MC33996 View Datasheet(PDF) - Freescale Semiconductor
Part Name
Description
Manufacturer
MC33996 Datasheet PDF : 24 Pages
| |||
LOGIC COMMANDS AND REGISTERS
INTRODUCTION
LOGIC COMMANDS AND REGISTERS
INTRODUCTION
The 33996 provides flexible control of 16 low-side driver
outputs. The device allows PWM and ON /OFF control
through the use of several 24 bit input command words. This
section describes the logic operation and command registers
of the 33996.
The 33996 message set consists of seven messages as
shown in Table 6. Bits 23 through18 determine the specific
command and bits 15 through 0 determine how a specific
output will operate. The 33996 operates on the command
word on the rising edge of CS.
Note Upon Power-ON Reset all bits are defined as shown
in Table 6.
Table 6. SPI Control Commands
MSB
Bits
LSB
Commands
23 22 21 20 19 18
17
16
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
ON/OFF Control
0 = off, 1 = on
000000
X
X
0000000000000000
Open Load Current Enable
0 = disable, 1 = enable
0
0
0
0
0
1
X
X
0000000000000000
Global Shutdown/Retry
Control
0 = shutdown, 1 = retry
Thermal Over-
000010
voltage X X X X X X X X X X X X X X X X
Bit 0
0
SFPD Control
1 = therm only, 0 = VDS
PWM Enable
0 = SPI only, 1 = PWM
000011
X
000100
X
X
1111111111111111
X
0000000000000000
AND/OR Control
0=PWM pin AND with SPI 0 0 0 1 0 1
X
1 = PWM pin OR with SPI
X
0000000000000000
Reset
000110
X
X
XXXXXXXXXXXXXXXX
SO Response
Any over-
volt- 0 0 0 0
0
0=No Fault, 1=Fault
Fault age
OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT OUT
0
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
ON/OFF CONTROL REGISTER
To program the 16 outputs of the 33996 ON or OFF, a 24
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 16 bits are used to turn ON or
OFF the specific output driver.
OPEN LOAD CURRENT ENABLE CONTROL
REGISTER
The Open Load Current Enable Control register is
provided to enable or disable the 50μA open load detect pull-
down current. This feature allows the device to be used in
LED applications. Power-ON Reset (POR) or the RST pin or
the RESET command disables the 50μA pull-down current.
No open load fault will be reported with the pull-down current
disabled. For open load to be active, the user must program
the Open Load Current Enable Control register with logic [1].
GLOBAL SHUTDOWN/RETRY CONTROL
REGISTER
The Global Shutdown/Retry Control register allows the
user to select the global fault strategy for the outputs. The
over-voltage control bit (bit 16) 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. Bit 17 is the global
thermal bit. When bit 17 is set to logic [0], all outputs will shut
down when thermal limit is reached and remain off even after
cooled. With bit 17 set to logic [1], all outputs will shut down
when thermal limit is reached and will retry when cooled.
SHORT FAULT PROTECT DISABLE (SFPD)
CONTROL REGISTER
All outputs contain current limit and thermal shutdown with
programmable retry. The SFPD control bits are used for fast
shutdown of the output when over-current condition is
detected but thermal shutdown has not been achieved.
The SFPD Control register allows the user to select
specific outputs for incandescent lamp loads and specific
outputs for inductive loads. By programming the specific
SFPD bit as logic [1], output will rely on over-temperature
shutdown only. Programming the specific SFPD bit as
logic [0] will shut down the output after 100 to 450μs during
turn on into short circuit. The decision for shutdown is based
Analog Integrated Circuit Device Data
Freescale Semiconductor
33996
13
Share Link: 