BTS54040-LBB_15 Datasheet, PDF (23/67 Pages) Infineon Technologies AG – SPI Power Controller

BTS54040-LBB
Power Supply
5.1.4 Ready mode
In Ready mode, one or more outputs received a command to switch ON (either via SPI or via Input pins).
Nevertheless all outputs are OFF because of DCR.MUX bits still set to 111_B. It is necessary to change the value of
those bits to bring the device into Operative mode and switch ON the channels.
5.1.5 Operative mode
Operative mode is the normal operation mode of BTS54040-LBB when no Limp Home condition is set and one or
more outputs are switched ON. Device current consumption is specified by parameter I_GND. An undervoltage
condition on V_DD supply voltage brings the device into Stand-by mode (if all Input pins are set to “low”) or into
Ready mode (if at least one Input pin is set to “high”).
5.1.6 Limp Home mode
BTS54040-LBB enters Limp Home mode when LHI pin is set to “high”. SPI registers are reset to the default values
after t_LHI(ac) from the rising edge at pin LHI (see Figure 11 for further details). SPI communication is possible but
only in read-only mode (SPI registers can be read but cannot be written, meaning that current sensing is not
available). When V_S ≤ V_SMON and DCR.MUX ≠ 111_B the logic state detected at pin LHI is ignored and the device
doesn’t enter Limp Home mode.
Note: The only write commands excepted in Limp Home mode are HWCR.CTC and HWCR.RST to clear the
protection latches.
VS
VSMON
LHI
pin
t < t_{LHI(ac), min}
t < t_{LHI(ac), min}
LHI
bit
SPI state
t LHI(ac)
Normal operation
Reset
t LHI(ac )
Normal operation
Figure 11 Limp Home Activation as function of V_S
PowerSupply_LimpHomeActive.emf
5.2
Reset condition
One of the following 3 conditions resets the SPI registers to their default values:
• V_DD is not present or below the undervoltage threshold V_DD(PO)
• LHI pin is set to “high” and V_S > V_SMON
• a reset command (HWCR.RST = 1_B) is executed
In particular, all channels are switched OFF (if the device is not in Limp Home mode with one or more Input pins
set to “high”). In case of lack of V_DD supply the internal retry counters are disabled therefore all channels are in
“unlimited restart” mode.
Data Sheet
23
Rev. 2.1, 2014-12-05