Linear Technology LTC2402, LTC2401 Datasheet

1-/2-Channel 24-Bit µPower

Final Electrical Specifications

No Latency ∆Σ

LTC2401/LTC2402

TM

ADC in MSOP-10

FEATURES

■

24-Bit ADC in Tiny MSOP-10 Package

■

1- or 2-Channel Inputs

■

Automatic Channel Selection (Ping-Pong) (LTC2402)

■

Zero Scale and Full Scale Set for Reference
and Ground Sensing

■

4ppm INL, No Missing Codes

■

4ppm Full-Scale Error

■

0.5ppm Offset

■

0.6ppm Noise

■

Internal Oscillator—No External Components Required

■

110dB Min, 50Hz/60Hz Notch Filter

■

Single Conversion Settling Time for
Multiplexed Applications

■

Reference Input Voltage: 0.1V to V

■

Live Zero—Extended Input Range Accommodates

CC

12.5% Overrange and Underrange

■

Single Supply 2.7V to 5.5V Operation

■

Low Supply Current (200µA) and Auto Shutdown

U

APPLICATIO S

■

Weight Scales

■

Direct Temperature Measurement

■

Gas Analyzers

■

Strain-Gage Transducers

■

Instrumentation

■

Data Acquisition

■

Industrial Process Control

U

January 2000

DESCRIPTIO

The LTC®2401/LTC2402 are 1- and 2-channel 2.7V to

5.5V micropower 24-bit analog-to-digital converters with
an integrated oscillator, 4ppm INL and 0.6ppm RMS
noise. These ultrasmall devices use delta-sigma technol­ogy and a new digital filter architecture that settles in a
single cycle. This eliminates the latency found in conven­tional ∆Σ converters and simplifies multiplexed applica­tions.

Through a single pin, the LTC2401/LTC2402 can be
configured for better than 110dB rejection at 50Hz or
60Hz ±2%, or can be driven by an external oscillator for
a user defined rejection frequency in the range 1Hz to
120Hz. The internal oscillator requires no external fre­quency setting components.

These converters accept an external reference voltage
from 0.1V to VCC. With an extended input conversion
range of –12.5% V
ZS

), the LTC2401/LTC2402 smoothly resolve the off-

SET

set and overrange problems of preceding sensors or
signal conditioning circuits.

The LTC2401/LTC2402 communicate through a 2- or
3-wire digital interface that 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.

to 112.5% V

REF

REF

(V

REF

= FS

SET

–

TYPICAL APPLICATIO

2.7V TO 5.5V

1µF

REFERENCE VOLTAGE

ZS

+ 0.1V TO V

SET

INPUT RANGE

TO 1.12V

–0.12V

REF

(V

= FS

REF

SET

0V TO FS

ANALOG

– ZS

SET

REF

SET

– 100mV

CC

)

U

V

CC

110

V

2

FS

3

CH1 SDO

4

CH0

5

ZS

F

CC

O

LTC2402

SET

SET

9

SCK

8

7

CS

6

GND

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen­tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

= INTERNAL OSC/50Hz REJECTION
= EXTERNAL CLOCK SOURCE
= INTERNAL OSC/60Hz REJECTION

3-WIRE
SPI INTERFACE

24012 TA01

Pseudo Differential Bridge Digitizer

2.7V TO 5.5V

1

V

CC

LTC2402

2

FS

SET

4

CH0

3

CH1

5

ZS

SET

GND

9

SCK

8

CS

F

O

7

10

3-WIRE
SPI INTERFACE

INTERNAL OSCILLATOR
60Hz REJECTION

SDO

6

24012TA02

1

LTC2401/LTC2402

1
2
3
4
5

V

CC

FS

SET

CH1
CH0

ZS

SET

10
9
8
7
6

F

O

SCK
SDO
CS
GND

TOP VIEW

MS10 PACKAGE

10-LEAD PLASTIC MSOP

WW

W

ABSOLUTE MAXIMUM RATINGS

U

(Notes 1, 2)

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)

UUW

PACKAGE/ORDER INFORMATION

TOP VIEW

10

1

V

CC

FS

2

SET

V

3

IN

NC

4

ZS

5

SET

MS10 PACKAGE

10-LEAD PLASTIC MSOP

T

= 125°C, θJA = 130°C/W

JMAX

F

O

SCK

9

SDO

8

CS

7

GND

6

Consult factory for Military grade parts.

ORDER PART NUMBER

LTC2401CMS
LTC2401IMS

MS10 PART MARKING

LTMB
LTMC

Operating Temperature Range

LTC2401/LTC2402C ................................ 0°C to 70°C

LTC2401/LTC2402I ............................ –40°C to 85°C

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

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

ORDER PART NUMBER

LTC2402CMS
LTC2402IMS

MS10 PART MARKING

T

= 125°C, θJA = 130°C/W

JMAX

LTMD

LTME

U

CONVERTER CHARACTERISTICS

temperature range, otherwise specifications are at TA = 25°C. V

PARAMETER CONDITIONS MIN TYP MAX UNITS

Resolution ● 24 Bits
No Missing Codes Resolution 0.1V ≤ FS
Integral Nonlinearity FS

FS

SET
SET

Offset Error 2.5V ≤ FS
Offset Error Drift 2.5V ≤ FS
Full-Scale Error 2.5V ≤ FS
Full-Scale Error Drift 2.5V ≤ FS
Total Unadjusted Error FS

FS

SET
SET

Output Noise VIN = 0V (Note 13) 3 µV
Normal Mode Rejection 60Hz ±2% (Note 7) ● 110 130 dB
Normal Mode Rejection 50Hz ±2% (Note 8) ● 110 130 dB
Power Supply Rejection, DC FS
Power Supply Rejection, 60Hz ±2% FS
Power Supply Rejection, 50Hz ±2% FS

SET

SET

SET

≤ VCC, ZS

SET

= 2.5V, ZS
= 5V, ZS

≤ VCC, ZS

SET

≤ VCC, ZS

SET

≤ VCC, ZS

SET

≤ VCC, ZS

SET

SET

= 2.5V, ZS
= 5V, ZS

SET

= 2.5V, ZS
= 2.5V, ZS
= 2.5V, ZS

SET

= 0V (Note 6) ● 4 15 ppm of V

SET

= 0V 10 ppm of V

SET

SET

SET

The ● denotes specifications which apply over the full operating

= FS

REF

= 0V (Note 5) ● 24 Bits

SET

= 0V (Note 6) ● 2 10 ppm of V

= 0V ● 0.5 2 ppm of V

SET

= 0V 0.01 ppm of V

SET

= 0V ● 4 10 ppm of V

SET

= 0V 0.04 ppm of V

SET

= 0V 5 ppm of V

= 0V, VIN = 0V 100 dB
= 0V, VIN = 0V, (Note 7) 110 dB
= 0V, VIN = 0V, (Note 8) 110 dB

SET

– ZS

. (Notes 3, 4)

SET

REF

REF

REF
REF

REF

/°C

REF

/°C

REF
REF

RMS

2

LTC2401/LTC2402

UU

U

A ALOG I PUT A D REFERE CE

temperature range, otherwise specifications are at TA = 25°C. V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

IN

FS

SET

ZS

SET

C

S(IN)

C

S(REF)

I

IN(LEAK)

I

REF(LEAK)

Input Voltage Range (Note 14) ● –0.125 • V
Full-Scale Set Range ● 0.1 + ZS
Zero-Scale Set Range ● 0FS
Input Sampling Capacitance 10 pF
Reference Sampling Capacitance 15 pF
Input Leakage Current CS = V
Reference Leakage Current V

U

CC

= 2.5V, CS = V

REF

The ● denotes specifications which apply over the full operating

REF

= FS

CC

SET

– ZS

. (Note 3)

SET

REF

SET

● –10 1 10 nA

● –12 1 12 nA

1.125 • V
V

CC

– 0.1 V

SET

REF

V
V

UU

DIGITAL I PUTS A D DIGITAL OUTPUTS

operating temperature range, otherwise specifications are at TA = 25°C. (Note 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

IH

V

IL

V

IH

V

IL

I

IN

I

IN

C

IN

C

IN

V

OH

V

OL

V

OH

V

OL

I

OZ

High Level Input Voltage 2.7V ≤ VCC ≤ 5.5V ● 2.5 V
CS, F

O

Low Level Input Voltage 4.5V ≤ VCC ≤ 5.5V ● 0.8 V
CS, F

O

High Level Input Voltage 2.7V ≤ VCC ≤ 5.5V (Note 9) ● 2.5 V
SCK 2.7V ≤ V

Low Level Input Voltage 4.5V ≤ VCC ≤ 5.5V (Note 9) ● 0.8 V
SCK 2.7V ≤ V

Digital Input Current 0V ≤ VIN ≤ V
CS, F

O

Digital Input Current 0V ≤ VIN ≤ VCC (Note 9) ● –10 10 µA
SCK

Digital Input Capacitance 10 pF
CS, F

O

Digital Input Capacitance (Note 9) 10 pF
SCK

High Level Output Voltage IO = –800µA ● VCC – 0.5 V
SDO

Low Level Output Voltage IO = 1.6mA ● 0.4 V
SDO

High Level Output Voltage IO = –800µA (Note 10) ● VCC – 0.5 V
SCK

Low Level Output Voltage IO = 1.6mA (Note 10) ● 0.4 V
SCK

High-Z Output Leakage ● –10 10 µA
SDO

2.7V ≤ VCC ≤ 3.3V 2.0 V

2.7V ≤ VCC ≤ 5.5V 0.6 V

The ● denotes specifications which apply over the full

≤ 3.3V (Note 9) 2.0 V

CC

≤ 5.5V (Note 9) 0.6 V

CC

CC

● –10 10 µA

WU

POWER REQUIRE E TS

The ● denotes specifications which apply over the full operating temperature range,
otherwise specifications are at TA = 25°C. (Note 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

CC

I

CC

Supply Voltage ● 2.7 5.5 V
Supply Current

Conversion Mode CS = 0V (Note 12)
Sleep Mode CS = V

(Note 12) ● 20 30 µA

CC

● 200 300 µA

3

LTC2401/LTC2402

UW

TI I G CHARACTERISTICS

range, otherwise specifications are at TA = 25°C. (Note 3)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

f

EOSC

t

HEO

t

LEO

t

CONV

f

ISCK

D

ISCK

f

ESCK

t

LESCK

t

HESCK

t

DOUT_ISCK

t

DOUT_ESCK

t

1

t2 CS ↑ to SDO High Z ● 0 150 ns
t3 CS ↓ to SCK ↓ (Note 10) ● 0 150 ns
t4 CS ↓ to SCK ↑ (Note 9) ● 50 ns
t

KQMAX

t

KQMIN

t

5

t

6

External Oscillator Frequency Range ● 2.56 307.2 kHz
External Oscillator High Period ● 0.5 390 µs
External Oscillator Low Period ● 0.5 390 µs
Conversion Time FO = 0V ● 130.66 133.33 136 ms

Internal SCK Frequency Internal Oscillator (Note 10) 19.2 kHz

Internal SCK Duty Cycle (Note 10) 45 55 %
External SCK Frequency Range (Note 9) ● 2000 kHz
External SCK Low Period (Note 9) ● 250 ns
External SCK High Period (Note 9) ● 250 ns
Internal SCK 32-Bit Data Output Time Internal Oscillator (Notes 10, 12) ● 1.64 1.67 1.70 ms

External SCK 32-Bit Data Output Time (Note 9) ● 32/f
CS ↓ to SDO Low Z ● 0 150 ns

SCK ↓ to SDO Valid ● 200 ns
SDO Hold After SCK ↓ (Note 5) ● 15 ns
SCK Set-Up Before CS ↓ ● 50 ns
SCK Hold After CS ↓ ● 50 ns

The ● denotes specifications which apply over the full operating temperature

= V

F

O

CC

External Oscillator (Note 11)

External Oscillator (Notes 10, 11) f

External Oscillator (Notes 10, 11)

● 156.80 160 163.20 ms

● 20480/f

● 256/f

(in kHz) ms

EOSC

/8 kHz

EOSC

(in kHz) ms

EOSC

(in kHz) ms

ESCK

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

Note 2: All voltage values are with respect to GND.
Note 3: V

= 2.7 to 5.5V unless otherwise specified. Input source

CC

resistance = 0Ω.
Note 4: Internal Conversion Clock source with the F

to GND or to V
f

= 153600Hz unless otherwise specified.

EOSC

or to external conversion clock source with

CC

pin tied

O

Note 5: Guaranteed by design, not subject to test.
Note 6: 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 7: FO = 0V (internal oscillator) or f

= 153600Hz ±2%

EOSC

(external oscillator).
Note 8: F

= VCC (internal oscillator) or f

O

= 128000Hz ±2%

EOSC

(external oscillator).

Note 9: The converter is in external SCK mode of operation such that
the SCK pin is used as digital input. The frequency of the clock signal
driving SCK during the data output is f

and is expressed in kHz.

ESCK

Note 10: The converter is in internal SCK mode of operation such that
the SCK pin is used as digital output. In this mode of operation, the
SCK pin has a total equivalent load capacitance C

LOAD

= 20pF.

Note 11: The external oscillator is connected to the FO pin. The external
oscillator frequency, f

, is expressed in kHz.

EOSC

Note 12: The converter uses the internal oscillator.

= 0V or FO = VCC.

F

O

Note 13: The output noise includes the contribution of the internal
calibration operations.

Note 14: For reference voltage values V
of –0.125 • V

to 1.125 • V

REF

is limited by the absolute maximum

REF

rating of the Analog Input Voltage pin (Pin 3). For 2.5V < V

0.267V + 0.89 • V
For 0.267V + 0.89 • V
to V

+ 0.3V.

CC

, the input voltage range is –0.3V to 1.125 • V

CC

< V

CC

≤ VCC, the input voltage range is –0.3V

REF

> 2.5V, the extended input

REF

REF

≤

.

REF

4