ATA5279N Datasheet, PDF (4/38 Pages) ATMEL Corporation – Antenna Driver for Multiple Antennas

3. Functional Description
3.1 Operation Modes
ATA5279N features five operation modes. They are:
• Power-down mode (reset state)
• Idle mode
• Operating mode
• Shutdown mode
• Diagnosis mode
Power-down mode is active after supply voltages have been applied to the chip. No internal cir-
cuitry is active in this mode and as such power consumption is minimal. If no operation of the
chip is demanded, it should be kept in this state. To enter power-down mode, a negative pulse
on the NRES pin for at least t_NRES,min is required.
After wake-up from power-down mode by a logic high signal at the S_CS pin, the chip is in idle
mode. That is, the oscillator is running and the control logic waits for commands coming from the
serial interface. Furthermore, the selected output driver stage is ready for operation (the voltage
on the corresponding output pin AxP is approximately half the battery supply voltage). The cur-
rent consumption of the chip is now mainly defined by the cross current through the active driver
stage (please refer also to Section 3.2 “Coil Driver Stage” on page 5).
When processing coil driving commands, the chip is in operation mode. From the interface point
of view, there is no difference from the idle mode; however, current consumption is now higher
as the output driver stages are operating and, depending on the selected output current, the
DC-DC converter is also operating.
If a connection failure (short circuit on any of the coil connection lines) is detected, the
ATA5279N enters the shutdown mode to protect itself from damage. In this mode, the interface
operates in idle mode but with all power stages shutdown and no LF transmission command pro-
cessing. This mode should be exited using the Reset Fault Status command (see below),
however, it can also be exited by resetting the chip.
In diagnosis mode, the output driver stages are also disabled. In their place, high-ohmic current
sources are activated that can be programmed via the serial interface in order to check the coil
connection lines for failures. This mode can be exited by an appropriate SPI command or by
resetting the chip.
4 ATA5279N [Preliminary]
9125F–RKE–09/09