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PDF ATA6621 Data sheet ( Hoja de datos )
| Número de pieza | ATA6621 | |
| Descripción | LIN Transceiver | |
| Fabricantes | ATMEL Corporation | |
| Logotipo |  |
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Features
• Supply Voltage up to 40V
• Operating Voltage VS = 5V to 18V
• Slew Rate Control according to LIN Specification 2.0
• Supply Current during Sleep Mode Typically 10 µA
• Supply Current in Silent Mode Typically 40 µA
• Linear Low-drop Voltage Regulator:
– Normal Mode: VCC = 5V ±2%/50 mA
– Silent Mode: VCC = 5V ±7%/50 mA
– Sleep Mode: VCC is Switched Off
• VCC Undervoltage Detection (10 ms Reset time) and Watchdog Reset Logically
Combined at Output NRES
• Possibility of Boosting the Voltage Regulator with an External NPN Transistor
• LIN Physical Layer according to LIN Specification 2.0
• Wake-up Capability via LIN Bus or WAKE Pin
• Wake-up Recognition
• TXD Time-out Timer
• 60V Load Dump Protection at LIN Pin
• Bus Pin is Overtemperature and Short Circuit Protected versus GND and Battery
• Adjustable Watchdog Time via External Resistor
• Positive and Negative Trigger Input for Watchdog
• 5V CMOS Compatible I/O Pins to MCU
• Analog Temperature Monitor Output
• High EMC and ESD Level
• Package: QFN 5 × 5 with 20 Pins
LIN Transceiver
with 5V
Regulator and
Watchdog
ATA6621
1. Description
The ATA6621 is a fully integrated LIN transceiver, complying with the LIN specifica-
tion, and with a low-drop voltage regulator for 5V/50 mA output and a window
watchdog adjustable via an external resistor. In this QFN20 package, the voltage reg-
ulator is able to source 50 mA at VS = 18V even at an ambient temperature of 105°C.
The output current of the regulator can be boosted by using an external NPN transis-
tor. This combination makes it possible to develop simple, but powerful and cheap,
slave nodes in LIN bus systems. ATA6621 is designed to handle the low speed data
communication in vehicles, for example, in convenience electronics. Improved slope
control at the LIN driver ensures secure data communication up to 20 kBaud. The bus
output is capable of withstanding 60V. Sleep Mode and Silent Mode guarantee a very
low current consumption.
Rev. 4887B–AUTO–01/06
1 page  
ATA6621
3.7 TXD Dominant Time-out Function
The TXD input has an internal pull-up resistor. An internal timer prevents the bus line from being
driven permanently in the dominant state. If TXD is forced to low longer than tDOM > 20 ms, the
LIN bus driver is switched to the recessive state.
3.8 Output Pin (RXD)
This pin reports the state of the LIN bus to the microcontroller. LIN high (recessive state) is
reported by a high level at RXD, LIN low (dominant state) is reported by a low level at RXD. The
output has an internal pull-up structure with typically 5 kΩ to VCC. The AC characteristics can be
defined with an external load capacitor of 20 pF.
The output is short-circuit protected. In Unpowered Mode (that is, VS = 0V), RXD is switched off.
3.9 Enable Input Pin (EN)
This pin controls the operation mode of the interface. If EN is high, the interface is in Normal
Mode, with transmission paths from TXD to LIN and from LIN to RXD both being active. The VCC
voltage regulator is operating with 5V ±2%/50 mA output capability.
If EN is switched to low while TXD is still high, the device is forced to Silent Mode. No data trans-
mission is then possible and the current consumption is reduced to IVS = 50 µA. The current
capability of the VCC regulator is also 50 mA, but the VCC tolerance is between 4.65V and 5.35V.
If EN is switched to low while TXD is low, the device is forced to Sleep Mode. No data transmis-
sion is possible and the voltage regulator is switched off.
3.10
Wake Input Pin (WAKE)
This pin is a high voltage input used to wake the device up from Sleep Mode. It is usually con-
nected to an external switch in the application to generate a local wake-up. A pull-up current
source with typically 10 µA is implemented.
If you don’t need a local wake-up in your application, connect pin WAKE directly to pin VS.
3.11
MODE and TM Input Pins
These inputs are used for a special test mode of the watchdog in final production measurement
at Atmel. In the application, they are always connected to GND.
Wake-up events from Sleep Mode:
• LIN bus
• WAKE pin
• EN pin
4887B–AUTO–01/06
5
5 Page 
ATA6621
3.13 Wake-up Scenarios
3.13.1
3.13.2
3.13.3
Remote Wake-up via Dominant Bus State
A falling edge at pin LIN followed by a dominant bus level maintained for a certain time period
(TBUS) results in a remote wake-up request. The device switches to Pre Normal Mode. The VCC
voltage regulator is activated, and the internal slave termination resistor is switched on. The
remote wake-up request is indicated by a low level at pin RXD to generate an interrupt in the
microcontroller. The watchdog needs a trigger signal from PTRIG or NTRIG within the lead time
tD to avoid resets at NRES. (Figure 3-2 on page 7)
Local Wake-up via Pin Wake
A falling edge at pin WAKE followed by a low level maintained for a certain time period (TWAKE)
results in a local wake-up request. The extra long wake-up time (TWAKE) ensures that no tran-
sients as defined in ISO7637 create a wake-up. The device switches to Pre Normal Mode. The
internal slave termination resistor is switched on. The local wake-up request is indicated by a low
level at pin RXD to generate an interrupt in the microcontroller. The watchdog needs a trigger
signal from PTRIG or NTRIG within the lead time tD to avoid resets at NRES.
Wake-up Source Recognition
The device can distinguish between a local wake-up request (pin WAKE) and a remote wake-up
request (dominant LIN bus state). The wake-up source can be read on pin TXD in Pre Normal
Mode. If an external pull-up resistor (typically 5 kΩ) on pin TXD to the power supply of the micro-
controller has been added, a high level indicates a remote wake-up request (weak pull down at
pin TXD) and a low level indicates a local wake-up request (strong pull down at pin TXD). The
wake-up request flag (signalled on pin RXD) as well as the wake-up source flag (signalled on pin
TXD) are reset immediately, if the microcontroller sets pin EN to high (Figure 3-2 on page 7 and
Figure 3-3 on page 8).
3.14
Fail-safe Features
• During a short circuit at LIN, 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. During LIN
overtemperature switch-off, the VCC regulator works independently.
• The reverse current at pin LIN is very low (< 3 µA) during loss of VBAT or GND. This is optimal
behavior for bus systems where some slave modes 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 Pre Normal 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 Pre Normal Mode, the VCC voltage will switch on again although EN is
switched off from the microcontroller. The microcontroller can start its normal operation.
• Pin EN provides a pull-down resistor to force the transceiver into recessive mode if EN is
disconnected.
• Pin RXD is set floating if VBat is disconnected.
• Pin TXD provides a pull-up resistor to force the transceiver into recessive mode if TXD is
disconnected.
• If the WD_OSC pin has a short circuit to GND or the resistor is disconnected, the watchdog
oscillator runs with a high frequency and guarantees a reset in any condition.
4887B–AUTO–01/06
11
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| Páginas | Total 26 Páginas | |
| PDF Descargar | [ Datasheet ATA6621.PDF ] | |
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