SPT7863SCS データシートの表示（PDF） - Signal Processing Technologies

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SPT7863SCS

10-BIT, 40 MSPS,160 mW A/D CONVERTER

Signal Processing Technologies 

Figure 4 - Recommended Input Protection Circuit

+V

AVDD

Buffer

D1

47 Ω

D2

ADC

-V

D1 = D2 = Hewlett Packard HP5712 or equivalent

Figure 5 - On-Chip Protection Circuit

VDD

120 Ω

Analog

120 Ω

Pad

CLOCK INPUT

The SPT7863 is driven from a single-ended TTL-input clock.

Because the pipelined architecture operates on the rising edge of

the clock input, the device can operate over a wide range of input

clock duty cycles without degrading the dynamic performance.

DIGITAL OUTPUTS

The digital outputs (D0-D10) are driven by a separate supply

(OVDD) ranging from +3 V to +5 V. This feature makes it

possible to drive the SPT7863's TTL/CMOS-compatible out-

puts with the user's logic system supply. The format of the

output data (D0-D9) is straight binary. (See table III.) The

outputs are latched on the rising edge of CLK. These outputs

can be switched into a tri-state mode by bringing EN high.

Table III - Output Data Information

ANALOG INPUT

+F.S. + 1/2 LSB

OVERRANGE

D10

1

OUTPUT CODE

D9-D0

11 1111 1111

+F.S. -1/2 LSB

O

11 1111 111Ø

+1/2 F.S.

O

ØØ ØØØØ ØØØØ

+1/2 LSB

O

OO OOOO OOOØ

0.0 V

O

OO OOOO OOOO

(Ø indicates the flickering bit between logic 0 and 1).

OVERRANGE OUTPUT

The OVERRANGE OUTPUT (D10) is an indication that the

analog input signal has exceeded the positive full scale input

voltage by 1 LSB. When this condition occurs, D10 will switch

to logic 1. All other data outputs (D0 to D9) will remain at

logic 1 as long as D10 remains at logic 1. This feature makes

it possible to include the SPT7863 into higher resolution

systems.

EVALUATION BOARD

The EB7863 evaluation board is available to aid designers in

demonstrating the full performance of the SPT7863. This

board includes a reference circuit, clock driver circuit, output

data latches and an on-board reconstruction of the digital

data. An application note describing the operation of this

board as well as information on the testing of the SPT7863 is

also available. Contact the factory for price and availability.

SPT

7

SPT7863

4/30/98

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