ATA6621-EK Atmel, ATA6621-EK Datasheet - Page 7

• Manufacturer Part Number: ATA6621-EK
• Description: MCU, MPU & DSP Development Tools Demoboard LIN SBC
• Manufacturer: Atmel

2.7
2.8
2.9
4970B–AUTO–03/11
Reset Output (NRES)
KL_15 Input (KL_15) (Atmel ATA6622/24/26 Only)
Inhibit Output (INH) (Atmel ATA6622/24/26 Only)
After ramping up the battery voltage or after a wake-up from Sleep mode, the 5V regulator is
switched on and the VCC voltage exceeds the undervoltage threshold. The implemented
undervoltage delay keeps the NRES output at low level for approximately 10ms after VCC
reaches its nominal value. Then it switches to high and the watchdog waits for the trigger
sequence from the microcontroller.
The NRES pin switches to low if the watchdog is not triggered correctly (see
page
In the ATA6621 the Reset output is a push-pull state supplied by the VCC voltage.
In the Atmel ATA6622/24/26 the Reset output is an open drain output implemented with a sin-
gle MOS transistor which is switched on in case of a VCC undervoltage or if the watchdog is
not triggered correctly. In order to pull up the NRES output of the Atmel ATA6622/24/26 an
external resistor connected to VCC is necessary. This resistor (R9) is taken into account on
the development board.
If a reset occurs (NRES is Low), the circuit switches to Pre-normal mode (Fail-safe mode).
This pin is a high voltage input used to wake up the device from Sleep or Silent mode. It is an
edge sensitive pin (rising edge). It is usually connected to the ignition in order to generate a
local wake-up in the application if the ignition is switched on. To protect the pin against voltage
transients, a series resistor R12 and a 100-nF ceramic capacitor C8 have to be used. If this
pin is not needed, it must be connected to GND.
This pin is a high-side switch and it is normally used to switch on an external voltage regulator
during Normal mode or Fail-safe mode. In Sleep mode or Silent mode the INH output is
switched off.
For master node applications it is possible to switch off the external master resistor (R4) by the
INH pin.
4).
Atmel ATA6621/22/24/26
Section 2.3 on
7