ATA6624(2008) 데이터 시트보기 (PDF) - Atmel Corporation

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ATA6624
(Rev.:2008)

LIN Bus Transceiver with 3.3V (5V) Regulator and Watchdog

Atmel Corporation 

ATA6622/ATA6624/ATA6626

5.5 Fail-safe Features

• During a short-circuit at LIN to VBattery, the output limits the output current to IBUS_LIM. Due to

the power dissipation, the chip temperature exceeds TLINoff, and the LIN output is switched

off. The chip cools down and after a hysteresis of Thys, switches the output on again. RXD

stays on high because LIN is high. During LIN overtemperature switch-off, the VCC regulator

works independently.

• During a short-circuit from LIN to GND the IC can be switched into Sleep or Silent Mode. If

the short-circuit disappears, the IC starts with a remote wake-up.

• The reverse current is very low < 15 µA at the LIN pin during loss of VBatt or GND. This is

optimal behavior for bus systems where some slave nodes are supplied from battery or

ignition.

• During a short circuit at VCC, the output limits the output current to IVCCn. Because of

undervoltage, NRES switches to low and sends a reset to the microcontroller. The IC

switches into Fail-safe Mode. If the chip temperature exceeds the value TVCCoff, the VCC

output switches off. The chip cools down and after a hysteresis of Thys, switches the output on

again. Because of the Fail-safe Mode, the VCC voltage will switch on again although EN is

switched off from the microcontroller. The microcontroller can start with its normal operation.

• EN pin provides a pull-down resistor to force the transceiver into recessive mode if EN is

disconnected.

• RXD pin is set floating if VBatt is disconnected.

• TXD pin provides a pull-up resistor to force the transceiver into recessive mode if TXD is

disconnected.

• If TXD is short-circuited to GND, it is possible to switch to Sleep Mode via ENABLE after

tdom > 20 ms (only for ATA6622/ATA6624).

• If the WD_OSC pin has a short-circuit to GND or the resistor is disconnected, the watchdog

runs with an internal oscillator and guarantees a reset after the second NTRIG signal at the

latest.

5.6 Voltage Regulator

The voltage regulator needs an external capacitor for compensation and for smoothing the dis-

turbances from the microcontroller. It is recommended to use an electrolythic capacitor with

C > 10 µF and a ceramic capacitor with C = 100 nF. The values of these capacitors can be var-

ied by the customer, depending on the application.

The main power dissipation of the IC is created from the VCC output current IVCC, which is

needed for the application. In Figure 5-2 on page 14 the safe operating area of the

ATA6622/ATA6624/ATA6626 is shown.

13

4986F–AUTO–07/08

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