VSP2264GSJR datasheet(21/63 Pages) TI

21 / 63 page

Theory of Operation

SLES059—March 2003

VSP2264

2.11 Power-Save Mode

For the purpose of power savings, the VSP2264 can be put into the power-save plus standby mode by serial

interface command. In this mode, all the function blocks are disabled, the A/D outputs all go to zero and the

TG output goes to high or low status as determined by the configuration of the serial interface command. The

power consumption drops to 39 mW. Because all the bypass capacitors discharge during this mode, a

substantial time (usually on the order of 200–300 ms) is required to restore from the power-save plus standby

mode.

2.12 Additional Output Delay Control

The VSP2264 can control the delay time of output data by setting registers through the serial interface. In some

cases, the transition of output data affects analog performance. Generally, this is avoided by adjusting the

timing of ADCCK. In case the ADCCK timing cannot be adjusted, the additional output delay control is effective

for reducing the influence of transient noise. Refer to the Serial Interface Timing Specification (Section 3) for

details.

2.13 Voltage Reference

All the reference voltages and bias currents used on the device are created from internal band-gap circuitry.

The CDS and the ADC mainly use three reference voltages, REFP (1.75 V), REFN (1.25 V) and CM (1.5 V).

REFP and REFN are buffered on-chip. CM is derived as the midvoltage of the resistor chain connecting REFP

and REFN internally. The ADC full-scale range is determined by twice the voltage difference between REFP

and REFN.

REFP, REFN, and CM should be heavily decoupled with appropriate capacitors.

Table 2–1. Function Table

OPERATION MODE

FUNCTION

5A CCD†

FUNCTION

FRAME

MONITOR

LONG INTEGRATION (CHDEL)

√

POWER SAVE (PWSV)

√

STILL (STIL)

√

E-SHUTTER

√

† Recommended CCD MN39594 (Panasonic)

2.14 Operating Modes

•

Frame mode enables each pixel output with interlace.

•

Monitor mode enables the output of four from every 16 lines.

2.15 Functions

•

The long integration function stops CCD readout (CH1, CH2, CH3, CH4 pulse) at the end of one frame,

as defined by the serial data instruction.

•

The power save function stops all clocks and preserves high or low levels according to the serial data

instruction.

•

The e-shutter function enables electronic shutter operation by the serial data instruction.

VSP2264GSJR Datasheet(PDF) 21 Page - Texas Instruments

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