Rainbow Electronics ATA6662 User Manual

Features

• Operating Range from 5V to 27V

• Baud Rate up to 20 Kbaud

• Improved Slew Rate Control According to LIN Specification 2.0 and SAEJ2602-2

• Fully Compatible with 3.3V and 5V Devices

• Dominant Time-out Function at Transmit Data (TXD)

• Normal and Sleep Mode

• Wake-up Capability via LIN Bus (90 µs Dominant)

• External Wake-up via WAKE Pin (35 µs Low Level)

• Control of External Voltage Regulator via INH Pin

• Very Low Standby Current During Sleep Mode (10 µA)

• Wake-up Source Recognition

• Bus Pin Short-circuit Protected versus GND and Battery

• LIN Input Current Typically 5 µA if V

Is Disconnected

BAT

• Overtemperature Protection

• High EMC Level

• Interference and Damage Protection According to ISO/CD 7637

• ESD HBM 6 kV at LIN Bus Pin and Supply VS Pin

1. Description

The ATA6662 is a fully integrated LIN transceiver complying with the LIN specification 2.0 and SAEJ2602-2. It interfaces the LIN protocol handler and the physical layer. The device is designed to handle the low-speed data communication in vehicles, for example, in convenience electronics. Improved slope control at the LIN bus ensures secure data communication up to 20 Kbaud with an RC oscillator for protocol handling. Sleep mode guarantees minimal current consumption. The ATA6662 has advanced EMI and ESD performance.

LIN Transceiver

ATA6662

Preliminary

Figure 1-1. Block Diagram

RXD

TXD

WAKE

TXD

time-out

timer

Wake-up

timer

Receiver

Filter

Wake-up bus timer

Slew rate control

Control unit

Standby mode

Short circuit and overtemperature protection

INH

LIN

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2. Pin Configuration

Figure 2-1. Pinning SO8

INH

RXD

WAKE

TXD

3 4

Table 2-1. Pin Description

Pin Symbol Function

1 RXD Receive data output (open drain) 2 EN Enables normal mode; when the input is open or low, the device is in sleep mode 3 WAKE High voltage input for local wake-up request 4 TXD Transmit data input; active low output (strong pull-down) after a local wake-up request 5 GND Ground, heat sink 6 LIN LIN bus line input/output 7 VS Battery supply

8INH

Battery-related inhibit output for controlling an external voltage regulator; active high after a wake-up request

LIN

GND

ATA6662 [Preliminary]

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3. Functional Description

3.1 Supply Pin (VS)

Undervoltage detection is implemented to disable transmission if VS falls to a value below 5V in order to avoid false bus messages. After switching on V and INHIBIT is switched on. The supply current in sleep mode is typically 10 µA.

3.2 Ground Pin (GND)

The ATA6662 is neutral on the LIN pin in the case of a GND disconnection. It is able to handle a ground shift up to 11.5% of V

3.3 Bus Pin (LIN)

A low-side driver with internal current limitation and thermal shutdown and an internal pull-up resistor are implemented as specified for LIN 2.0. The voltage range is from –27V to +40V. This pin exhibits no reverse current from the LIN bus to V disconnection. The LIN receiver thresholds are compatible to the LIN protocol specification.The fall time (from recessive to dominant) and the rise time (from dominant to recessive) are slope controlled. The output has a self-adapting short circuit limitation; that is, during current limitation, as the chip temperature increases, the current is reduced.

ATA6662 [Preliminary]

, the IC switches to pre-normal mode

, even in the case of a GND shift or V

Batt

3.4 Input Pin (TXD)

This pin is the microcontroller interface to control the state of the LIN output. TXD is low to bring LIN low. If TXD is high, the LIN output transistor is turned off. Then, the bus is in recessive mode via the internal pull-up resistor. The TXD pin is compatible to both a 3.3V or 5V supply.

3.5 TXD Dominant Time-out Function

The TXD input has an internal pull-down resistor. An internal timer prevents the bus line from being driven permanently in dominant state. If TXD is forced low longer than t LIN will be switched off (recessive mode). To reset this mode, switch TXD to high (>10 µs) before switching LIN to dominant again.

3.6 Output Pin (RXD)

This pin reports to the microcontroller the state of the LIN bus. LIN high (recessive) is reported by a high level at RXD, LIN low (dominant) is reported by a low voltage at RXD. The output is an open drain, therefore, it is compatible to a 3.3V or 5V power supply. The AC characteristics are defined with a pull-up resistor of 5 kΩ to 5V and a load capacitor of 20 pF. The output is short-current protected. In unpowered mode (V a Zener diode is integrated, with V

=6.1V.

> 6 ms, the pin

dom

= 0V), RXD is switched off. For ESD protection

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3.7 Enable Input Pin (EN)

This pin controls the operation mode of the interface. If EN = 1, the interface is in normal mode, with the transmission path from TXD to LIN and from LIN to Rx both active. A falling edge on EN while TXD is already set to high, the device is switched to sleep mode and no transmission is possible. In sleep mode, the LIN bus pin is connected to V The device can transmit only after being woken up (see Section 3.8, “Inhibit Output Pin (INH)” ).

During sleep mode the device is still supplied from the battery voltage. The supply current is typically 10 µA. The pin EN provides a pull-down resistor in order to force the transceiver into sleep mode in case the pin is disconnected.

3.8 Inhibit Output Pin (INH)

This pin is used to control an external switchable voltage regulator having a wake-up input. The inhibit pin provides an internal switch towards pin V 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.

with a weak pull-up current source.

. If the device is in normal mode, the inhibit

A wake-up event on the LIN bus or at pin WAKE will switch the INH pin to the V system power-up (V R

of the high-side output is < 1 kΩ.

DSon

3.9 Wake-up Input Pin (WAKE)

This pin is a high-voltage input used to wake the device up from sleep mode. It is usually connected to an external switch in the application to generate a local wake-up. If you do not need a local wake-up in your application, connect pin WAKE directly to pin VS. A pull-up current source with typically –10 µA is implemented. The voltage threshold for a wake-up signal is 3V below the VS voltage with an output current of typically –3 µA.

Wake-up events from sleep mode:

•LIN bus

•EN pin

• WAKE pin

Figure 3-1 on page 6, Figure 3-2 on page 7 and Figure 3-3 on page 7 show details of wake-up

operations.

level. After a

rises from zero), the pin INH switches automatically to the VS level. The

ATA6662 [Preliminary]

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3.10 Operation Modes

1. Normal mode

2. Sleep mode

3. Pre-normal mode

ATA6662 [Preliminary]

This is the normal transmitting and receiving mode. All features are available.

In this mode the transmission path is disabled and the device is in low power mode. Supply current from V WAKE will be detected and will switch the device to pre-normal mode. If EN then switches to high, normal mode is activated. Input debounce timers at pin WAKE (T

WAKE

), LIN (T

BUS

motive transients or EMI. In sleep mode the INH pin is left floating. The internal termination between pin LIN and pin V case pin LIN is short-circuited to GND. Only a weak pull-up current (typical 10 µA) between pin LIN and pin V from the actual level on pin LIN or WAKE, guaranteeing that the lowest power consumption is achievable even in the case of a continuous dominant level on pin LIN or a continuous LOW on pin WAKE.

At system power-up, the device automatically switches to pre-normal mode. It switches the INH pin to a high state, to the V then confirm the normal mode by setting the EN pin to high.

is typically 10 µA. A wake-up signal from the LIN bus or via pin

Batt

) and EN (T

is present. The sleep mode can be activated independently

sleep,Tnom

) prevent unwanted wake-up events due to auto-

is disabled to minimize the power dissipation in

level. The microcontroller of the application will

3.11 Remote Wake-up via Dominant Bus State

A voltage less than the LIN pre-wake detection V transceiver.

A falling edge at pin LIN, followed by a dominant bus level V period (T

) and a rising edge at pin LIN results in a remote wake-up request.

BUS

The device switches to pre-normal mode. Pin INH is activated (switches to V termination resistor is switched on. The remote wake-up request is indicated by a low level at pin RXD to interrupt the microcontroller (see Figure 3-2 on page 7).

3.12 Local Wake-up via Pin WAKE

A falling edge at pin WAKE, followed by a low level maintained for a certain time period (T results in a local wake-up request. The wake-up time (T ing to ISO7637, creates a wake-up. The device switches to pre-normal mode. Pin INH is activated (switches to V request is indicated by a low level at pin RXD to interrupt the microcontroller and a strong pull-down at pin TXD (see Figure 3-3 on page 7). The voltage threshold for a wake-up signal is 3V below the VS voltage with an output current of typical –3 µA. Even in the case of a continuous low at pin WAKE it is possible to switch the IC into sleep mode via a low at pin EN. The IC will stay in sleep mode for an unlimited time. To generate a new wake up at pin WAKE it needs first a high signal > 6 µs before a negative edge starts the wake-up filtering time again.

) and the internal termination resistor is switched on. The local wake-up

at pin LIN activates the internal LIN

LINL

maintained for a certain time

BUSdom

) and the internal

) ensures that no transient, accord-

WAKE

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