Specifications

Section 1. Features and Specifications
5
ENVIRONMENTAL
Printed Circuit Board
21063608 (discontinued)
Printed Circuit Board
21063619 or 21063550
Temperature
Operating
Storage
Units shipped prior to Nov 1, 2003:
32
o
F to 131
o
F (0
o
C to 55
o
C)
Units shipped after Nov 1, 2003:
-4 oF to 158 oF (-20 oC to 70 oC)
-40
o
F to 176
o
F (-40
o
C to 80
o
C)
-40°F to 158°F (-40°C to 70°C)
-40
o
F to 176
o
F (-40
o
C to 80
o
C)
Humidity
Operating
Storage
10% to 90% noncondensing
Up to 100% noncondensing
* The 3.7 mA figure is for continuous data transmission at 33% duty cycle while
reading a card with both heads at once (stripe on each side). Typical capacitance
from TXD is about 1000 pF for our standard 2 m cable. Minimum DTR current ‘I
T
’
required for continuous transmission at 33% duty cycle, while reading a card with
both heads, with cable capacitance ‘C’ is approximately:
I
T
= (3.5 mA) + (10 V) * 33% *(9600 Hz) / 2 * C.
Maximum transmission burst time ‘T’ at 33% duty cycle for RS-232 compatibility is
approximately:
T = (64 μF) * (5 V - 3.4 V) / (I
T
- I
S
), where I
S
is the current supplied by the DTR
line (T is unlimited for I
S
> I
T
)
Subtract 1 mA from I
T
if it is known that both heads will not be used simultaneously (this
is guaranteed on single-head versions).
A note about “port-powered” readers: These readers operate off some combination of otherwise
unused RS-232 lines, DTR and TXD from the host in this case. Per the RS-232 specification,
these lines are only required to drive a 3 kΩ load at +/-5 V. This is a current of merely 5 V / 3
kΩ=1.67 mA per line. All “port-powered” readers fundamentally require more current than 1.67
mA (consider that at least 1.67 mA must be supplied to a 3 kΩ load, and some extra current is
needed for the circuit that does so). Thus these readers are not technically guaranteed to work
unless multiple unused lines are used for power and/or some duty cycle limit is imposed on
transmitting while employing an energy storage device (a capacitor). In practice, however most
ports can easily supply the 2.7 mA at +5 V required by this new reader on DTR and the near-
specification average TXD (from host) current at -5 V. This new reader is MagTek’s lowest
current “port-powered” reader to date. Strictly speaking, some RS-232 ports may not supply the
required current, and this is the reason for including a current consumption specification for a
“port-powered” device. The current drive capability of an RS-232 port is not typically specified,
so experimentation may be required in a particular application. If more current is needed for the
positive supply, RTS may be paralleled with DTR (both host-referenced) in the cabling to the
unit. If this is done, the host must of course hold RTS high.