Itron 0001 ユーザーズマニュアル
July 23, 2002
4-11
CreataLink2 XT Hardware Integrator’s Guide
Hardware Integration
Host Interface
Effect of I/O on Operating Current
The specification for the CreataLink2 XT device transmit current is 1400 mA.
However, if an application is to use the parallel I/O capabilities, this number could
nearly double. As a result, you should take into account the I/O when you design
the system power supply.
However, if an application is to use the parallel I/O capabilities, this number could
nearly double. As a result, you should take into account the I/O when you design
the system power supply.
Open Collector I/O
As noted earlier, the open collector lines are capable of sinking 25 mA each. This
current comes from the pull-up voltage, which may or may not be the same supply
voltage as that applied to pin 1 of the 22-pin connector. If this is the same supply
voltage as the primary supply voltage applied to the CreataLink2 XT device, then
you must account for this current.
current comes from the pull-up voltage, which may or may not be the same supply
voltage as that applied to pin 1 of the 22-pin connector. If this is the same supply
voltage as the primary supply voltage applied to the CreataLink2 XT device, then
you must account for this current.
Worst case occurs when all six open collector outputs are driven low and are sinking
the maximum allowable current of 25 mA. This could result in as much as 150 mA
additional to the 1400 mA transmit current.
the maximum allowable current of 25 mA. This could result in as much as 150 mA
additional to the 1400 mA transmit current.
Driven I/O
If the driven outputs are each sourcing their maximum current of 350 mA each,
then 700 mA must be added to the 1400 mA transmit current.
then 700 mA must be added to the 1400 mA transmit current.
In the worst case, the CreataLink2 XT device is transmitting, while sinking the
maximum allowable for the open collector outputs, and sourcing the maximum
allowable with the driven output. This could bring the maximum peak current to
1400 + 6*25 + 2*350 = 2250 mA. SmartSynch, Inc. recommends at least a 2.5A
supply in this case.
maximum allowable for the open collector outputs, and sourcing the maximum
allowable with the driven output. This could bring the maximum peak current to
1400 + 6*25 + 2*350 = 2250 mA. SmartSynch, Inc. recommends at least a 2.5A
supply in this case.
The I/O current is a constant current and does not go down when the
CreataLink2 XT device is placed in the sleep mode. In this case, the worst case sleep
current would be 5 + 6*25 + 2*350 = 855 mA, with no valid RS-232 voltages present.
CreataLink2 XT device is placed in the sleep mode. In this case, the worst case sleep
current would be 5 + 6*25 + 2*350 = 855 mA, with no valid RS-232 voltages present.
RX_Active and TX_Active Signal Behaviors
ReFLEX is a half-duplex, TDMA signalling protocol which means that the data
transceiver can either receive or transmit but not simultaneously. The TDMA
aspect means that the system uses time slots for synchronization in a manner
similar to a GSM system. In a ReFLEX system, the base timeslot is a 1.875 second
time slice, referred to as a frame. The data transceiver will wake up at the beginning
of a frame to listen to the channel and determine if there is a message in that frame
intended for that data transceiver.
transceiver can either receive or transmit but not simultaneously. The TDMA
aspect means that the system uses time slots for synchronization in a manner
similar to a GSM system. In a ReFLEX system, the base timeslot is a 1.875 second
time slice, referred to as a frame. The data transceiver will wake up at the beginning
of a frame to listen to the channel and determine if there is a message in that frame
intended for that data transceiver.
In order to provide a lower average current, a method has been developed which
allows the receiver to be powered off for portions of time. A parameter named
Battery Save Cycle or Frame Collapse is provided which determines how often the
data transceiver has its receiver powered up. The data transceiver will power up
its receiver every (1.875 * (2
allows the receiver to be powered off for portions of time. A parameter named
Battery Save Cycle or Frame Collapse is provided which determines how often the
data transceiver has its receiver powered up. The data transceiver will power up
its receiver every (1.875 * (2
Collapse
)) seconds. For example, if the collapse is set to
3, then the data transceiver will power up its receiver every 8 frames or 15 seconds
to look for a message. Each time the receiver is powered up, the RX_Active signal
is activated. When the receiver is subsequently powered down, the RX_Active signal
is correspondingly deactivated.
to look for a message. Each time the receiver is powered up, the RX_Active signal
is activated. When the receiver is subsequently powered down, the RX_Active signal
is correspondingly deactivated.