XRD98L23ACU Datasheet XRD98L23ACU, XRD98L23ACU-F, XRD98L23ACD-F | P7-P9

XRD98L23

Rev. 1.00

ELECTRICAL CHARACTERISTICS (CONT'D)

Test Conditions: AV

=DV

=3.3V, ADCCLK=10MHz, 50% Duty Cycle, T

=25°C unless otherwise specified.

Symbol Parameter Min. Typ. Max. Unit Conditions

Digital Output Specifications

Output High Voltage 80

(

%) DVDD

= 1mA

Output Low Voltage 20

(

%) DVDD

= -1mA

Output High-Z Leakage Current -10 10 µA

OUT

Output Capacitance 10 pF

SR Slew Rate (10% to 90% DV

) 2 15 ns C

= 10pF, DV

= 3.3V

XRD98L23

Rev. 1.00

THEORY OF OPERATION

CIS Configuration (Contact Image Sensor)

The XRD98L23 has two configurations for CIS applications. 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

XRD98L23 input.

Optically Shielded

Pixels

Valid Pixels

Adjust the offset of the CIS (-60 mV to 300 mV) by setting the internal registers of the XRD98L23 to set the black

pixel value when the LEDs of the CIS are off. When the LEDs are on, use the XRD98L23 Programmable Gain to

maximize the ADCs dynamic range. Figure 3 shows a typical application for a CIS with an offset of -60mV to 300mV.

Figure 2. Typical Output CIS Mode

XRD98L23

Rev. 1.00

VRT

VRB

VDD

RED

XRD98L23

N/C

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 300mV. If the CIS output is beyond the

offset range of the XRD98L23 (see Offset Control DAC,

Pg. 27) 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 XRD98L23. Figure 4 is a diagram of the

XRD98L23 in the external reference mode for CIS, DC

coupled applications.

Figure 3. Application with Offset in the Range (-60mv to 300mv)

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P21 P22-P24 P25-P27 P28-P30 P31-P32

XRD98L23ACU

Mfr. #:

Buy XRD98L23ACU

Manufacturer:

MaxLinear

Description:

Analog Front End - AFE

Lifecycle:

New from this manufacturer.

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XRD98L23ACU

XRD98L23ACU

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