FUNCTIONAL DEVICE OPERATION
LOGIC COMMANDS AND REGISTERS
Table 12. OSS SPI Control Commands and Response
Command
Control Address
Command Bits
15
0
14
0
13
0
12
0
11
1
10
X
9
8
7
0
6
0
5
0
4
0
3
0
2
0
1
0
0
0
OSS ON/OFF Command
0 = off, 1 = on
X
X
Open Load Current Enable
0 = disable, 1 = enable
0
0
0
0
0
0
1
1
0
1
X
X
X
X
X
X
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Shutdown/Retry from VPWR Over
Voltage
0 = shutdown, 1 = retry
Shutdown/Retry from Short
Circuit
0
0
1
0
0
X
X
X
1
1
1
1
1
1
1
1
0 = shutdown, 1 = retry
TLim Command
0 = disable, 1 = enable
0
0
0
0
1
1
0
1
1
0
X
X
X
X
X
X
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Fault Timer Command
0 = Fault Timer Disabled
1 = Fault Timer Enabled
Parallel
0
0
0
1
1
0
1
0
1
0
X
X
X
X
X
X
0
0
0
0
0
0
0
0
Outputs(7&8,5&6,3&4,1&2)
Parallel Input Pin Enable
0 = Individual Control, PX enabled
1 = Parallel Control, PX disabled
Output Output Output Output P7 en P5 en P3 en P1 en
7&8
5&6
3&4
1&2
AND/OR Control
0
0
0
0
0
0
0
0
0 = PX Pin OR with SPI
1 = PX Pin AND with SPI
Next SO Response (Message 1)
0 = No Fault, 1 = Fault
OvrVlt Reset Fault Fault Fault Fault Fault Fault Fault Fault Fault Fault Fault Fault Fault Fault
,TLim
or
Statu Statu Statu Statu Statu Statu Statu Statu Statu Statu Statu Statu Statu Statu
sPW sPW sPW sPW sPW sPW sOUT sOUT sOUT sOUT sOUT sOUT sOUT sOUT
CAL
Flt
M6
M5
M4
M3
M2
M1
8
7
6
5
4
3
2
1
faults may not be reported with the pull-down current source
disabled.
ON/OFF CONTROL COMMAND
To program the 8 outputs of the 33800 ON or OFF, a 16-
bit serial stream of data is entered into the SI pin. The first 8-
bits of the control word are used to identify the on/off
command and the remaining 8-bits are used to turn ON or
OFF the specific output driver. When commanding an output
ON or OFF, the Most Significant Bit (MSB) is sent and
received first. Bit 7 corresponds to output 8 down to bit 0
which corresponds to output 1.
OVER-VOLTAGE SHUTDOWN/RETRY COMMAND
The Over Voltage Shutdown/Retry Command allows the
user to select the fault strategy for the outputs. The over-
voltage control bit sets the operation of the outputs when
returning from over-voltage. Setting the over-voltage bit to
logic[0] will force all outputs to remain OFF when VPWR
returns to normal level. Setting the over-voltage bit to logic[1]
will command outputs to resume their previous state when
VPWR returns to normal level.
OPEN LOAD CURRENT ENABLE COMMAND
The Open Load Enable Command is provided to enable or
disable the open load detect pull-down current. This feature
allows the device to be used in LED applications. On power
up reset (POR) or the RESET command the pull-down
current sources are disabled. To enable the open load
current source, the user must program the Open Load
Current Disable Control register with logic[1]. Open load
TLIM COMMAND, TIMER COMMAND
The TLim and Timer commands are used to enhance the
short circuit protection strategy of the Octal Serial Switch
output drivers.
The Timer protection scheme uses a low duty cycle in the
event of a short circuit. The TLim protection circuit uses the
33800
Analog Integrated Circuit Device Data
Freescale Semiconductor
25
FREESCALE [ Freescale ]
