鈩?/div>
termination resistors for VIDEO lines (matched
to 1%聽typ.)
聲 Bi-directional level shifting N-channel FETs provided for
DDC_CLK & DDC_DATA channels
聲 Compact 24-pin QSOP package
24-PIN QSOP PACKAGE
Product Description
The PACVGA200 incorporates 7 channels of ESD protection for all signal lines commonly found in a VGA port. ESD protection
is implemented with current steering diodes designed to safely handle the high surge currents encountered with IEC-1000-4-
2 Level-4 ESD Protection (8KV contact discharge). When a channel is subjected to an electrostatic discharge, the ESD current
pulse is diverted via the protection diodes into the positive supply rail or ground where it may be safely dissipated.
Separate positive supply rails are provided for the VIDEO, DDC and SYNC channels to facilitate interfacing with low voltage
Video Controller ICs and provide design flexibility in multi-supply-voltage environments.
Two non-inverting drivers provide buffering for the HSYNC and VSYNC signals from the Video Controller IC (SYNC1, SYNC2).
These buffers accept TTL input levels and convert them to CMOS output levels that swing between Ground and V
CC4
. These
drivers have nominal 60鈩?output impedance to match the characteristic impedance of the HSYNC & VSYNC lines of the video
cables typically used in PC applications.
Two N-channel FETs provide the level shifting function required when the DDC controller is operated at a lower supply voltage
than the monitor.
Three 75鈩?termination resistors suitable for terminating the video signals from the video DAC are also provided. These
resistors have separate input pins to allow insertion of additional EMI filtering, if required, between the termination point and
the ESD protection diodes. These resistors are matched to better than 2% for excellent signal level matching for the R/G/B
signals.
When the PWR_UP input is driven LOW the SYNC inputs can be floated without causing the SYNC buffers to draw any current
from the V
CC3
supply. When the PWR_UP input is LOW the SYNC outputs are driven LOW.
An internal diode (D1 in schematic below) is also provided so that V
CC3
can be derived from V
CC4
, if desired, by connecting V
CC3
to V_BIAS. In applications where V
CC4
may be powered down, diode D1 blocks any DC current paths from the DDC_OUT pins
back to the powered down V
CC4
rail via the top ESD protection diodes.
Schematic Diagram
漏 2000 California Micro Devices Corp. All rights reserved. PACVGA200聶 is a trademark of California Micro Devices Corp.
4/00
C0641299
215 Topaz Street, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
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