1

LTC1745

1745f

APPLICATIO S

FEATURES

DESCRIPTIO

BLOCK DIAGRA

Low Noise,12-Bit, 25Msps ADC

s

Sample Rate: 25Msps

s

72.5dB SNR and 91dB SFDR (3.2V Range)

s

71dB SNR and 96dB SFDR (2V Range)

s

No Missing Codes

s

Single 5V Supply

s

Low Power Dissipation: 380mW

s

Selectable Input Ranges:

±1V or ±1.6V

s

240MHz Full Power Bandwidth S/H

s

Pin Compatible Family

25 Msps: LTC1746 (14-Bit), LTC1745 (12-Bit)

50 Msps: LTC1744 (14-Bit), LTC1743 (12-Bit)

65 Msps: LTC1742 (14-Bit), LTC1741 (12-Bit)

80 Msps: LTC1748 (14-Bit), LTC1747 (12-Bit)

s

Telecommunications

s

Medical Imaging

s

Receivers

s

Base Stations

s

Spectrum Analysis

s

Imaging Systems

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

The LTC

verter designed for digitizing high frequency, wide dy-

namic range signals. Pin selectable input ranges of

±1V

and

±1.6V along with a resistor programmable mode

allow the LTC1745’s input range to be optimized for a wide

variety of applications.

The LTC1745 is perfect for demanding communications

applications with AC performance that includes 72.5dB

SNR and 91dB spurious free dynamic range. Ultralow jitter

performance. DC specs include

±1LSB INL maximum and

±0.75LSB DNL over temperature.

The digital interface is compatible with 5V, 3V and 2V logic

systems. The ENC and ENC inputs may be driven differen-

tially from PECL, GTL and other low swing logic families or

from single-ended TTL or CMOS. The low noise, high gain

ENC and ENC inputs may also be driven by a sinusoidal

signal without degrading performance. A separate digital

output power supply can be operated from 0.5V to 5V,

making it easy to connect directly to low voltage DSPs

or FIFOs.

The TSSOP package with a flow-through pinout simplifies

the board layout.

25Msps, 12-Bit ADC with a

±1V Differential Input Range

12-BIT

PIPELINED ADC

12

S/H

AMP

±1V

DIFFERENTIAL

ANALOG INPUT

+

–

SENSE

4.7

µF

DIFF AMP

REFLA

REFHB

GND

1745 BD

ENC

4.7

µF

1

µF1µF

0.1

µF

0.1

µF

REFHA

REFLB

BUFFER

RANGE

SELECT

OUTPUT

LATCHES

CONTROL LOGIC

OGND

0.5V TO 5V

5V

0.1

µF

1

µF

1

µF

1

µF

D11

D0

CLKOUT

OF

•

•

•

ENC

DIFFERENTIAL

ENCODE INPUT

OE

MSBINV

0.1

µF