and dc electrical characteristics The l denotes specifications which apply

over the full operating temperature range, otherwise specifications are TA = 25?C. VCC = 5V, VREF = 5V, unless otherwise noted.

SYMBOL IOZ ISOURCE ISINK IREF

ICC

PD

PARAMETER Hi-Z Output Leakage Output Source Current Output Sink Current Reference Current (LTC1860 SO-8, MSOP and LTC1861 MSOP) Supply Current

Power Dissipation

CONDITIONS CONV = VCC VOUT = 0V VOUT = VCC CONV = VCC fSMPL = fSMPL(MAX) CONV = VCC After Conversion CONV = VCC After Conversion, H-Grade fSMPL = fSMPL(MAX) fSMPL = fSMPL(MAX)

MIN TYP MAX UNITS

l

?3

?A

?25

mA

20

mA

l

0.001

3

?A

l

0.05

0.1

mA

l

0.001

3

?A

l

0.001

5

?A

l

0.85

1.3

mA

1.25

mV

recommended operating conditions The l denotes specifications which apply over

the full operating temperature range, otherwise specifications are TA = 25?C.

SYMBOL VCC fSCK

tCYC tSMPL

tsuCONV

thDI tsuDI tWHCLK tWLCLK tWHCONV

tWLCONV thCONV

PARAMETER Supply Voltage Clock Frequency

Total Cycle Time Analog Input Sampling Time

Setup Time CONV Before First SCK, (See Figure 1) Holdtime SDI After SCK Setup Time SDI Stable Before SCK SCK High Time SCK Low Time CONV High Time Between Data Transfer Cycles CONV Low Time During Data Transfer Hold Time CONV Low After Last SCK

CONDITIONS

H-Grade

LTC1860 (Note 5) LTC1861 (Note 5)

H-Grade LTC1861 LTC1861 fSCK = fSCK(MAX) fSCK = fSCK(MAX) (Note 5)

(Note 5)

MIN TYP MAX

4.75

5.25

l

20

l

16.7

12 ? SCK + tCONV

12 10

60

30

65

30

15

15

40%

40%

tCONV

12 13

UNITS V

MHz MHz

?s SCK SCK

ns ns ns ns 1/fSCK 1/fSCK ?s

SCK ns

For more information LTC1860

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LTC1860/LTC1861

timing characteristics The l 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 tCONV fSMPL(MAX) tdDO

tdis ten thDO tr tf

PARAMETER Conversion Time (See Figure 1)

Maximum Sampling Frequency

Delay Time, SCK to SDO Data Valid

Delay Time, CONV to SDO Hi-Z

Delay Time, CONV to SDO Enabled

Time Output Data Remains Valid After SCK SDO Rise Time SDO Fall Time

CONDITIONS

H-Grade

H-Grade CLOAD = 20pF CLOAD = 20pF CLOAD = 20pF, H-Grade

H-Grade CLOAD = 20pF CLOAD = 20pF, H-Grade CLOAD = 20pF

CLOAD = 20pF CLOAD = 20pF

MIN TYP MAX UNITS

l

2.75

3.2

?s

l

2.75

3.3

?s

l 250

kHz

l 248

kHz

15

20

ns

l

25

ns

l

30

ns

l

30

60

ns

l

30

65

ns

l

30

60

ns

l

30

65

ns

l

5

10

ns

8

ns

4

ns

Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime.

Note 2: All voltage values are with respect to GND.

Note 3: Integral nonlinearity is defined as deviation of a code from a straight line passing through the actual endpoints of the transfer curve. The deviation is measured from the center of the quantization band.

Note 4: Channel leakage current is measured while the part is in sample mode.

Note 5: Guaranteed by design, not subject to test.

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Typical Performance Characteristics

LTC1860/LTC1861

SUPPLY CURRENT (?A)

Supply Current vs Sampling Frequency

1000 100

CONV LOW = 800ns TA = 25?C VCC = 5V

10

1

0.1

0.01 0.01

0.1

1.0

10

100

SAMPLING FREQUENCY (kHz)

1000

1860/61 G01

Reference Current vs Sample Rate

60 CONV IS LOW FOR 800ns TA = 25?C

50 VCC = 5V VREF = 5V

40

30

20

10

0

0

50

100 150 200 250

SAMPLE RATE (kHz)

1860/61 G04

Typical INL Curve

1.0 TA = 25?C VCC = 5V VREF = 5V

0.5

REFERENCE CURRENT (?A)

SUPPLY CURRENT (?A)

Supply Current vs Temperature

1000

800

600

400

200

0 ?50 ?25

CONV HIGH = 3.2?S fSMPL = 250kHz VCC = 5V VREF = 5V

0 25 50 75 100 125 TEMPERATURE (?C)

1860/61 G02

Reference Current vs Temperature

55 fS = 250kHz 54 VCC = 5V 53 VREF = 5V

52

51

50

49

48

47

46

45 ?50 ?25

0 25 50 75 TEMPERATURE (?C)

100 125

1860/61 G05

Typical DNL Curve

1.0 TA = 25?C VCC = 5V VREF = 5V

0.5

IREF (?A)

SLEEP CURRENT (nA)

Sleep Current vs Temperature

1000 CONV = VCC = 5V

900

800

700

600

500

400

300

200

100

0 ?50 ?25

0 25 50 75 100 125 TEMPERATURE (?C)

1860/61 G03

Reference Current vs Reference Voltage

60 fS = 250kHz TA = 25?C

50 VCC = 5V

40

30

20

10

0

0

1

2

3

VREF (V)

4

5

1860/61 G06

Analog Input Leakage vs Temperature

100 VCC = 5V VREF = 5V CONV = 0V

75

REFERENCE CURRENT (?A)

ANALOG INPUT LEAKAGE (nA)

DNL EOC ERROR (LSBs)

INL COC ERROR (LSBs)

0

0

50

?0.5

?0.5

25

?1.0 0

512 1024 1536 2048 2560 3072 3584 4096 CODE

1860/61 G07

?1.0 0

512 1024 1536 2048 2560 3072 3584 4096 CODE

1860/61 G07

For more information LTC1860

0 ?50 ?25

0 25 50 75 TEMPERATURE (?C)

100 125

1860/61 G09

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LTC1860/LTC1861 Typical Performance Characteristics

CHANGE IN OFFSET ERROR (LSB)

CHANGE IN GAIN ERROR (LSB)

Change in Offset Error vs Reference Voltage

5

TA = 25?C

4

VCC = 5V

3

2

1

0

?1

?2

?3

?4

?5

0

1

2

3

4

5

REFERENCE VOLTAGE (V)

1860/61 G10

Change in Gain Error vs Temperature

1.0 VCC = 5V

0.8 VREF = 5V

0.6

0.4

0.2

0

?0.2

?0.4

?0.6

?0.8

?1.0 ?50 ?25

0 25 50 75 TEMPERATURE (?C)

100 125

1860/61 G13

Signal-to-(Noise + Distortion)

vs fIN

100 TA = 25?C

90 VCC = 5V 80 VIN = 0dB

70

SNR

60

50 SINAD

40

30

20

10

0

1

10

100

1000 10000

fIN (kHz)

1860/61 G16

TOTAL HARMONIC DISTORTION (dB)

SIGNAL-TO-(NOISE + DISTORTION) (dB)

CHANGE IN OFFSET (LSB)

Change in Offset vs Temperature

1.0 VCC = 5V

0.8

0.6

0.4

0.2

0

?0.2

?0.4

?0.6

?0.8

?1.0 ?50 ?25

0 25 50 75 100 125 TEMPERATURE (?C)

1860/61 G11

Signal-to-(Noise + Distortion) vs Input Level

80 fIN = 10kHz

70 TA = 25?C VCC = 5V

60

50

40

30

20

10

0 ?40 ?35 ?30 ?25 ?20 ?15 ?10 ?5 0

INPUT LEVEL (dB)

1195 G20

Total Harmonic Distortion

vs fIN

0

?10

TA = 25?C VCC = 5V

?20 VIN = 0dB

?30

?40

?50

?60

?70

?80

?90

?100 1

10

100

fIN (kHz)

1000

1860/61 G17

SIGNAL-TO-(NOISE + DISTORTION) (dB)

8

For more information LTC1860

SPURIOUS FREE DYNAMIC RANGE (dB)

AMPLITUDE (dB)

CHANGE IN GAIN ERROR (LSB)

Change in Gain Error vs Reference Voltage

5 VCC = 5V

4 TA = 25?C

3

2

1

0

?1

?2

?3

?4

?5

0

1

2

3

4

5

REFERENCE VOLTAGE(V)

1860/61 G12

4096 Point FFT

0 fS = 204.1kHz fIN = 99.5kHz

?20 TA = 25?C VCC = 5V

?40

?60

?80

?100

?120 0 10 20 30 40 50 60 70 80 90 100 f (kHz)

1860/61 G15

Spurious Free Dynamic Range vs fIN

100

90

80

70

60

50

40

30

20 10 0

1

TA = 25?C VCC = 5V VIN = 0dB

10

100

fIN (kHz)

1000

1860/61 G18

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