TECHNICAL NOTES

1. Obtaining fully specified performance from the

ADCDS-1405 requires careful attention to pc-card layout and power

supply decoupling. The device's analog and digital grounds are

connected to each other internally. Depending on the level of digital

switching noise in the overall CCD system, the performance of the AD-

CDS-1405 may be improved by connecting all ground pins (7,32,33,35,

37) to a large analog ground plane beneath the package. The use of a

single +5V analog supply for both the +5VA (pin 36) and +5VD (pin 34)

may also be beneficial.

2. Bypass all power supplies to ground with a 4.7µf tantalum capacitor in

parallel with a 0.1µf ceramic capacitor. Locate the capacitors as close

to the package as possible.

3. If using the suggested offset and gain adjust circuits

(Figure 3 & 5), place them as close to the ADCDS-1405's package as

possible.

4. A0 and A1 (pins 30, 31) should be bypassed with 0.1µf capacitors to

ground to reduce susceptibility to noise.

ADCDS-1405 Modes of Operation

The input amplifier stage of the ADCDS-1405 provides the designer with

a tremendous amount of flexibility. The architecture of the ADCDS-1405

allows its input-amplifier to be configured in any of the following

configurations:

• Direct Mode (AC coupled)

• Non-Inverting Mode

• Inverting Mode

When applying inputs which are less than 2.8Vp-p, a coarse gain

adjustment (applying an external resistor to pin 4) must be performed to

ensure that the full scale video input signal (saturated signal) produces a

2.8Vp-p signal at the input-amplifier's output (Vout).

In all three modes of operation, the video portion of the signal at the CDS

input (i.e. input-amplifier's Vout) must be more negative than its associated

reference level and Vout should

not exceed ±2.8V DC.

The ADCDS-1405 achieves it specified accuracies without the need for

Figure 2a.

Figure 2b.

4

3

5

75

�

523

�

NO CONNECT

5k

�

0.01µF

Rext

4

3

5

75

�

523

�

NO CONNECT

5k

�

0.01µF

Rext

Figure 2c.

4

3

5

75

�

523

�

NO CONNECT

5k

�

0.01µF

POWER REQUIREMENTS

MIN.

TYP.

MAX.

UNITS

Power Supply Current

+12V Supply

—

+20

+26

mA

Power Supply Current

-5V Supply

+5V Supply

—

—

-40

+50

-45

+56

mA

mA

Power Dissipation

—

0.7

0.9

Watts

Power Supply Rejection

(5%) @ +25°C

—

±0.04

±0.06

%FSR/%V

ENVIRONMENTAL

Operating Temperature Range

ADCDS-1405

0

—

+70

°C

ADCDS-1405EX

–55

—

+100

°C

Storage Temperature

–65

—

+150

°C

Package Type

40-pin, TDIP

Weight

16.10 grams

external calibration. If required, the device's small initial offset and gain

errors can be reduced to zero using the FINE GAIN ADJUST (pin1) and

OFFSET ADJUST (pin 2) features.

Direct Mode (AC Coupled)

This is the most common input configuration as it allows the

ADCDS-1405 to interface directly to the output of the CCD with a

minimum amount of analog "front-end" circuitry. This mode of operation

is used with full-scale video input signals from 0.350Vp-p to 2.8Vp-p.

Figure 2a. describes the typical configuration for applications using a

video input signal with a maximum amplitude of 0.350Vp-p. The coarse

gain of the input amplifier is determined from the following equation:

VOUT = 2.8Vp-p = VIN*(1+(523/75)), with all internal resistors having

a 1% tolerance. Additional fine gain adjustment can be accomplished

using the Fine Gain Adjust (pin 1 see Figure 5).

Figure 2b. describes the typical configuration for applications using a

video input signal with an amplitude greater than 0.350Vp-p and less

than 2.8Vp-p. Using a single external series resistor (see Figure 4.), the

coarse gain of the ADCDS-1405 can be set, with additional fine gain

adjustments being made using the Fine Gain Adjust function (pin 1 see

Figure 5). The coarse gain of the input amplifier can be determined from

the following equation:

VOUT = 2.8Vp-p = VIN*(1+(523/(75+Rext))), with all internal resistors

having a 1% tolerance.

ADCDS-1405

14-Bit, 5 Megapixels/Second, CCD Signal Processor

www.murata-ps.com

MDC_ADCDS-1405.B02 Page 3 of 9