11

LTC1564

1564fa

TYPICAL APPLICATIO S

16-Bit Output, Sampling Rate to 500ksps, Analog Bandwidth to 150kHz, Gain to 24dB.

(For More Information, See

Linear Technology Magazine, May 2001)

2-Chip Flexible DSP Front End with Amplification,

Antialias Filtering and A/D Conversion

Boosting a 100mVRMS Input Signal to Nearly Fill the Input Range of the LTC1608 ADC. Input Frequency of 40kHz,

LTC1608 fSAMPLE = 204.8ksps, LTC1564 is Set for fC = 50kHz and Gain of 16 (F = 0101, G = 1111). Measured THD

is 86dB, HD2 = – 88dB, SNR = 85dB with 100mVRMS Input. Dynamic Range of Approximately 115dB

4096-Point FFT Spectrum

with Low Level Input

FREQUENCY (kHz)

0

–60

–40

0

76.8

1564 TA04

–80

–100

25.6

51.2

102.4

–120

–140

–20

2.2

µF

1

µF

1

µF

10

Ω

22

µF

4

6

DIFFERENTIAL

ANALOG INPUT

±2.5V

REFCOMP

CONTROL

LOGIC

AND

TIMING

B15 TO B0

16-BIT

SAMPLING

ADC

–

+

1

µF

5V OR

3V

µP

CONTROL

LINES

D15 TO D0

OUTPUT

BUFFERS

16-BIT

PARALLEL

BUS

11 TO 26

OGND

OVDD

28

1564 TA03

29

1

2

AIN

+

AIN

–

SHDN

CS

CONVST

RD

BUSY

33

32

31

30

27

7.5k

LTC1608

3

36

35

10

9

5V

5V

AVDD

AVDD

DVDD

DGND

VREF

8

AGND

AGND

7

AGND

5

AGND

34

–5V

VSS

1

µF

2.5V

REF

1

µF

1.75X

+

V+ EN V–

OUT

AGND

IN

16

CS/

HOLD RST

F

4

5 6 7 8

9 10 11 12

15

1

2

3

14

13

G

LTC1564

5V

–5V

0.1

µF

0.1

µF

249

Ω

1% METAL FILM

249

Ω

1% METAL FILM

C1*

FILTER CONTROL

ANTIALIAS FILTER/AMP

ADC

AV

fC

INPUT

+

–

*C1 IS A 1000pF NPO, SURFACE MOUNT DEVICE

PLACE AS CLOSE AS POSSIBLE TO THE LTC1608 INPUT PINS

AV

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 represen-

tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.