ATA6621.pdf 데이터시트 (총 26 페이지) - 파일 다운로드 ATA6621 데이타시트 다운로드

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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

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Figure 1-1. Block Diagram
9
RXD
VCC
Receiver
Normal
Mode
20
VS
4
WAKE
11
TXD
EN
GND
1
5
17
TEMP
16
GND
VS
Filter
7
LIN
VCC
TXD
Time-out
Timer
Debounce
Time
VCC
Wake-up Bus Timer
Slew Rate Control
Short Circuit and
Overtemperature
Protection
Control Unit
Standby Mode
Normal Mode
5V ± 2%/50 mA
Silent Mode
5V ± 7%/50 mA
Undervoltage
Reset
19
VCC
18
PVCC
12
NRES
Internal Testing
Unit
15 14
MODE TM
OUT
Watchdog
23
PTRIG NTRIG
VCC
Adjustable
Watchdog
Oscillator
13
WD_OSC
2 ATA6621
4887B–AUTO–01/06

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2. Pin Configuration
Figure 2-1. Pinning QFN20
20 19 18 17 16
EN
PTRIG
NTRIG
WAKE
GND
1
2
3
4
5
ATA6621
MLP 5 mm × 5 mm
0.65 mm pitch
20 lead
15 MODE
14 TM
13 WD_OSC
12 NRES
11 TXD
6 7 8 9 10
ATA6621
Table 2-1.
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Pin Description
Symbol Function
EN Enables the device into Normal Mode
PTRIG High-level watchdog trigger input from microcontroller; if not needed, leave open or connect to GND
NTRIG Low-level watchdog trigger input from microcontroller; if not needed, leave open or connect to VCC
WAKE High-voltage input for local wake-up request; if not needed, connect to VS
GND
System ground
NC Not connected
LIN LIN bus line input/output
NC Not connected
RXD
Receive data output
NC Not connected
TXD
Transmit data input; active low output (strong pull down) after a local wake-up request
NRES Output undervoltage and watchdog reset
WD_OSC Watchdog oscillator
TM For factory testing only (tie to ground)
MODE For factory testing only (tie to ground)
GND
Additional ground
TEMP Chip temperature output pin
PVCC 5V regulator sense input pin
VCC
5V regulator output/driver pin
VS Battery supply
Backside Heat slug is connected to GND (pin 5)
4887B–AUTO–01/06
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3. Functional Description
3.1 Supply Pin (VS)
The LIN operating voltage is VS = 5V to 18V. An undervoltage detection is implemented to dis-
able transmission if VS falls below 5V in order to avoid false bus messages. After switching on
VS, the IC starts with the Pre Normal Mode and the voltage regulator is switched on (that is,
5V/50 mA output capability).
The supply current in Sleep Mode is typically 10 µA, and 40 µA in Silent Mode.
3.2 Ground Pin (GND)
The IC is neutral on the LIN pin in case of GND disconnection; it can handle a ground shift up to
3V for supply voltage at the VS pin above 9V.
3.3 Voltage Regulator Output Pin (VCC)
The internal 5V voltage regulator is capable of driving loads with up to 50 mA of current con-
sumption; it is able to supply the microcontroller and other ICs on the PCB. It is protected
against overloads by means of current limitation and overtemperature shutdown. Furthermore,
the output voltage is monitored and will cause a reset signal at the NRES output pin if the output
voltage drops below a defined threshold Vthun. To boost up the maximum load current, an exter-
nal NPN transistor may be used with its base connected to the VCC pin and its emitter
connected to PVCC.
3.4 Voltage Regulator Sense Pin (PVCC)
This is the sense input pin of the 5V voltage regulator. For normal applications (that is, when
only using the internal output transistor), this pin is connected to the VCC pin. If an external
boosting transistor is used, the PVCC pin must be connected to the output of this transistor, its
emitter terminal.
3.5 Bus Pin (LIN)
A low side driver with internal current limitation and thermal shutdown, and an internal pull-up
resistor in compliance with LIN specification 2.0 is implemented. This is a self-adapting current
limitation; that is, during current limitation, as the chip temperature increases, the current
decreases. The allowed voltage range is between –40V and +60V. Reverse currents from the
LIN bus to VS are suppressed, even in case of ground shifts or battery disconnection. LIN
receiver thresholds are compatible to the LIN protocol specification. The fall time from recessive
bus state to dominant, and the rise time from dominant bus state to recessive are slope
controlled.
3.6 Input Pin (TXD)
This pin is the microcontroller interface to control the state of the LIN output. TXD must be pulled
to ground in order to have the LIN bus low. If TXD is high, the LIN output transistor is turned off
and the bus is in the recessive state, pulled up by the internal resistor.
4 ATA6621
4887B–AUTO–01/06

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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 kto 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
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