FUNCTIONAL DESCRIPTION
TIMING DIAGRAMS
INHIBIT OUTPUT PIN (INH)
The INH pin controls an external switchable voltage
regulator having an inhibit input. This pin is a high-side switch
structure to VSUP. When the device is in the Normal mode,
the inhibit high-side switch is turned ON and the external
voltage regulator is activated. When the device is in Sleep
mode, the inhibit switch is turned OFF and disables the
voltage regulator (if this feature is used).
A wake-up event on the LIN bus line will switch the INH pin
to VSUP level. Wake-up output current capability is limited to
280 µA. INH can also drive an external MOSFET connected
to an MCU IRQ or XIRQ input to generate an interrupt. See
the typical application illustrated in Figure 13, page 15.
WAKE INPUT PIN (WAKE)
The WAKE pin is a high-voltage input used to wake up the
device from Sleep mode. WAKE is usually connected to an
external switch in the application. The typical WAKE
thresholds are VSUP/2.
The WAKE pin has a special design structure and allows
wake-up from both HIGH-to-LOW or LOW-to-HIGH
transitions. When entering the Sleep mode, the LIN monitors
the state of the WAKE pin and stores it as a reference state.
The opposite state of this reference state will be the wake-up
event used by the device to re-enter Normal mode.
An internal filter is implemented (50 µs typical filtering time
delay). The WAKE pin input structure exhibits a high
impedance with extremely low input current when voltage at
this pin is below 14 V. When voltage at the WAKE pin
exceeds 14 V, input current starts to sink into the device. A
series resistor should be inserted in order to limit the input
current, mainly during transient pulses. Recommended
resistor value is 33 kΩ.
Important The WAKE pin should not be left open. If the
wake-up function is not used, WAKE should be connected to
GND to avoid false wake-up.
33399
Analog Integrated Circuit Device Data
Freescale Semiconductor
11
FREESCALE [ Freescale ]
