XRD9825EVAL Datasheet XRD9825ACD-F, XRD9825ACU, XRD9825EVAL | P7-P9

XRD9825

Rev. 1.00

ELECTRICAL CHARACTERISTICS (CONT'D)

Test Conditions: AV

=DV

=5V, ADCCLK=12MHz, 50% Duty Cycle, T

=25°C unless otherwise specified.

Symbol Parameter Min. Typ. Max. Unit Conditions

Digital Output Specifications

Output High Voltage 80 % DV

= 1mA

Output Low Voltage 20 % DV

= -1mA

Output High-Z Leakage Current -10 10 µA

OUT

Output Capacitance 10 pF

SR Slew Rate (10% to 90% DVDD) 2 15 ns CL=10pF, DVDD=3.3V

XRD9825

Rev. 1.00

THEORY OF OPERATION

CIS Configuration (Contact Image Sensor)

The XRD9825 has two configurations for CIS applica-

tions. Each configuration is set by the control registers

accessed through the serial port.

Mode 1. DC Coupled

If the CIS does not have leading or trailing black pixels

as shown in Figure 2, then DC couple the CIS output to

the XRD9825 input.

Optically Shielded

Pixels

Valid Pixels

Figure 2. Typical Output CIS Mode

Adjust the offset of the CIS (-100 mV to 500 mV) by

setting the internal registers of the XRD9825 to set the

black pixel value when the LEDs of the CIS are off.

When the LEDs are on, use the XRD9825 Program-

mable Gain to maximize the ADCs dynamic range.

Figure 3, shows a typical application for a CIS with an

offset of -100mV to 500mV.

XRD9825

Rev. 1.00

The input is added to VRB before the signal passes

through the ADC. If the CIS output is zero, then the

output of the ADC will be zero code. This enables the

CIS to be referenced to the bottom ladder reference

voltage to use the full range of the ADC.

Some CIS sensors have an output with an offset voltage

of greater than 500mV. If the CIS output is beyond the

Figure 3. Application with Offset in the Range (-100mv to 500mv)

VRT

VRB

VDD

RED

XRD9825

N/C

offset range of the XRD9825 (see Offset Control DAC,

Pg. 22) set the internal mode registers to external

reference. An external reference voltage equal to the

value of the CIS offset voltage can be applied to

VDCEXT (Figure 4) in order to meet the dynamic range

of the XRD9825. Figure 4, is a diagram of the XRD9825

in the external reference mode for CIS, DC coupled

applications.

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P21 P22-P24 P25-P27 P28-P30 P31-P33

XRD9825EVAL

Mfr. #:

Buy XRD9825EVAL

Manufacturer:

MaxLinear

Description:

Data Conversion IC Development Tools XRD9825 EVAL BOARD

Lifecycle:

New from this manufacturer.

Delivery:

DHL FedEx Ups TNT EMS

Payment:

T/T Paypal Visa MoneyGram Western Union

XRD9825EVAL

XRD9825EVAL

Products related to this Datasheet