LINEAR TECHNOLOGY LTC1740 Technical data

FEATURES

LTC1740

14-Bit, 6Msps,

Sampling ADC

U

DESCRIPTIO

■

6Msps Sample Rate

■

79dB S/(N + D) and 91dB SFDR at 2.5MHz f

■

Single 5V Supply or ±5V Supplies

■

Integral Nonlinearity Error: <1LSB

■

Differential Nonlinearity: <0.5LSB

■

80MHz Full-Power Bandwidth Sampling

■

±2.5V and ±1.25V Bipolar Input Ranges

■

2.5V Signal Ground Available

■

Out-of-Range Indicator

■

True Differential Inputs with 75dB CMRR

■

Power Dissipation: 245mW

■

36-Pin SSOP Package (0.209 Inch Width)

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APPLICATIO S

■

Telecommunications

■

Multiplexed Data Acquisition Systems

■

High Speed Data Acquisition

■

Spectral Analysis

■

Imaging Systems

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

IN

The LTC®1740 is a 6Msps, 14-bit sampling A/D converter
that draws only 245mW from either a single 5V or dual
±5V supplies. This easy-to-use device includes a high
dynamic range sample-and-hold and a programmable
precision reference.

The LTC1740 has a flexible input circuit that allows differ­ential full-scale input ranges of ±2.5V and ±1.25V with the
internal reference, or any full-scale input range up to
±2.5V with an external reference. The input common
mode voltage is arbitrary, though a 2.5V reference is
provided for single supply applications.

DC specifications include 1LSB typical INL, 0.5LSB typical
DNL and no missing codes over temperature. Outstanding
AC performance includes 79dB S/(N␣ +␣ D) and 91dB SFDR
at an input frequency of 2.5MHz.

The unique differential input sample-and-hold can acquire
single-ended or differential input signals up to its 80MHz
bandwidth. The 75dB common mode rejection allows
users to eliminate ground loops and common mode noise
by measuring signals differentially from the source. A
separate output logic supply allows direct connection to
3V components.

BLOCK DIAGRA

5V

1µF

+

A

IN

1µF

1

2

3

4

5

–A

IN

V

CM

SENSE

V

REF

0V OR –5V

+

1000pF

V

IN

–

1µF

1µF

8

MODE SELECT

V

SS

30

29 6

W

5V 3V TO 5V

1µF

9

V

V

DD

DD

PIPELINED 14-BIT ADCS/H

DIGITAL CORRECTION

REFERENCE

2.250V

V

GND

SS

33

V

V

DD

DD

LOGIC

2.5V

GND7GND10GND34GND

31 11

BUFFERS

1932

OUTPUT

OV

OGND

1µF

DD

D13 (MSB)

D0 (LSB)

BUSY

CLK

OGND

28

4096-Point FFT

OF

36

12

D7

18

20

26

27

35

1740 TA01

DIGITAL
OUTPUT

6MHz CLK

D6

0

f

= 6MHz

SMPL

= 2.5MHz, 5V

f

IN

5V SUPPLY

–20

–40

–60

AMPLITUDE (dB)

–80

–100

–120

0

0.5

P-P

1.0 1.5 2.0
FREQUENCY (MHz)

2.5 3.0

1740 TA02

1740f

1

LTC1740

WW

W

U

ABSOLUTE MAXIMUM RATINGS

0VDD = VDD (Notes 1, 2)

Supply Voltage (VDD)................................................. 6V

Negative Supply Voltage (VSS) ................................ – 6V

Total Supply Voltage (VDD to VSS) ........................... 12V

Analog Input Voltage

(Note 3) .........................(VSS – 0.3V) to (VDD + 0.3V)

Digital Input Voltage

(Note 3) .........................(VSS – 0.3V) to (VDD + 0.3V)

Digital Output Voltage........(VSS – 0.3V) to (VDD + 0.3V)

Power Dissipation.............................................. 500mW

Operating Temperature Range

LTC1740C ............................................... 0°C to 70°C

LTC1740I............................................ –40°C to 85°C

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

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

W

PACKAGE/ORDER INFORMATION

+A
–A

V

SENSE

V

REF

GND
GND

V
V

GND

OGND

D13 (MSB)

D12
D11
D10

TOP VIEW

1

IN

2

IN

3

CM

4
5
6
7
8

DD

9

DD

10
11
12
13
14
15
16

D9

17

D8

18

D7

G PACKAGE

36-LEAD PLASTIC SSOP

T

= 125°C, θJA = 95°C/W

JMAX

OF

36

CLK

35

GND

34

V

33

DD

V

32

DD

GND

31

V

30

SS

V

29

SS

OGND

28

BUSY

27

D0

26

D1

25

D2

24

D3

23

D4

22

D5

21

D6

20

OV

19

DD

ORDER PART

NUMBER

LTC1740CG
LTC1740IG

UU

Consult LTC Marketing for parts specified with wider operating temperature
ranges.

U

CO VERTER CHARACTERISTICS

temperature range, otherwise specifications are at TA = 25°C. With internal 4.500V reference. Specifications are guaranteed for both
dual supply and single supply operation. (Notes 4, 5)

PARAMETER CONDITIONS MIN TYP MAX UNITS

Resolution (No Missing Codes) ● 14 Bits
Integral Linearity Error (Note 6) 1 ±2.5 LSB
Differential Linearity Error ● –1 0.5 1.25 LSB
Offset Error (Note 7) ±15 ±60 LSB

Full-Scale Error ±30 ±75 LSB
Full-Scale Tempco I

The ● denotes specifications which apply over the full operating

● ±80 LSB

= 0 ±15 ppm/°C

OUT(REF)

2

1740f

LTC1740

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A ALOG I PUT

specifications are at TA = 25°C. Specifications are guaranteed for both dual supply and single supply operation. (Note 4)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

IN

I

IN

C

IN

t

ACQ

t

AP

t

jitter

CMRR Analog Input Common Mode Rejection Ratio VSS < (–AIN = +AIN) < V

Analog Input Range V

Analog Input Leakage Current ● ±10 µA
Analog Input Capacitance Between Conversions 12 pF

Sample-and-Hold Acquisition Time 67 ns
Sample-and-Hold Aperture Delay Time –900 ps
Sample-and-Hold Aperture Delay Time Jitter 0.6 ps

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

= 4.5V (SENSE = 0V) ● ±2.50 V

REF

V

= 2.25V (SENSE Tied to V

REF

External V

During Conversions 4 pF

(SENSE = 5V) ● ±V

REF

DD

) ● ±1.25 V

REF

/1.8 V

REF

75 dB

RMS

UW

DY A IC ACCURACY

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

S/(N + D) Signal-to-Noise Plus Distortion Ratio 1MHz Input Signal 79.1 dB

THD Total Harmonic Distortion 1MHz Input Signal, First 5 Harmonics –90 dB

SFDR Spurious Free Dynamic Range 1MHz Input Signal 92 dB

Full-Power Bandwidth 80 MHz
Input Referred Noise 0.45 LSB

VDD = OVDD = 5V, VSS = 0V, V

2.5MHz Input Signal 79.0 dB

2.5MHz Input Signal, First 5 Harmonics –89 dB

2.5MHz Input Signal 91 dB

= 4.5V, AIN = –0.1dBFS, AC coupled differential input.

REF

RMS

UU U

I TER AL REFERE CE CHARACTERISTICS

TA = 25°C. Specifications are guaranteed for both dual supply and single supply operation. (Note 4)

PARAMETER CONDITIONS MIN TYP MAX UNITS

VCM Output Voltage I
VCM Output Tempco I
VCM Line Regulation 4.75V ≤ VDD ≤ 5.25V 0.6 mV/V

VCM Output Resistance 0.1mA ≤ I
V

Output Voltage SENSE = GND, I

REF

V

Output Tempco ±15 ppm/°C

REF

= 0 2.475 2.500 2.525 V

OUT

= 0 ±15 ppm/°C

OUT

–5.25V ≤ V

SENSE = V
SENSE = V

≤ –4.75V 0.03 mV/V

SS

 ≤ 0.1mA 8 Ω

OUT

= 0 4.500 V

OUT

, I

= 0 2.250 V

REF

OUT

DD

Drive V

External Reference

with V

REF

1740f

3

LTC1740

UU

DIGITAL I PUTS A D DIGITAL OUTPUTS

operating temperature range, otherwise specifications are at TA = 25°C. Specifications are guaranteed for both dual supply and single
supply operation. (Note 4)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

IH

V

IL

I

IN

C

IN

V

OH

V

OL

I

SOURCE

I

SINK

High Level Input Voltage V

Low Level Input Voltage VDD = 4.75V, VSS = 0V ● 0.8 V

Digital Input Current VIN = 0V to V
Digital Input Capacitance 1.8 pF
High Level Output Voltage 0VDD = 4.75V, IO = –10µA 4.74 V

Low Level Output Voltage 0VDD = 4.75V, IO = 160µA 0.05 V

Output Source Current V
Output Sink Current V

= 5.25V, VSS = 0V ● 2.4 V

DD

= 5.25V, VSS = –5V ● 2.4 V

V

DD

= 4.75V, VSS = –5V ● 0.8 V

V

DD

DD

= 4.75V, IO = –200µA ● 4.0 4.71 V

0V

DD

0V

= 2.7V, IO = –10µA 2.6 V

DD

= 2.7V, IO = –200µA ● 2.3 V

0V

DD

= 4.75V, IO = 1.6mA ● 0.10 0.4 V

0V

DD

= 2.7V, IO = 160µA 0.05 V

0V

DD

0V

= 2.7V, IO = 1.6mA ● 0.10 0.4 V

DD

= 0V, 0VDD = 5V 50 mA

OUT

= VDD, 0VDD = 5V 35 mA

OUT

The ● denotes specifications which apply over the full

● ±10 µA

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POWER REQUIRE E TS

otherwise specifications are at TA = 25°C. Specifications are guaranteed for both dual supply and single supply operation. (Note 4)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V
OV
V

I
I
P

DD

DD

SS

DD

SS

D

Positive Supply Voltage (Note 9) 4.75 5.25 V
Output Supply Voltage (Note 9) 2.7 V
Negative Supply Voltage Dual Supply Mode –5.25 –4.75 V

Positive Supply Current ● 47 60 mA
Negative Supply Current ● 2.3 2.6 mA
Power Dissipation ● 245 300 mW

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

DD

Single Supply Mode 0 V

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TI I G CHARACTERISTICS

range, otherwise specifications are at TA = 25°C. Specifications are guaranteed for both dual supply and single supply operation.
(Note 4)

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

f

SAMPLE

t

CONV

t

ACQ

t

H

t

L

t

AP

t

1

t

2

Sampling Frequency ● 0.05 6 MHz
Conversion Time ● 100 135 ns
Acquisition Time (Note 9) ● 31 67 ns
CLK High Time (Note 9) ● 20 83.3 ns
CLK Low Time (Note 9) ● 20 83.3 ns
Aperature Delay of Sample-and-Hold –900 ps
CLK↑ to BUSY↓ 3.5 ns
BUSY↑ to Outputs Valid 1.5 ns
Data Latency 3 Cycles

The ● denotes specifications which apply over the full operating temperature

V

4

1740f

UW

TI I G CHARACTERISTICS

LTC1740

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 ground with GND and OGND
wired together (unless otherwise noted).

Note 3: When these pin voltages are taken below V

or above VDD, they

SS

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

Note 4: VDD = 5V, VSS = –5V or 0V, f

or above VDD without latchup.

SS

= 6MHz, tr = tf = 5ns unless

SAMPLE

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: Bipolar offset is the offset voltage measured from –0.5LSB
when the output code flickers between 00 0000 0000 0000 and
11 1111 1111 1111.

Note 8: Guaranteed by design, not subject to test.
Note 9: Recommended operating conditions.

otherwise specified.
Note 5: Linearity, offset and full-scale specifications apply for a

single-ended +A

input with –AIN tied to VCM for single supply and 0V for

IN

dual supply.

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Typical INL at 6Msps Typical DNL at 6Msps

2.0

1.5

1.0

0.5

0

INL (LSB)

–0.5

–1.0

–1.5

–2.0

0

4096

8192
CODE

12288

16384

1740 G01

1.0

0.8

0.6

0.4

0.2
0

DNL (LSB)

–0.2
–0.4
–0.6

–0.8

–1.0

0

4096

8192

CODE

12288

16384

1740 G02

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

80

VIN = 0dBFS

75

VIN = –6dBFS

70

65

S/(N + D) (dBc)

VIN = –20dBFS

60

DUAL SUPPLIES
5V INPUT RANGE

55

DIFFERENTIAL INPUT
6Msps

50

0.1

110

INPUT FREQUENCY (MHz)

100

1740 G03

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

80

VIN = 0dBFS

75

VIN = –6dBFS

70

65

S/(N + D) (dBc)

VIN = –20dBFS

60

SINGLE SUPPLY
5V INPUT RANGE

55

DIFFERENTIAL INPUT
6Msps

50

0.1

110

INPUT FREQUENCY (MHz)

1740 G04

100

SFDR and THD
vs Input Frequency

95

90

85

80

75

70

AMPLITUDE (dB)

65

DUAL SUPPLIES
5V INPUT RANGE

60

= 0dBFS

A

IN

DIFFERENTIAL INPUT

55

6Msps

50

0.1
INPUT FREQUENCY (MHz)

SFDR

–THD

1 100

10

1740 G05

SFDR and THD
vs Input Frequency

95

90

85

80

75

70

AMPLITUDE (dB)

65

SINGLE SUPPLY
5V INPUT RANGE

60

= 0dBFS

A

IN

DIFFERENTIAL INPUT

55

6Msps

50

0.1
INPUT FREQUENCY (MHz)

SFDR

–THD

1 100

10

1740 G06

1740f

5