U9280M-H View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

U9280M-H

Microcontroller with Transponder Interface

Atmel Corporation 

For the storage of data such as key codes, identifiers and configuration bits, a 512-bit EEPROM

is available on the chip. It can be read and written to by the microcontroller via a TWI-compatible

two-wire serial interface. The serial interface, the EEPROM and the microcontroller are supplied

with the voltage at the VDD pin. That means the microcontroller can read and write to the

EEPROM if the supply voltage is in the operating range.

The U3280M contains additional operating modes to support a wide range of applications.

These modes can be controlled via the serial interface. The power management can be

switched off by software to disable the automatic switching between battery and field. This sup-

ports applications with battery supply only.

There is an on-chip Bi-phase and Manchester modulator. It can be selected and controlled via

the serial interface with a special mode control byte. If this modulator is used the external con-

nection to the modulator input is not necessary.

3.3 Modulation

The transponder interface can modulate the magnetic field by a modulator to transmit data to a

base station. It modulates the coil voltage by varying the coil‘s load. The modulator can be con-

trolled via the MOD pin. A high level 1 increases the current into the coil inputs and damps the

coil voltage. A low level 0 decreases the current and increases the coil voltage. The modulator

generates a voltage stroke of about 2 Vpp at the coil. A high level at the MOD input makes the

maximum of the field energy available at VDD. During a reset a high level at the MOD input

causes the optimum conditions for starting the device and charging the capacitor at VDD after the

field is applied at the coil.

3.3.1

Digital Input to Control the Damping Stage (MOD)

Mod = 0: coil undamped

VCOIL_peak = VDD × 2 + VCMS = VCU

Mod = 1: coil damped

VCOIL_peak = VDD × 2 = VCD

VCMS = VCID: modulation voltage stroke at coil inputs

Note: If the automatic power management is disabled the internal front end VDD is limited at VDDC. In this

case the value VDDC must be used in the formula above.

3.4 Field Clock

The field clock extractor of the interface makes the field clock available for the microcontroller. It

can be used to supply timer inputs to synchronize modulation and demodulation with the field

clock.

6 U9280M-H

4591B–RFID–09/05

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