ata5277-pcq ATMEL Corporation, ata5277-pcq Datasheet - Page 4

• Manufacturer Part Number: ata5277-pcq
• Description: Stand-alone Antenna Driver
• Manufacturer: ATMEL Corporation

Functional Description
General Description
Operation Modes
Standby and Wake-up
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ATA5277 [Preliminary]
The IC contains a half-bridge coil driver stage with a special driver voltage regulator and
control logic with diagnosis circuitry. Further it contains a one-wire bi-directional micro-
controller interface for the carrier modulation and the mode selection. An integrated
oscillator for ceramic resonators generates the clock signal for the control logic. Addi-
tionally, the IC contains two connectors for switches to wake-up the IC.
The IC generates an electromagnetic LF field in combination with an LC antenna cir-
cuitry. The carrier frequency for the antenna is generated by the oscillator and prescaler
logic.
The LF field can be modulated to transmit data to a suitable receiver. There are two
modulation modes available, Amplitude Shift Keying (ASK) and 180° Phase Shift Keying
(PSK). A microcontroller or another control unit must be used to control the transmitter
via the bi-directional single-wire interface.
A boost converter power supply is used to supply the driver half-bridge and the antenna
with a high voltage and a regulated current even if the battery voltage is low. The
antenna current is programmable in 16 steps to support a transmission with various field
strengths.
The driver circuitry is Short Circuit (SC) protected and the driver logic contains diagnosis
functions for short circuit and open wire detection at the antenna outputs.
Three different operation modes are defined:
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After power-on reset, the ATA5277 is in standby mode. To achieve minimum power con-
sumption, only the internal 5-V supply, the DIO-line interface and the door switch inputs
are active. The IC can be activated either by the external control unit via the serial inter-
face or by one of the switch inputs. A low signal at the DIO-line or at the switch inputs
(SW1, SW2) powers up the IC. If this is done at a switch input, a low signal is generated
on the DIO-line which can be used as a wake-up signal for the connected
microcontroller.
In command mode, the IC can be configured and diagnostics can be run. This mode is
always activated after wake-up from standby mode and after leaving modulation mode.
The communication is based on a one-wire serial interface (DIO-line) with the con-
nected microcontroller being the master and ATA5277 being the slave. In this mode, the
antenna driver stage is disabled, except if the automatic field generation after wake-up
is selected.
In modulation mode, the antenna driver stage is activated (if enabled) and the data
applied to the DIO-line modulates the LF field (in ASK or PSK). This mode is activated
after the command mode and remains active as long as data is applied to the DIO-line
(i.e., until a timeout has occured). After that, the IC falls back to command mode.
There are two different wake-up modes. In the default mode the antenna driver stage
remains off after wake-up. The second mode can be programmed by a control com-
mand. Here, also the driver output stage is enabled. The IC generates the carrier signal
for the antenna immediately.
Standby
Command mode
Modulation mode
4669B–RKE–10/03