MAX13036 Datasheet, PDF (12/18 Pages) Maxim Integrated Products – Automotive Contact Monitor and Level Shifter

Automotive Contact Monitor
and Level Shifter
STATUS REGISTER
IS COPIED TO
SHIFT REGISTER
CS
SHIFT REGISTER IS
COPIED TO COMMAND
REGISTER
CLK
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
SDI
WTOFF SC2 SC1 SC0 WEN WEND M1 M0 P7 P6 P5 P4 P3 P2 P1 P0
SDO
SW7 SW6 SW5 SW4 SW3 SW2 SW1 SW0 OT * * * * * * *
* = UNUSED.
Figure 5. SPI Read/Write Example
On the falling edge of CS, the status register is immedi-
ately loaded to an internal shift register and the contents
are transferred out of the SDO output on the rising edge
of CLK. Serial data on the SDI input is latched into the
shift register on the falling edge of CLK. On the rising
edge of CS, the contents of the shift register are copied
to the command register (see Figure 5). The status and
command registers are 16 bits wide, so it is essential to
clock a total of 16 bits while CS is low for the input and
output data to be valid. When CS is high, the SDO out-
put is high-impedance and any transitions on CLK and
SDI are ignored. The INT and OT flags are cleared on
the CS falling edge. Input status changes occurring
during the CS reading/writing operation are allowed. If
a switch status changes when CS is low, the interrupt is
asserted as usual. This allows the part to be used even
if V_L is absent provided that the INT output is pulled up
to another supply voltage.
Status Register
The status register contains the status of the switches
connected to IN7 through IN0 and it also contains an
overtemperature warning bit (see Table 1). The status
register is accessed through an SPI-compatible master.
Notes:
Bits 15–8: Switch 7 Through 0 Status (SW7–SW0)
SW7 through SW0 reflect the status of the switches
connected to inputs IN7 through IN0, respectively.
Open switches are returned as a [0] and closed switch-
es are returned as a [1].
Bit 7: Overtemperature Warning (OT)
The OT bit returns a [1] when the internal temperature
of the MAX13036 is above the temperature warning
threshold of +170°C (typ). The OT bit returns a [0]
when the MAX13036 is either below the temperature
threshold, or it has fallen below the temperature hys-
teresis level following an overtemperature event.
Bits 6–0: Unused
Bits 6 through 0 are unused and should be ignored.
Command Register
The command register is used to configure the
MAX13036 for various modes of operation and is
accessed by an SPI-compatible master (see Table 2).
The power-on reset (POR) value of the command regis-
ter is 0x00.
Table 1. Status Register
BIT
15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
NAME SW7 SW6 SW5 SW4 SW3 SW2 SW1 SW0 OT — — — — — — —
Table 2. Command Register
BIT
15
14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
NAME WTOFF SC2 SC1 SC0 WEN WEND M1 M0 P7 P6 P5 P4 P3 P2 P1 P0
POR
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
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