AD9701

–4–

REV. A

FUNCTIONAL DESCRIPTION

Pin Name

Description

GROUND

One of three ground returns. All grounds should be connected together near the AD9701.

Negative supply pin, nominally –5.2 V.

BIT 1 (MSB)

One of eight digital input bits. BIT 1 (MSB) is the most-significant-bit of the digital input word.

BIT 2–BIT 7

One of eight digital input bits.

BIT 8 (LSB)

One of eight digital input bits. BIT 8 (LSB) is the least-significant-bit of the digital input word.

STROBE

Data and control register strobe input. STROBE is leading edge triggered.

GROUND

One of three ground returns. All grounds should be connected together near the AD9701.

SETUP

The SETUP input determines the position of the blanking level relative to the “reference black”

level (all data bits at logic “0”). The setup level is adjustable from 0 IRE units to 20 IRE units be-

low the reference black level (an IRE unit is 1% of the “grey scale” range).

SETUP LEVEL

CONFIGURATION (PIN 21)

0 IRE Units

Ground

7.5 IRE Units

Open

10 IRE Units

Connection to –5.2 V through 1 k

Ω

20 IRE Units

Connection to –5.2 V

10% BRIGHT

10% BRIGHT adds an additional current to the output level, equal to roughly 10% of the “grey

scale” range. The

10% BRIGHT is active logic LOW and operates independently of all other inputs.

COMPOSITE BLANKING

The

COMPOSITE BLANKING input, active logic LOW, forces output to the blanking level set

with the SETUP input.

COMPOSITE SYNC

The

COMPOSITE SYNC input, active LOW, creates a negative going horizontal synchronization

pulse relative to the blanking level. Under normal operating conditions, the

COMPOSITE

BLANKING signal should precede and extend past the COMPOSITE SYNC signal. See SETUP

for additional information.

REFERENCE WHITE

The

REFERENCE WHITE input, active LOW, overrides the data inputs and forces the output to

the maximum “grey scale” level.

COMPENSATION

The COMPENSATION input insures adequate gain stability for the internal reference amplifier.

Under normal operating conditions, the COMPENSATION input is decoupled to ground through

a 0.1

µF capacitor.

CURRENT SET

The CURRENT SET input determines the full-scale or “grey scale” range. The effects of the video

control functions are in addition to the “grey scale” range. (168

Ω ≤ R

≈ 4 I

OUTPUT

Analog output.

GROUND

One of three ground returns. All grounds should be connected together near the AD9701.

SYSTEM TIMING DIAGRAMS