Linear Technology LTC1401 Datasheet

FEATURES

LTC1401

Complete

SO-8, 12-Bit, 200ksps

ADC with Shutdown

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DESCRIPTION

■

Complete 12-Bit ADC with Reference in SO-8

■

Single Supply 3V Operation

■

Sample Rate: 200ksps

■

Power Dissipation: 15mW (Typ)

■

68dB S/(N + D) and – 72dB THD at 50kHz

■

No Missing Codes Over Temperature

■

Nap Mode with Instant Wake-Up: 1.5mW

■

Sleep Mode: 19.5µW

■

Shutdown Mode: 13.5µW

■

High Impedance Analog Input

■

Input Range (0.5mV/LSB): 0V to 2.048V

■

Internal Reference Can Be Overdriven Externally

■

3-Wire Interface to DSPs and Processors (SPI and
MICROWIRETM Compatible)

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APPLICATIONS

■

Low Power and Battery-Operated Systems

■

Handheld or Portable Instruments

■

High Speed Data Acquisition

■

Digital Signal Processing

■

Multiplexed Data Acquisition Systems

■

Telecommunication

■

Digital Radio

■

Spectrum Analysis

The LTC®1401 is a complete 200ksps, 12-bit A/D con­verter that converts 0V to 2.048V unipolar input and draws
only 15mW from a single 3V supply. This easy-to-use
device comes complete with a 315ns sample-and-hold
and a precision reference. Maximum DC specifications
include ±1LSB INL, ±1LSB DNL and 45ppm/°C full-scale
drift over temperature.

The LTC1401 has three power saving modes: Nap and
Sleep, through the serial interface and Shutdown by
setting the SHDN pin to zero. In Nap mode, it consumes
only 1.5mW of power and can wake up and convert
immediately. In Sleep (Shutdown) mode, it consumes

19.5µW (13.5µW) of power typically. Upon power-up
from Sleep or Shutdown mode, a reference ready (REFRDY)
signal is available in the serial word to indicate that the
reference has settled and the chip is ready to convert.

The 3-wire serial port allows compact and efficient data
transfer to a wide range of microprocessors, microcon­trollers and DSPs.

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

MICROWIRE is a trademark of National Semiconductor Corporation.

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TYPICAL APPLICATION

Single 3V Supply, 200kHz, 12-Bit Sampling A/D Converter

3V

+

ANALOG INPUT

(0V TO 2.048V)

1.20V

1

V

CC

0.1µF10µF

LTC1401

2

A

IN

3

V

+

0.1µF10µF

REF

4

GND

SHDN

CONV

CLK

D

OUT

8

7

6

5

SERIAL

DATA LINK

MPU

P1.4

P1.3

P1.2

1401 TA01

Power Consumption vs Sample Rate

100

3.2MHz CLOCK

= 25°C

T

A

10

1

0.1

SUPPLY CURRENT (mA)

0.01

0.001

0.01

NORMAL CONVERSION

NAP MODE 
BETWEEN CONVERSION

SHUTDOWN MODE 
BETWEEN CONVERSION

SLEEP MODE BETWEEN
CONVERSION

100

0.1 1

10 1k 1M

SAMPLE RATE (Hz)

10k 100k

LTC1401 • TA02

1

LTC1401

TOP VIEW

V

CC



A

IN



V

REF



GND

SHDN
CONV
CLK
D

OUT

S8 PACKAGE

8-LEAD PLASTIC SO

1

2

3

4

8

7

6

5

WW

W

ABSOLUTE MAXIMUM RATINGS

(Notes 1, 2)

Supply Voltage (VCC) ................................................. 7V

Analog Input Voltage (Note 3) ..... –0.3V to (VCC + 0.3V)

Digital Input Voltage (Note 4) ....................–0.3V to 12V

Digital Output Voltage.................. –0.3V to (VCC + 0.3V)

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PACKAGE/ORDER INFORMATION

ORDER PART

NUMBER

LTC1401CS8
LTC1401IS8

Power Dissipation.............................................. 300mW

Operating Ambient Temperature Range

LTC1401C................................................0°C to 70°C

LTC1401I............................................ – 40°C to 85°C

T

= 125°C, θJA = 130°C/ W

JMAX

S8 PART MARKING

1401
1401I

Operating Junction Temperature ......................... 125°C

Storage Temperature Range ................. –65°C to 150°C

Consult factory for PDIP packages and Military grade parts.

Lead Temperature (Soldering, 10 sec)..................300°C

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POWER REQUIRE E TS

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

CC

I

CC

P

D

Supply Voltage 2.7 3.0 3.6 V
Supply Current f

Power Dissipation f

(Note 5)

= 200ksps ● 510 mA

SAMPLE

Nap Mode
Sleep Mode
Shutdown Mode ● 4.5 10 µA

= 200ksps ● 15 30 mW

SAMPLE

Nap Mode
Sleep Mode
Shutdown Mode ● 13.5 30 µW

● 0.5 1.0 mA

● 6.5 15 µA

● 1.5 3.0 mW

● 19.5 45 µW

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IA

U
PUT

(Note 5)

During Conversions (Hold Mode) 5 pF

(Note 5)

= 0 1.180 1.200 1.220 V

OUT

= 0 ● ±10 ±45 ppm/°C

OUT

 ≤ 1mA 2 LSB/mA

OUT

= 10µF3ms

VREF

U

IN

U

LOG

IN

IN

Analog Input Range ● 0 to 2.048 V
Analog Input Leakage Current During Conversions (Hold Mode) ● ±1 µA
Analog Input Capacitance Between Conversions (Sample Mode) 45 pF

UU

A

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V
I
C

I TER AL REFERE CE CHARACTERISTICS

PARAMETER CONDITIONS MIN TYP MAX UNITS

V

Output Voltage I

REF

V

Output Tempco I

REF

V

Line Regulation 2.7V ≤ VCC ≤ 3.6V 0.01 LSB/V

REF

V

Load Regulation 0 ≤ I

REF

V

Wake-Up Time from Sleep or Shutdown Mode C

REF

2

LTC1401

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CO

PARAMETER CONDITIONS MIN TYP MAX UNITS

Resolution (No Missing Codes) ● 12 Bits
Integral Linearity Error (Note 7) ● ±1 LSB
Differential Linearity Error ● ±1 LSB
Offset Error ±6 LSB

Full-Scale Error ±15 LSB
Full-Scale Tempco I

DY

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

S/(N + D) Signal-to-Noise 50kHz Input Signal ● 65 68 dB

THD Total Harmonic Distortion 50kHz Input Signal ● –72 –65 dB

IMD Intermodulation Distortion f

VERTER

W

U

IC

A

Plus Distortion Ratio 100kHz Input Signal 65 dB

Up to 5th Harmonic 100kHz Input Signal –66 dB
Peak Harmonic or 50kHz Input Signal ● –74 –65 dB

Spurious Noise 100kHz Input Signal –67 dB

Full Power Bandwidth 2 MHz
Full Linear Bandwidth (S/(N + D) ≥ 68dB) 50 kHz

CCHARA TERIST

ACCURACY

(Note 5)

ICS

OUT(REF)

IN1

With internal reference (Note 5)

● ±8 LSB

= 0 ● ±10 ±45 ppm/°C

= 49.853kHz, f

= 53.076kHz –69 dB

IN2

UU

DIGITAL I PUTS AND OUTPUTS

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

IH

V

IL

I

IN

C

IN

V

OH

V

OL

I

OZ

C

OZ

I

SOURCE

I

SINK

High Level Input Voltage V
Low Level Input Voltage VCC = 2.7V ● 0.8 V
Digital Input Current VIN = 0V to V
Digital Input Capacitance 5pF
High Level Output Voltage VCC = 2.7V, IO = –10µA ● 2.40 2.64 V

Low Level Output Voltage VCC = 2.7V, IO = 400µA ● 0.13 0.4 V
Hi-Z Output Leakage D
Hi-Z Output Capacitance D
Output Source Current V
Output Sink Current V

OUT

OUT

(Note 5)

= 3.6V ● 2.0 V

CC

CC

VCC = 2.7V, IO = –200µA ● 2.25 2.50 V

V

= 0V to V

OUT

= 0 –5 mA

OUT

= V

OUT

CC

CC

● ±10 µA

● ±10 µA

15 pF

10 mA

3

LTC1401

W

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TI I G CHARACTERISTICS

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

f

SAMPLE(MAX)

t

CONV

t

ACQ

f

CLK

t

CLK

t

WK(NAP)

t

1

t

2

t

3

t

4

t

5

t

6

t

7

t

8

t

9

t

10

Maximum Sampling Frequency ● 200 kHz
Conversion Time f
Acquisition Time 315 ns
CLK Frequency ● 0.1 3.2 MHz
CLK Pulse Width (Note 6) ● 60 ns
Time to Wake Up from Nap Mode 350 ns
CLK Pulse Width to Return to Active Mode ● 60 ns
CONV↑ to CLK↑ Setup Time ● 100 ns
CONV↑ After Leading CLK↑ ● 0ns
CONV Pulse Width (Note 8) ● 50 ns
Time from CLK↑ to Sample Mode 80 ns
Aperture Delay of Sample-and-Hold Jitter < 50ps 45 ns
Minimum Delay Between Conversion (Note 6) ● 350 550 ns
Delay Time, CLK↑ to D
Delay Time, CLK↑ to D
Time from Previous Data Remains Valid After CLK↑ C

Valid C

OUT

Hi-Z C

OUT

(Note 5)

= 3.2MHz ● 4.1 µs

CLK

= 20pF ● 60 120 ns

LOAD

= 20pF ● 60 120 ns

LOAD

= 20pF ● 15 50 ns

LOAD

The ● denotes specifications which apply over the full operating
temperature range; all other limits and typicals apply to TA = 25°C.

Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.

Note 2: All voltage values are with respect to GND.
Note 3: When these pin voltages are taken below GND or above V

will be clamped by internal diodes. This product can handle input currents
greater than 40mA without latch-up if the pin is driven below GND or
above VCC.

Note 4: When these pin voltages are taken below GND, they will be clamped
by internal diodes. This product can handle input currents greater than 40mA
without latch-up if the pin is driven below GND. These pins are not clamped

.

to V

CC

CC

, they

Note 5: V
specified.

Note 6: Guaranteed by design, not subject to test.
Note 7: Integral nonlinearity is defined as the 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 8: The rising edge of CONV starts a conversion. If CONV returns low
at a bit decision point during the conversion, it can create small errors. For
best performance, ensure that CONV returns low either within 120ns after
the conversion starts (i.e., before the first bit decision) or after the 14
clock cycles. (Figure 13 Timing Diagram).

= 3V, f

CC

= 200kHz, tr = tf = 5ns unless otherwise

SAMPLE

4

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INPUT FREQUENCY (kHz)

10

0

SIGNAL/(NOISE + DISTORTION)(dB)

10

20

30

40

80

100 1000

LTC1401 • TPC03

50

60

70

VIN = 0dB

VIN = –20dB

VIN = –60dB

TA = 25°C
f

SAMPLE

= 200kHz



SOURCE RESISTANCE (Ω)

10

2500

t

ACQ

(ns)

3000

3500

4000

4500

100 1k 10k

LTC1401 • TPC06

2000

1500

500

0

1000

TA = 25°C

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TYPICAL PERFORMANCE CHARACTERISTICS

LTC1401

Differential Nonlinearity vs
Output Code

1.0
f

= 200kHz

SAMPLE

0.5

0

DNL ERROR (LSBs)

–0.5

–1.0

0

512 1024 1536 2048

2560 3072 3584 4096

CODE

Signal-to-Noise Ratio (Without
Harmonics) vs Input Frequency

80

70

60

50

40

30

20

SIGNAL-TO-NOISE RATIO (dB)

10

TA = 25°C

= 200kHz

f

SAMPLE



0

10

INPUT FREQUENCY (kHz)

100 1000

LTC1401 • TPC01

LTC1401 • TPC04

Integral Nonlinearity vs
Output Code

1.0
f

= 200kHz

SAMPLE

0.5

0

INL ERROR (LSBs)

–0.5

–1.0

0

512 1024 1536 2048

2560 3072 3584 4096

CODE

Peak Harmonic or Spurious Noise
vs Input Frequency

0

TA = 25°C

–10

–20

–30

–40

–50

–60

–70

–80

SPURIOUS-FREE DYNAMIC RANGE (dB)

–90

10

= 200kHz

f

SAMPLE



INPUT FREQUENCY (kHz)

100 1000

S/(N + D) vs Input Frequency
and Amplitude

LTC1401 • TPC02

Acquisition Time vs
Source Impedance

LTC1401 • TPC05

Reference Voltage vs
Load Current

1.40
TA = 25°C

1.35

1.30

1.25

1.20

1.15

1.10

1.05

REFERENCE VOLTAGE (V)

1.00

0.95

0.90

–7

–6 –4

–5

–2 2

–3

LOAD CURRENT (mA)

–1

0

1

LTC1401 • TPC07

Power Supply Feedthrough vs
Ripple Frequency

0

f

= 200kHz

SAMPLE

–10

= 49.853kHz

f

IN

(V

V

–20

CC



–30
–40

–50
–60
–70
–80

POWER SUPPLY FEEDTHROUGH (dB)

–90

–100

1

= 1mV)

RIPPLE

10 100 1000

RIPPLE FREQUENCY (kHz)

LTC1401 • TPC08

Supply Current vs Temperature

12

10

8

6

4

SUPPLY CURRENT (mA)

2

0

–50

–25 0

TEMPERATURE (˚C)

f

SAMPLE

VIN = 3.6V

VIN = 3V

VIN = 2.7V

50 100 125

25 75

= 200kHz

LTC1401 • TPC09

5

LTC1401



PIN FUNCTIONS

UUU

V

(Pin 1): Positive Supply, 3V. Bypass to GND (10µF

CC

tantalum in parallel with 0.1µF ceramic).

AIN (Pin 2): Analog Input. 0V to 2.048V.
V

(Pin 3): 1.2V Reference Output. Bypass to GND

REF

(10µF tantalum in parallel with 0.1µF ceramic).
GND (Pin 4): Ground. GND should be tied directly to an

analog ground plane.

D

(Pin 5): The A/D conversion result is shifted out from

OUT

this pin.

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FUNCTIONAL BLOCK DIAGRA

A

IN

V

REF

1.20V REF

CLK (Pin 6): Clock. This clock synchronizes the serial data
transfer. A minimum CLK pulse of 60ns signals the ADC to
wake up from Nap or Sleep mode.

CONV (Pin 7): Conversion Start Signal. This active high
signal starts a conversion on its rising edge. Keeping CLK
low and pulsing CONV two/four times will put the ADC into
Nap/Sleep mode.

SHDN (Pin 8): Shutdown Input. Pull this pin Low to put the
ADC in Shutdown mode and save power (REFRDY will go
Low). The device will draw 4.5µA in this mode.

C

SAMPLE

ZEROING SWITCH

V

CC

GND
SHDN



TEST CIRCUITS

CLK

CONV

D

OUT

CONTROL

LOGIC

3k

Hi-Z TO V
V

OL TO VOH

V

TO Hi-Z

OH

12-BIT CAPACITIVE DAC COMP

12

SUCCESSIVE APPROXIMATION 

REGISTER/PARALLEL TO 

SERIAL CONVERTER

3V

3k

D

OUT

C

LOAD

OH

Hi-Z TO V
V

OH TO VOL

V

TO Hi-Z

OL

C

LOAD

OL

LTC1401 • TC01

D

OUT

LTC1401 • BD01

6