LINEAR TECHNOLOGY LTC2356-12, LTC2356-14 Technical data

FEATURES

FREQUENCY (MHz)

0.1

–80

THD, 2nd, 3rd (dB)

–74

–68

–62

–56

1 10 100

2356 G02

–86

–92

–98

–104

–50

THD
2nd

3rd

LTC2356-12/LTC2356-14

Serial 12-Bit/14-Bit, 3.5Msps

Sampling ADCs with Shutdown

U

DESCRIPTIO

■

3.5Msps Conversion Rate

■

74.1dB SINAD at 14-Bits, 71.1dB SINAD at 12-Bits

■

Low Power Dissipation: 18mW

■

3.3V Single Supply Operation

■

2.5V Internal Bandgap Reference can be Overdriven

■

3-Wire SPI-Compatible Serial Interface

■

Sleep (13µW) Shutdown Mode

■

Nap (4mW) Shutdown Mode

■

80dB Common Mode Rejection

■

±1.25V Bipolar Input Range

■

Tiny 10-Lead MSOP Package

U

APPLICATIO S

■

Communications

■

Data Acquisition Systems

■

Uninterrupted Power Supplies

■

Multiphase Motor Control

■

Multiplexed Data Acquisition

■

RFID

The LTC®2356-12/LTC2356-14 are 12-bit/14-bit, 3.5Msps
serial ADCs with differential inputs. The devices draw
only 5.5mA from a single 3.3V supply and come in a tiny
10-lead MSOP package. A Sleep shutdown feature further
reduces power consumption to 13µW. The combination of
speed, low power and tiny package makes the LTC2356-12/
LTC2356-14 suitable for high speed, portable applications.

The 80dB common mode rejection allows users to elimi­nate ground loops and common mode noise by measuring
signals differentially from the source.

The devices convert –1.25V to 1.25V bipolar inputs differ­entially. The absolute voltage swing for A

–

A

extends from ground to the supply voltage.

IN

IN

+

and

The serial interface sends out the conversion results during
the 16 clock cycles following a CONV rising edge for
compatibility with standard serial interfaces. If two addi­tional clock cycles for acquisition time are allowed after the
data stream in between conversions, the full sampling rate
of 3.5Msps can be achieved with a 63MHz clock.

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

All other trademarks are the property of their respective owners.

BLOCK DIAGRA

10µF

LTC2356-14

+

A

IN

–

A

IN

+

1

S & H

2

–

V

REF

3

GND

4

5 6 11

2.5V

REFERENCE

W

14-BIT ADC

EXPOSED PAD

3.3V10µF

THD, 2nd and 3rd vs Input Frequency

for Differential Input Signals

7

V

DD

THREE-

14-BIT LATCH

14

STATE

SERIAL

OUTPUT

PORT

TIMING

LOGIC

SDO

8

CONV

10

SCK

9

2356 BD

2356f

1

LTC2356-12/LTC2356-14

1
2
3
4
5

A

IN

+

A

IN

–

V

REF

GND
GND

10
9
8
7
6

CONV
SCK
SDO
V

DD

GND

TOP VIEW

11

MSE PACKAGE

10-LEAD PLASTIC MSOP

WWWU

ABSOLUTE AXI U RATI GS

(Notes 1, 2)

Supply Voltage (VDD) ................................................. 4V

Analog and V

(Note 3) ....................................– 0.3V to (V

Digital Input Voltages ................. – 0.3V to (V

Digital Output Voltage .................. – 0.3V to (V

Power Dissipation.............................................. 100mW

Operation Temperature Range

LTC2356C-12/LTC2356C-14 ................... 0°C to 70°C

LTC2356I-12/LTC2356I-14 ................ – 40°C to 85°C

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

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

Input Voltages

REF

+ 0.3V)

DD

+ 0.3V)

DD

+ 0.3V)

DD

UU

W

PACKAGE/ORDER I FOR ATIO

ORDER PART

NUMBER

LTC2356CMSE-12
LTC2356IMSE-12
LTC2356CMSE-14
LTC2356IMSE-14

MSE PART MARKING

T

= 125°C, θJA = 150°C/ W

JMAX

EXPOSED PAD (PIN 11) IS GND

MUST BE SOLDERED TO PCB

Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/

Consult factory for parts specified with wider operating temperature ranges.

LTCWN
LTCWN
LTCVF
LTCVF

CO VERTER CHARACTERISTICS

temperature range, otherwise specifications are at T

PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS

Resolution (No Missing Codes)

Integral Linearity Error (Notes 4, 5, 18)

Offset Error (Notes 4, 18)

Gain Error (Note 4, 18)

Gain Tempco Internal Reference (Note 4) ±15 ±15 ppm/°C

A ALOG I PUT

otherwise specifications are at T

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

V

I

C

t

t

t

CMRR Analog Input Common Mode Rejection Ratio fIN = 1MHz, VIN = 0V to 3V –60 dB

2

U

UU

IN

CM

IN

IN

ACQ

AP

JITTER

Analog Differential Input Range (Notes 3, 8, 9) 3.1V ≤ VDD ≤ 3.6V

Analog Common Mode + Differential 0 to V
Input Range (Note 10)

Analog Input Leakage Current

Analog Input Capacitance (Note 19) 13 pF

Sample-and-Hold Acquisition Time (Note 6)

Sample-and-Hold Aperture Delay Time 1 ns

Sample-and-Hold Aperture Delay Time Jitter 0.3 ps

The ● denotes the specifications which apply over the full operating

= 25°C. With internal reference. VDD = 3.3V

A

LTC2356-12 LTC2356-14

●

12 14 Bits

●

–2 ±0.25 2 –4 ±0.5 4 LSB

●

–10 ±1 10 –30 ±230 LSB

●

–40 ±5 40 –80 ±10 80 LSB

External Reference ±1 ±1 ppm/°C

The ● denotes the specifications which apply over the full operating temperature range,

= 25°C. With internal reference. VDD = 3.3V

A

●

●

●

f

= 100MHz, VIN = 0V to 3V –15 dB

IN

–1.25 to 1.25 V

DD

1 µA

39 ns

V

2356f

LTC2356-12/LTC2356-14

U

W

DY A IC ACCURACY

otherwise specifications are at T
DC. Differential signal drive with V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS

SINAD Signal-to-Noise Plus 100kHz Input Signal (Note 19) 71.1 74.1 dB

Distortion Ratio 1.4MHz Input Signal (Note 19)

THD Total Harmonic 100kHz First 5 Harmonics (Note 19) –86 –86 dB

Distortion 1.4MHz First 5 Harmonics (Note 19)

SFDR Spurious Free 100kHz Input Signal (Note 19) 86 86 dB

Dynamic Range 1.4MHz Input Signal (Note 19) 82 82 dB

IMD Intermodulation 0.625V

Distortion 1.56MHz into A

Code-to-Code V
Transition Noise

Full Power Bandwidth VIN = 2.5V
Full Linear Bandwidth S/(N + D) ≥ 68dB 5 5 MHz

= 25°C with external reference = 2.55V. VDD = 3.3V. Single-ended A

A

REF

The ● denotes the specifications which apply over the full operating temperature range,

= 1.5V at A

CM

1.4MHz Summed with 0.625V

P-P

= 2.5V (Note 18) 0.25 1 LSB

P-P

+

and A

IN

+

and Inverted into A

IN

, SDO = 11585LSB

–

IN

LTC2356-12 LTC2356-14

●

68 71.1 70 72.3 dB

●

P-P

–

IN

(Note 15) 50 50 MHz

P-P

–82 –76 –82 –78 dB

–82 –82 dB

+

signal drive with A

IN

–

IN

= 1.5V

RMS

UU U

I TER AL REFERE CE CHARACTERISTICS

full operating temperature range, otherwise specifications are at T

= 25°C. VDD = 3.3V

A

The ● denotes the specifications which apply over the

PARAMETER CONDITIONS MIN TYP MAX UNITS

V

Output Voltage I

REF

V

Output Tempco 15 ppm/°C

REF

V

Line Regulation VDD = 3.1V to 3.6V, V

REF

V

Output Resistance Load Current = 0.5mA 0.2 Ω

REF

V

Settling Time C

REF

External V

Input Range 2.55 V

REF

= 0 2.5 V

OUT

= 2.5V 600 µV/V

REF

= 10µF2ms

REF

DD

UU

DIGITAL I PUTS A D DIGITAL OUTPUTS

full operating temperature range, otherwise specifications are at T

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 VDD = 3.6V

Low Level Input Voltage VDD = 3.1V

Digital Input Current VIN = 0V to V

Digital Input Capacitance 5pF

High Level Output Voltage VDD = 3.3V, I

Low Level Output Voltage VDD = 3.1V, I

= 3.1V, I

V

DD

Hi-Z Output Leakage D

Hi-Z Output Capacitance D

Output Short-Circuit Source Current V

Output Short-Circuit Sink Current V

OUT

OUT

V

OUT

OUT

OUT

= 25°C. VDD = 3.3V

A

DD

OUT

OUT
OUT

= 0V to V

= 0V, VDD = 3.3V 20 mA

= VDD = 3.3V 15 mA

DD

The ● denotes the specifications which apply over the

●

2.4 V

●

●

= – 200µA

= 160µA 0.05 V
= 1.6mA

●

2.5 2.9 V

●

●

0.10 0.4 V

1pF

0.6 V

± 10 µA

± 10 µA

V

2356f

3

LTC2356-12/LTC2356-14

WU

POWER REQUIRE E TS

range, otherwise specifications are at T

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

DD

I

DD

P

D

Supply Voltage 3.1 3.3 3.6 V
Supply Current Active Mode

Power Dissipation Active Mode with SCK in Fixed State (Hi or Lo) 18 mW

= 25°C. (Note 17)

A

The ● denotes the specifications which apply over the full operating temperature

●

Nap Mode

●

Sleep Mode (LTC2356-12) 4 15 µA
Sleep Mode (LTC2356-14) 4 12 µA

5.5 8 mA

1.1 1.5 mA

WU

TI I G CHARACTERISTICS

range, otherwise specifications are at T

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

f

SAMPLE(MAX)

t

THROUGHPUT

t

SCK

t

CONV

t

1

t

2

t

3

t

4

t

5

t

6

t

7

t

8

t

9

t

10

t

12

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: When these pins are taken below GND or above V

clamped by internal diodes. This product can handle input currents greater
than 100mA below GND or greater than V

Note 4: Offset and full-gain specifications are measured for a single-ended

+

A

input with A

IN

Note 5: Integral linearity is tested with an external 2.55V reference and is
defined as the deviation of a code from the straight line passing through
the actual endpoints of a transfer curve. The deviation is measured from
the center of quantization band.

Note 6: Guaranteed by design, not subject to test.
Note 7: Recommended operating conditions.
Note 8: The analog input range is defined for the voltage difference

between A
driving A

Note 9: The absolute voltage at A
Note 10: If less than 3ns is allowed, the output data will appear one clock

cycle later. It is best for CONV to rise half a clock before SCK, when
running the clock at rated speed.

Maximum Sampling Rate per Channel
(Conversion Rate)

Minimum Sampling Period (Conversion + Acquisiton Period)
Clock Period (Note 16)
Conversion Time (Note 6) 16 18 SCLK cycles
Minimum High or Low SCLK Pulse Width (Note 6) 2 ns
CONV to SCK Setup Time (Notes 6, 10) 3 ns
Nearest SCK Edge Before CONV (Note 6) 0 ns
Minimum High or Low CONV Pulse Width (Note 6) 4 ns
SCK↑ to Sample Mode (Note 6) 4 ns
CONV↑ to Hold Mode (Notes 6, 11) 1.2 ns
16th SCK↑ to CONV≠ Interval (Affects Acquisition Period) (Notes 6, 7, 13) 45 ns
Delay from SCK to Valid Data (Notes 6, 12) 8 ns
SCK↑ to Hi-Z at SDO (Notes 6, 12) 6 ns
Previous SDO Bit Remains Valid After SCK (Notes 6, 12) 2 ns
V

Settling Time After Sleep-to-Wake Transition (Note 14) 2 ms

REF

–

grounded and using the internal 2.5V reference.

IN

+

IN

+

.

IN

and A

–

. Performance is specified with A

IN

+

and A

IN

= 25°C. VDD = 3.3V

A

without latchup.

DD

–

must be within this range.

IN

The ● denotes the specifications which apply over the full operating temperature

●

3.5 MHz

, they will be

DD

–

= 1.5V DC while

IN

●

●

15.872 10000 ns

Note 11: Not the same as aperture delay. Aperture delay is smaller (1ns)
because the 2.2ns delay through the sample-and-hold is subtracted from
the CONV to Hold mode delay.

Note 12: The rising edge of SCK is guaranteed to catch the data coming
out into a storage latch.

Note 13: The time period for acquiring the input signal is started by the
16th rising clock and it is ended by the rising edge of convert.

Note 14: The internal reference settles in 2ms after it wakes up from Sleep
mode with one or more cycles at SCK and a 10µF capacitive load.

Note 15: The full power bandwidth is the frequency where the output code
swing drops to 3dB with a 2.5V

input sine wave.

P-P

Note 16: Maximum clock period guarantees analog performance during
conversion. Output data can be read with an arbitrarily long clock.

Note 17: V

= 3.3V, f

DD

SAMPLE

= 3.5Msps.

Note 18: The LTC2356-14 is measured and specified with 14-bit resolution
(1LSB = 152µV) and the LTC2356-12 is measured and specified with
12-bit resolution (1LSB = 610µV).

Note 19: The sampling capacitor at each input accounts for 4.1pF of the
input capacitance.

286 ns

2356f

4

UW

TYPICAL PERFOR A CE CHARACTERISTICS

LTC2356-12/LTC2356-14

= 25°C, VDD = 3.3V (LTC2356-14).

T

A

SINAD vs Input Frequency

77

74

71

68

65

62

SINAD (dB)

59

56

53

50

0.1

1 10 100

FREQUENCY (MHz)

SFDR vs Input Frequency

92

86

80

74

68

SFDR (dB)

62

56

50

0.1

1 10 100

FREQUENCY (MHz)

2356 G01

2356 G03

THD, 2nd and 3rd vs Input Frequency

–50

–56

–62

–68

–74

–80

–86

THD, 2nd, 3rd (dB)

–92

–98

–104

0.1

THD
2nd

3rd

1 10 100

FREQUENCY (MHz)

SNR vs Input Frequency

77

74

71

68

65

62

SNR (dB)

59

56

53

50

0.1

1 10 100

FREQUENCY (MHz)

2356 G02

2356 G04

100kHz Sine Wave 8192 Point
FFT Plot

0

–10

–20
–30

–40

–50

–60

–70

MAGNITUDE (dB)

–80

–90

–100
–110
–120

250K

500K

0

1M

750K

FREQUENCY (Hz)

1.25M

1.5M

1.75M

2356 G05

1.4MHz Sine Wave 8192 Point
FFT Plot

0

–10

–20
–30

–40

–50

–60
–70

MAGNITUDE (dB)

–80

–90

–100
–110
–120

250K

500K

0

1M

750K

FREQUENCY (Hz)

1.25M

1.5M

1.75M

2356 G06

2356f

5