SMH4042A Datasheet, PDF (19/28 Pages) Summit Microelectronics, Inc. – Distributed Power Hot-Swap Controller for CompactPCI

SMH4042A
I/O Buffers
Depending upon the application requirements there are a
number of silicon solutions that employ low on-resistance
CMOS switches. Figure 15 shows one implementation
using a QuickSwitch^® from Quality Semiconductor. This
particular device exhibits very Flat R_ON characteristics
from 0 to 5V. The only drawback is the extra space
required for the external pull-up resistors.
Early Power
SMH4042A
1V_REF
SGNL_VLD#
OE#
An
–
+
LMV321
Bn
Ax
Bx
IDTQS34XVH245
2070 Fig15
Figure 15. Bus Buffers with External Pull-ups
Figure 16 shows another implementation, but the pull-up
resistor structure is incorporated in the switch. The
circuit also automatically switches the bias voltage out of
the circuit as the CMOS switches are enabled. A potential
advantage is the ability to place the interface closer to the
edge of the card. The board designer should evaluate
requirements and design goals to determine the best
solution. The bus switches are available from both Texas
Instruments and Pericom Semiconductor.
Early Power
SMH4042A
1V_REF
SGNL_VLD#
ON#
An
–
+
LMV321
BIASV
Bn
Ax
SN74CBT6800
Bx
or PI5C6800
2070 Fig16
Figure 16. Bus Buffers with Integrated Pull-ups
SUMMIT MICROELECTRONICS, Inc.
2070 9.1 5/27/03
19