Table of Contents
Advertisement
KPCI-PIO96 User's Manual
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
Boosting relay drive current
Some relays require higher drive currents than standard solid-state relays. The maximum output
low sink current for each I/O line of a KPCI-PIO96 board is 64mA at 5V. If your relay requires
more than 64mA or more than 5V, you can boost the drive current and/or voltage for relay control
using the circuit shown in Figure 3-6.
Figure 3-6
NPN transistor relay control for an output of a KPCI-PIO96 board
Digital
Output
#n
KPCI-PIO96
Board
NPN
Transistor
For drive-current requirements between 15mA and 100mA, select an NPN transistor
with appropriate current capacity. The power transistor must be rated for the required
supply voltage and must have a collector current rating no higher than 0.5A. If higher current
is needed, substitute a Darlington NPN transistor.
Using +5 VDC from the computer power supply
CAUTION
Do not connect the +5 VDC outputs to an external +5VDC supply.
This may damage the external supply, the board, and
the computer.
Do not draw more than 1.0 A, total, from the board to power
external circuits. In other words, do not draw more than 1 A from
pins 49 of all four I/O connectors combined. Drawing more than
1.0 A may damage the board.
The board extends power from the +5 VDC computer supply to at each of the four I/O connectors
(see Figure 3-1). This power is convenient for use in light external circuits, such as pull-up
resistors. If you ensure that the following conditions are maintained, this power may also be
used to energize external accessories:
•
The total current drawn to power the board and all external circuits must not overload the
computer power bus.
•
The total current drawn to power all external circuits (the total current drawn from pins 49
of all connectors) must be less than 1A.
Relay
470 Ω
Min.
Surge
Protection
Digital
Diode
Common
GND
Installation
3-11
+
To Relay
DC Power
Supply
−
Advertisement
Table of Contents
