33899 Datasheet, PDF (22/26 Pages) Freescale Semiconductor, Inc – Programmable H-Bridge Power IC

FUNCTIONAL DEVICE OPERATION
LOGIC COMMANDS AND REGISTERS
LOGIC COMMANDS AND REGISTERS
SPI INTERFACE AND REGISTER DESCRIPTION
SPI Control Register Definition
An 8-bit SPI allows the system microprocessor to clear the
Fault register, select a programmable current limit, and select
a 1X, 2X, or 4X slew rate. The SPI Control Register bit
definitions are shown in Table 8.
Note At POR, all bits in the register are cleared to 0s.
Table 8. SPI Control Register Bit Definitions
8 (MSB)
7
6
5
4
3
FLTCLR
Not Used
Not Used
Not Used Current Limit Current Limit
Bit 8: FLTCLR: 0 = Retain faults; 1 = Clear faults
Bit 7: Not used
Bit 6: Not used
Bit 5: Not used
Bits 4 – 3: Set Low Side Current Comparator Limits
00 = 4.0A
01 = 5.0A
10 = 6.0A
11 = 8.5A
Bits 2 – 1: Slew Time
00 = 1X
01 = 2X
10 = 4X
11 = 4X
2
Slew Time
1 (LSB)
Slew Time
SPI Fault Register Definition
The fault diagnostic capability consists of one internal 8-bit
Fault register. Table 9 shows the content of the Fault register.
The output load status of the H-Bridge circuit is reported via
the output DO SPI bits. In addition to output fault information,
die temperature warnings and over-temperature conditions
are reported.
An SPI read cycle is limited by a CS logic [1] to logic [0]
transition, followed by 8 SCLK cycles to shift the fault register
bits out the DO pin. The rising edge of CS sets DO in a high-
impedance mode and clears the fault latches if the FLTCLR
bit is set. The thermal fault is immediately set again if the fault
condition is still present. Accurate fault reporting can only be
obtained by reading the DO line at intervals greater than the
fault timer. A thermal fault will be latched as soon as it occurs.
Note: At POR, all bits in the register are cleared to 0s.
Table 9. SPI Fault Register Bit Definitions
8 (MSB)
7
6
5
4
3
2
ShVIGNP
ShGnd
Open Fault
Over-voltage or
Under-voltage
LS Comparator
EN1, EN2
Status
Die Temp
Bit 8: Short to VIGNP: 0 = No fault; 1 = S1 or S0 shorted to VIGNP (Low Side Linear Current Limit has tripped)
Bit 7: Short to Ground: 0 = No fault; 1 = S1 or S0 shorted to GND (High Side Linear Current Limit has tripped)
Bit 6: Open Fault: 0 = No fault; 1 = S1 or S0 is Open Circuited
Bit 5: Over-voltage or Under-voltage: 0 = No fault; 1 = Over-voltage/under-voltage fault
Bit 4: Low Side Comparator: 0 = No trip; 1 = Tripped
Bit 3: XOR function of EN1, EN2 inputs. 0 = (EN1 same logic level as EN2). 1 = (EN1 not same logic level as EN2).
Bits 2 – 1: Die Temperature
00 = T < 140°C
01 = 140°C < T < Over-temperature Shutdown
10 = Not Defined
11 = Over-temperature Shutdown (Latched Off)
1 (LSB)
Die Temp
33899
22
Analog Integrated Circuit Device Data
Freescale Semiconductor