ATMEL U3280M

Features
•
•
•
•
•
•
•
•
•
•
•
Contactless Power Supply and Communication Interface
Up to 10 kbaud Data Rate (R/O)
Power Management for Contactless and Battery Power Supply
Frequency Range 100 kHz to 150 kHz
32 x 16-bit EEPROM
Two-wire Serial Interface
Shift Register Supported Bi-phase and Manchester Modulator Stage
Reset I/O Line
Field Clock Extractor
Field and Gap Detection Output for Wake-up and Data Reception
Field Modulator with Energy-saving Damping Stage
Applications
• Main Areas
– Access Control
– Telemetry
– Wireless Sensors
• Examples:
– Wireless Passive Access and Active Alarm Control for Protection of Valuables
– Contactless Position Sensors for Alignments of Machines
– Contactless Status Verification and/or Data Readout from Sensors
Transponder
Interface for
Microcontroller
U3280M
Description
The U3280M is a transponder interface for use in contactless ID systems, remote control systems, tag and sensor applications. It supplies the microcontroller with power
from an RF field via an LC-resonant circuit and it enables contactless bi-directional
data communication via this RF field. It includes power management that handles
switching between the magnetic field and a battery power supply. To store permanent
data like an identifier code and configuration data, the U3280M includes a 512-bit
EEPROM with a serial interface.
Figure 1. Block Diagram
U3280M Transponder Interface
Energy
VField
regulator
Sensors, keys, displays, actuators
NRST
Damping
stage
VDD
Coil 1
512-bit
EEPROM
memory
Rectifier
Coil 2
Data
VBatt
Power
management
Low power
microcontroller
SDA
Field/gap
detect
Serial
interface
Clock
extractor
Bi-phase
modulator
FC
>
_1
NGAP
MOD
SCL
VSS
Transmit data
Receive data/field detected
Field clock
Rev. 4688B–RFID–12/04
Pin Configuration
Figure 2. Pinning
VBatt
VDD
SCL
NRST
SDA
VSS
NC
FC
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
Coil 2
Coil 1
NC
NC
NC
NC
NGAP
MOD
Pin Description
2
Pin
Symbol
Function
1
VBatt
Power supply voltage input to connect a battery
2
VDD
Power supply voltage for the microcontroller and EEPROM. At this pin a buffer capacitor (0.5 to 10 µF)
must be connected to buffer the voltage during field supply and to block the VDD of the microcontroller.
3
SCL
Serial clock line
4
NRST
5
SDA
Serial data line
6
VSS
Circuit ground
7
NC
Not connected
8
FC
Field clock output of the front-end clock extractor
9
MOD
Modulation input
10
NGAP
Gap and field detect output
11
NC
Not connected
12
NC
Not connected
13
NC
Not connected
Reset line bi-directional
14
NC
15
Coil 1
Coil input 1. Use pin to connect a resonant circuitry for communication and field supply
Not connected
16
Coil 2
Coil input 2. Use pin to connect a resonant circuitry for communication and field supply
U3280M
4688B–RFID–12/04
U3280M
Functional Description
Transponder Interface
The U3280M is a transponder interface IC that can operate microcontrollers using wireless technology and battery independently. Wireless data communication and the power
supply are handled via an electromagnetic field and the coil antenna of the transponder
interface. The U3280M consists of a rectifier stage for the antenna, power management
to handle field and battery power supplies, a damping modulator, and a field-gap detection stage for contactless data communication. Furthermore, a field clock extraction and
an EEPROM are on-chip.
The internal rectifier stage rectifies the AC from the LC-resonant circuit at the coil inputs
and supplies the U3280M device and an additional microcontroller device with power. It
is also possible to supply the device via the VBatt input with DC from a battery. The
power management handles switching between battery supply (VBatt pin) and field supply automatically. It switches to field supply if a field is applied at the coil, and it switches
back to battery if the field is removed. The voltage from the coil or the VBatt pin is output
at the VDD pin to supply the microcontroller or any other suited device. At the VDD pin a
capacitor must be connected to smooth and buffer the supply voltage. This capacitor is
also necessary to buffer the supply voltage during communication (damping and gaps in
the field).
For communication, the chip contains a damping stage and gap-detect circuitry. By
means of the damping stage the coil voltage can be modulated to transmit data via the
field. It can be controlled with the modulator input (MOD pin) via the microcontroller. The
gap-detection circuitry detects gaps in the field and outputs the gap/field signal at the
gap-detect output (Pin NGAP).
To store data like keycodes, identifiers and configuration bits, a 512-bit EEPROM is
available on-chip. It can be read and written by the microcontroller via a 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 the EEPROM if the
supply voltage at VDD is in the operating range of the IC.
The U3280M has built-in operating modes to support a wide range of applications.
These modes can be activated via the serial interface with special mode control bytes.
To support applications with battery supply only, power management can be switched
off by software to disable the automatic switching to field supply.
An on-chip Bi-phase and Manchester modulator can be activated and controlled by the
serial interface. If this modulator is used, it modulates the serial data stream at the serial
inputs SDA and SCL into a Bi-phase or Manchester-coded signal for the damping stage.
Modulation
The transponder interface can modulate the magnetic field by its damping stage to
transmit data to a base station. It modulates the coil voltage by varying the coil’s load.
The modulator can be controlled via the MOD pin. A high level (“1”) increases the current into the coil 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 pin makes the maximum of the field energy available at
VDD. During reset mode, a high level at the MOD pin causes optimum conditions for
starting the device and charging the capacitor at VDD after the field has been applied at
the coil.
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4688B–RFID–12/04
Digital Input to Control the
Damping Stage (MOD)
MOD = 0: coil not damped
V coil-peak = V DD ×
2 + V CMS = V CU
MOD = 1: coil damped
V coil-peak = V DD ×
2 = V CD
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 above formula.
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.
Gap Detect
The transponder interface can also receive data. The base station modulates the data
with short gaps in the field. The gap-detection circuit detects these gaps in the magnetic
field and outputs the NGAP/field signal at the NGAP pin. A high level indicates that a
field is applied at the coil and a low level indicates a gap or that the field is off. The
microcontroller must demodulate the incoming data stream at one of its inputs.
U3280M Signals and Timing
Figure 3. Modulation
MOD
VCU
VCMS
VCD
Coil inputs
Figure 4. GAP and Modulation Timing
Gap detection and battery to field switching
t FGAP1
t FGAP0
V
FDON
V FDOFF
Coil inputs
1. edge used as wakeup signal
NGAP
Field clock FC
Power
management
Battery supply
t BFS
4
Battery
supply
Coil supply if automatically power management is enabled
tFBS
U3280M
4688B–RFID–12/04
U3280M
Digital Output of the
Gap-detection Stage
(NGAP)
NGAP = 0: gap detected/no field
Vcoil-peak = VFDoff
NGAP = 1: field detected
Vcoil-peak = VFDon
Wake-up Signal
If a field is applied at the coil of the transponder interface, the microcontroller can be
woken up with the wake-up signal at the NGAP pin. For that purpose, the NGAP pin
must be connected to an interrupt input of the microcontroller. A high level at the NGAP
output indicates an applied field and can be used as a wake-up signal for the microcontroller via an interrupt. The wake-up signal is generated if power management switches
to field supply. The field-detection stage of the power management has lowpass characteristics to avoid generating wake-up signals and unnecessary switching between
battery and field supply in case of interferences at the coil inputs.
Power Supply
The U3280M has a power management that handles two power supply sources. Normally, the IC is supplied by a battery at the VBatt pin. If a magnetic field is applied at the
LC-resonant circuit of the device, the field detection circuit switches automatically from
VBatt to field supply.
Note:
No amplifier is used in the gap-detection stage. A digital Schmitt trigger evaluates the
rectified and smoothed coil voltage.
The VDD pin is used to connect a capacitor to smooth the voltage from the rectifier and
to buffer the power while the field is modulated by gaps and damping. The EEPROM
and the connected controller always operate with the voltage at the VDD pin.
Note:
Automatic Power
Management
During field supply the maximum energy from the field is used if a high level is applied at
the MOD input.
There are different conditions that cause a switch from the battery to field and back from
field to the battery.
The power management switches from battery to field if the rectified voltage (Vcoil) from
the coil inputs becomes higher than the field-on-detection voltage (VFDon), even if no battery voltage is available (0 < VBatt < 1.8 V). It switches back to battery if the coil voltage
becomes lower than the field-off-detection voltage (VFDoff).
The field detection stage of the power management has low pass characteristics to suppress noise. An applied field needs a time delay tBFS (battery-to-field switch delay) to
change the power supply. If the field is removed from the coil, the power management
will generate a reset that can be connected to the microcontroller.
Figure 5. Switch Conditions for Power Management
VCoil > VFDon for t > tBFS
Battery
supply
(VBatt)
Field
supply
VCoil < VFDon for t > tBFS
Note:
The rectified supply voltage from the coil is limited to VDDC (2.9 V). During field supply,
the battery is switched off and VDD changes to VDDC.
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4688B–RFID–12/04
Controlling Power
Management via the Serial
Interface
The automatic mode of the power management can be switched off and on by a command from the microcontroller. If the automatic mode is switched off, the IC is always
supplied by the battery up to the next power-on reset or to a switch-on command. The
power management’s on and off command must be transferred via the serial interface.
If the power management is switched off and the device is supplied from the battery, it
can communicate via the field without loading the field. This mode can be used to realize applications with battery supply if the field is too weak to supply the IC with power.
Buffer Capacitor CB
The buffer capacitor connected at VDD is used to buffer the supply voltage for the microcontroller and the EEPROM during field supply. It smoothes the rectified AC from the
coil and buffers the supply voltage during modulation and gaps in the field. The size of
this capacitor depends on the application. It must be of a dimension so that during modulation and gaps the ripple on the supply voltage is in the range of 100 mV to 300 mV.
During gaps and damping the capacitor is used to supply the device, which means the
size of the capacitor depends on the length of the gaps and damping cycles.
Table 1. Example for a 350 µA Supply Current, 200 mV Ripple at VDD
No Field Supply During
Serial Interface
Necessary CB
250 µs
470 nF
500 µs
1000 nF
The transponder interface has a serial interface to the microcontroller for read and write
access to the EEPROM. In a special mode, the serial interface can also be used to control the Bi-phase/Manchester modulator or the power management of the U3280M.
The serial interface of the U3280M device must be controlled by a master device (normally the microcontroller) which generates the serial clock and controls the access via
the SCL and SDA lines. SCL is used to clock the data in and out of the device. SDA is a
bi-directional line and used to transfer data into and out of the device. The following protocol is used for the data transfers.
Serial Protocol
6
•
Data states on the SDA line change only when SCL is low.
•
Changes in the SDA line while SCL is high will be interpreted as a START or STOP
condition.
•
A STOP condition is defined as a high-to-low transition on the SDA line while the
SCL line is high.
•
Each data transfer must be initialized with a START condition and terminated with a
STOP condition. The START condition awakens the device from standby mode, and
the STOP condition returns the device to standby mode.
•
A receiving device generates an acknowledge (A) after the reception of each byte.
For that purpose the master device must generate an extra clock pulse. If the
reception was successful, the receiving master or slave device pulls down the SDA
line during that clock cycle. If an acknowledge has not been detected (N) by the
interface in transmit mode, it will terminate further data transmissions and switch to
receive mode. A master device must finish its read operation by a not acknowledge
and then issue a STOP condition to switch the device to a known state.
U3280M
4688B–RFID–12/04
U3280M
Figure 6. Serial Protocol
SCL
SDA
Stand- START
by condition
Data/
Data
change acknowledge
valid
Data
valid
STOP Standcondition by
Control Byte Format
EEPROM address
START
A4
A3
A2
A1
A0
Mode control
bits
Read/
NWrite
C1
R/NW
C0
Ackn
The control byte follows the START condition and consists of the 5-bit row address, 2
mode control bits and the read/not-write bit.
Data Transfer Sequence
START
Control byte
Ackn
Data byte
Ackn
Data byte
Ackn
STOP
•
After the STOP condition and before the START condition the device is in standby
mode and the SDA line is switched to an input with the pull-up resistor.
•
The START condition follows a control byte that determines the following operation.
Bit 0 of the control byte is used to control the following transfer direction. A “0”
defines a write access and a “1” defines a read access.
EEPROM
The EEPROM has a size of 512 bits and is organized as a 32 × 16-bit matrix. To read
and write data to and from the EEPROM, the serial interface must be used. The interface supports one and two-byte write access and one to n-byte read access to the
EEPROM.
EEPROM Operating
Modes
The operating modes of the EEPROM are defined by the control byte. The control byte
contains the row address, the mode control bits and the read/not-write bit that is used to
control the direction of the following transfer. A “0” defines the write access and a “1”
defines a read access. The five address bits select one of the 32 rows of EEPROM
memory to be accessed. For complete access the complete 16-bit word of the selected
row is loaded into a buffer. The buffer must be read or overwritten via the serial interface. The two mode control bits C1 and C2 define in which order the access to the buffer
is performed: high byte – low byte or low byte – high byte. The EEPROM also supports
auto-increment and auto-decrement read operations. After sending the START address
with the corresponding mode, consecutive memory cells can be read row by row without
transmission of the row addresses.
Two special control bytes allow the initialization of the complete EEPROM with “0” or
with “1”.
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4688B–RFID–12/04
Write Operations
The EEPROM allows for 8-bit and 16-bit write operations. A write access starts with the
START condition followed by writing a write control byte and one or two data bytes from
the master. It is completed with the STOP condition from the master after the acknowledge cycle.
When the EEPROM receives the control byte, it loads the addressed memory cell into a
16-bit read/write buffer. The following data bytes overwrite the buffer. The internal
EEPROM programming cycle is started by a STOP condition after the first or second
data byte. During the programming cycle, the addressed EEPROM cells are cleared and
the contents of the buffer is written back to the EEPROM cells. The complete erasewrite cycle takes about 10 ms.
Acknowledge Polling
If the EEPROM is busy with an internal write cycle, all inputs are disabled and the
EEPROM will not acknowledge until the write cycle is finished. This can be used to
determine when the write cycle is complete. The master must perform acknowledge
polling by sending a START condition followed by the control byte. If the device is still
busy with the write cycle, it will not return an acknowledge and the master has to generate a STOP condition or perform further acknowledge polling sequences.
If the cycle is complete, the device returns an acknowledge and the master can proceed
with the next read or write cycle.
Write One Data Byte
START
Control byte
A Data byte 1
START
Control byte
A
START
Control byte
A STOP
A STOP
Write Two Data Bytes
Data byte 1
A Data byte 2
A STOP
Write Control Byte Only
A →acknowledge
Write Control Bytes
Write Low Byte First
MSB
A4
LSB
A3
A2
A1
A0
Row address
Byte Order
LB(R)
C1
C0
R/NW
0
1
0
HB(R)
Write High Byte First
MSB
A4
LSB
A3
A2
A1
Row address
Byte Order
HB(R)
A0
C1
C0
R/NW
1
0
0
LB(R)
HB: high byte; LB: low byte; R: row address
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U3280M
4688B–RFID–12/04
U3280M
Read Operations
The EEPROM allows byte-, word- and current address read operations. The read operations are initiated in the same way as write operations. Each read access is initiated by
sending the START condition followed by the control byte which contains the address
and the read mode. When the device has received a read command, it returns an
acknowledge, loads the addressed word into the read/write buffer and sends the
selected data byte to the master. The master has to acknowledge the received byte to
proceed with the read operation. If two bytes are read out from the buffer, the device
automatically increments or decrements the word address and loads the buffer with the
next word. The read mode bit determines if the low or high byte is read first from the
buffer and if the word address is incremented or decremented for the next read access.
When the memory address limit has been reached, the data word address will “roll over”
and the sequential read will continue. The master can terminate the read operation after
every byte by not responding with an acknowledge (N) and by issuing a STOP
condition.
Read One Data Byte
START
Control byte
A Data byte 1
N STOP
START
Control byte
A Data byte 1
A Data byte 2
Read Two Data Bytes
N STOP
Read n Data Bytes
START
Control byte
A
Data byte 1
A Data byte 2 A
------
Data byte n N STOP
A →acknowledge, N →no acknowledge
Read Control Bytes
Read Low Byte First, Address Increment
MSB
A4
LSB
A3
A2
A1
A0
C1
C0
R/NW
0
1
1
Row address
Byte Order
LB(R)
HB(R)
LB(R+1)
HB(R+1)
----
LB(R+n)
HB(R+n)
Read High Byte First, Address Decrement
MSB
A4
LSB
A3
A2
A1
A0
Row address
C1
C0
R/NW
1
0
1
Byte Order
HB(R)
LB(R)
HB(R-1)
LB(R-1)
----
HB(R-n)
LB(R-n)
HB: high byte; LB: low byte; R: row address
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4688B–RFID–12/04
Initialization after a Reset
Condition
The EEPROM with the serial interface has reset circuitry on-chip. In systems with microcontrollers that have their own reset circuitry for power-on reset, watchdog reset or
brown-out reset, it may be necessary to bring the U3280M into a known state independently of the internal reset. This is performed by reading one byte without
acknowledging and then generating a STOP condition.
Special Modes
Table 2. Control Byte Description
Control Byte
Description
1100x111b
Bi-phase modulation
1101x111b
Manchester modulation
11xx0111b
Switch power management off →disables switching from battery to
field supply
11xx1111b
Switch power management on →enables automatic switching between
battery and field supply
xxxxx110b
Reserved
Data Transfer Sequence for Bi-phase and Manchester Modulation
START
Control byte
Ackn
Bit 1
Bit 2
Bit 3
-----------
Bit n
STOP
By using special control bytes, the serial interface can control the modulator stage or the
power management. The EEPROM access and the serial interface are disabled in these
modes until the next STOP condition. If no START or STOP condition is generated, the
SCL and SDA lines can be used for the modulator stage. SCL is used for the modulator
clock and SDA is used for the data. In this mode, the same conditions for clock and data
changing, as in normal mode, are valid. The SCL and SDA lines can be used for continuous bit transfers, an acknowledge cycle after 8 bits must not be generated.
Note:
Power-on Reset, NRST
After a reset of the microcontroller it is not assured that the transponder interface has
been reset as well. It could still be in a receive or transmit cycle. To switch the device’s
serial interface to a known state, the microcontroller should read one byte from the
device without acknowledge and then generate a STOP condition.
The U3280M transponder front end starts working with the applied field. For the digital
circuits like the EEPROM serial interface and registers there is reset circuitry. A reset is
generated by a power-on condition at VDD, by switching back from field to battery supply
and if a low signal is applied at the NRST-pin.
The NRST-pin is a bi-directional pin and can also be used as a reset output to generate
a reset for the microcontroller if the circuit switches over from field to battery supply. This
sets the microcontroller in a well-defined state after the uncertain power supply condition during switching.
Antenna
For the transponder interface a coil must be used as an antenna. Air and ferrite cored
coils can be used. The achievable working distance (passive mode, not battery
assisted) depends on the minimum coupling factor of an application, the power consumption, and the size of the antennas of the IC and the base station. With a power
consumption of 150 µA, a minimum magnetic coupling factor below 0.5% is within
reach. For applications with a higher power consumption, the coupling factor must be
increased.
The Q-factor of the antenna coil should be in a range between 30 and 80 for read only
applications and below 40 for bi-directional read-write applications.
10
U3280M
4688B–RFID–12/04
U3280M
The antenna coil must be connected with a capacitor as a parallel LC resonant circuit to
the Coil 1 and Coil 2 pins of the IC. The resonance frequency f0 of the antenna circuit
should be in the range of 100 kHz to 150 kHz.
The correct LC combination can be calculated with the following formula:
1
L A = -----------------------------------------------2
CA × ( 2 × π × f0 )
Figure 7. Antenna Circuit Connection
Coil 1
LA
CA
Coil 2
Example: Antenna frequency: f0 = 125 kHz, capacitor: CA = 2.2 nF
1
L A = --------------------------------------------------------------------------- = 737 µH
2.2 nF × ( 2 × π × 125 kHz ) 2
Absolute Maximum Ratings
Voltages are given relative to VSS
Parameter
Symbol
Value
Supply voltage
Unit
VDD, VBatt
0 V to +7.0 V with reverse protection
V
Maximum current out of VSS pin
ISS
15
mA
Maximum current into VBatt pin
IBatt
15
mA
Input voltage (on any pin)
VIN
VSS -0.6 ≤VIN ≤VDD +0.6
V
IIK/IOK
±15
mA
±2
kV
Input/output clamp current (VSS > Vi/Vo > VDD)
Min. ESD protection (100 pF through 1.5 kΩ)
Operating temperature range
Tamb
-40 to +85
°C
Storage temperature range
TSTG
-40 to +125
°C
Soldering temperature (t ≤10 s)
TSD
260
°C
Note:
Stresses greater than those listed under absolute maximum ratings may cause permanent damage to the device. This is a
stress rating only and functional operation of the device at any condition beyond those indicated in the operational section of
these specification is not implied. Exposure to absolute maximum rating conditions for an extended period may affect device
reliability. All inputs and outputs are protected against high electrostatic voltages or electric fields. However, precautions to minimize build-up of electrostatic charges during handling are recommended. Reliability of operation is enhanced if unused inputs
are connected to an appropriate logic voltage level (for example, VDD).
Thermal Resistance
Parameter
Junction ambient
Symbol
Value
Unit
RthJA
180
K/W
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4688B–RFID–12/04
DC Characteristics
Supply voltage VDD = 1.8 V to 6.5 V, VSS = 0 V, Tamb = -40° C to 85° C unless otherwise specified
Parameters
Test Conditions
Pin
Symbol
Min.
VBatt
2.0
Typ.
Max.
Unit
6.5
V
Power Supply
Operating voltage at VBatt
Operating voltage at VDD during
battery supply
VDDB
VDD-limiter voltage during coil
supply
VDDC
Operating current during field
supply
VDD > 2.0 V
Sleep current
VBatt–
VSD
2.6
IFi
V
2.9
3.2
V
40
80
µA
0.4
µA
500
1200
µA
µA
300
350
µA
µA
2.9
V
ISl
EEPROM
Operating current during
erase/write cycle
VDD = 2.0 V
VDD = 6.5 V
IWR
IWR
Operating current during read
cycle
VDD = 2.0 V
VDD = 6.5 V
Peak current during 1/4 of read
cycle
IRdp
IRdp
400
Power Management
Field-on detection voltage
VDD > 1.8 V
VFDon
Field-off detection voltage
VDD > 1.8 V
VFDoff
Voltage drop at
power-supply switch
IS = 0.5 mA,
VBatt = 2 V
VSD
150
mV
Coil input current
ICI
20
mA
Input capacitance
CIN
30
VCMS
1.8
VIL
VIH
2.3
2.5
0.8
V
Coil Inputs: Coil 1 and Coil 2
Coil voltage stroke during
modulation
VCU > 5V
Icoil = 3 to 20 mA
pF
2.3
4.0
V
VIH
0.2 ×
VDD
V
0.8 ×
VDD
VDD
V
Pin MOD
Input LOW voltage
Input LOW voltage
Input leakage current
IIleakage
10
nA
Pin NGAP/FC
Output LOW current
VDD = 2.0 V
VOL = 0.2 × VDD
IOL
0.08
0.2
0.3
mA
Output HIGH current
VDD = 2.0 V
VOH = 0.8 × VDD
IOH
-0.06
-0.15
-0.25
mA
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U3280M
4688B–RFID–12/04
U3280M
DC Characteristics (Continued)
Supply voltage VDD = 1.8 V to 6.5 V, VSS = 0 V, Tamb = -40° C to 85° C unless otherwise specified
Parameters
Test Conditions
Pin
Symbol
Min.
Input LOW voltage
VIL
Input HIGH voltage
VIH
Typ.
Max.
Unit
VIH
0.3 ×
VDD
V
0.7 ×
VDD
VDD
V
Serial Interface I/O Pins SCL and SDA
Input leakage current
Output LOW current
Output HIGH current
IIleakage
VDD = 2.0 V
VOL = 0.2 VDD
VDD = 6.0 V
IOL
VDD = 2.0 V
VOH = 0.8 VDD
VDD = 6.0 V
IOH
10
nA
0.7
0.9
1.1
mA
2.8
3.5
4.2
mA
-0.5
-0.6
-0.7
mA
-1.8
-2.2
-2.6
mA
Typ.
Max.
Unit
100
kHz
AC Characteristics
Supply voltage VDD = 1.8 V to 6.5 V, VSS = 0 V, Tamb = -40° C to 85° C unless otherwise specified
Parameters
Test Conditions
Pin
Symbol
Min.
fSCL
0
Clock low time
tLOW
4.7
µs
Clock high time
tHIGH
4.0
µs
Serial Interface Timing
SCL clock frequency
SDA and SCL rise time
tR
1000
ns
SDA and SCL fall time
tF
300
ns
START condition setup time
tSUSTA
4.7
µs
START condition hold time
tHDSTA
4.0
µs
Data input setup time
tSUDAT
250
ns
Data input hold time
tHDDAT
0
ns
STOP condition setup time
tSUSTO
4.7
µs
tBUF
4.7
µs
Bus free time
Input filter time
tI
Data output hold time
tDH
300
fCOIL
100
100
ns
1000
ns
150
kHz
Coil Inputs
Coil frequency
125
Gap Detection
Delay field off to GAP = 0
VcoilGap < 0.7 VDC
TFGAP0
10
50
µs
Delay field on to GAP = 1
VcoilGap > 3 VDC
TFGAP1
1
50
µs
1000
µs
30
ms
Power Management
Battery to field switch delay
Field to battery switch delay
tBFS
VBatt = 6.5 V
tFBS
5
10
13
4688B–RFID–12/04
AC Characteristics (Continued)
Supply voltage VDD = 1.8 V to 6.5 V, VSS = 0 V, Tamb = -40° C to 85° C unless otherwise specified
Parameters
Test Conditions
Pin
Symbol
Min.
500000
Typ.
Max.
9
12
Unit
EEPROM
Endurance
Erase/write cycles
ED
Data erase/write cycle time
For 16-bit access
tDEW
Data retention time
Tamb = 25° C
tDR
Cycles
10
ms
years
Power up to read operation
tPUR
0.2
ms
Power up to write operation
tPUw
0.2
ms
10
ms
Reset
Power-on reset
VDDrise = 0 to 2 V
trise
NRST
VIl < 0.2 VDD
tres
1
µs
Figure 8. Typical Reset Delay After Switching VDD On
600
500
tRESDEL (µs)
VDD
NRST
400
tRESDEL
300
200
100
0
1.0
2.0
3.0
4.0
5.0
6.0
VDD (V)
Figure 9. Typical Reset Delay After Switching VDD On
5.5
5 ms
5.0
VDD
NRST
tRESDEL (ms)
4.5
tRESDEL
4.0
3.5
3.0
2.5
1.0
2.0
3.0
4.0
5.0
6.0
VDD (V)
14
U3280M
4688B–RFID–12/04
U3280M
Figure 10. VDD Rise Time to Ensure Power-on Reset
6
5
VDD (V)
4
3
2
Not allowed
1
0
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
t rise (ms)
15
4688B–RFID–12/04
Ordering Information
Extended Type Number
Package
Remarks
U3280M-NFB
SSO16
Tube
U3280M-NFBG3
SSO16
Taped and reeled
Package Information
16
U3280M
4688B–RFID–12/04
U3280M
Revision History
Please note that the following page numbers referred to in this section refer to the
specific revision mentioned, not to this document.
Changes from Rev.
4688A-RFID-03/03
to Rev.
4688B-RFID-12/04
1. Page 10: Data Transfer Sequence: Text changed
2. Page 13: Antanna: Text changed
3. Page 16: Ordering Information table changed
4.
17
4688B–RFID–12/04
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