AS3955
NFC Forum Compliant Dynamic Tag
General Description
AS3955 NFC Dynamic Tag IC is the ultimate solution to easily
add NFC functionality to electronic devices. Thanks to a high
sensitivity ISO14443A frontend and high integrated resonance
capacitor, AS3955 offers standalone NFC passive tag
functionality in a small footprint. Fast system integration and
high speed data transfer are guaranteed by the available SPI
and I²C interfaces and by the optimized protocols (Tunneling
Mode and Extended Mode), allowing bidirectional
communication between the device microcontroller and an
external NFC compliant device or ISO14443A reader device
(PCD).
AS3955 is able to operate fully powered by the RF field, without
any external supply. This, combined with an advanced energy
harvesting feature, greatly increases battery life time or even
allows batteryless designs.
AS3955 is used with an appropriate antenna coil connected to
the terminals LC1 and LC2, and behaves as a standard passive
ISO 14443A tag (PICC). After the anti-collision protocol stage,
based on configuration, AS3955 can operate as a standalone
NFC Forum Type 2 Tag or, when tunneling mode is activated, as
a bridge between the PCD and the microcontroller, e.g. to
emulate a custom or standard ISO14443A Level 3 or Level 4 PICC
or a NFC Forum tag. A configurable wake-up signal notifies the
microcontroller on ongoing RF activities, in order to minimize
overall power consumption.
AS3955 includes an embedded EEPROM memory that can be
accessed from the PCD through the RF link or from the
microcontroller through the slave SPI or I²C interfaces. Part or
all memory can be protected by a 32-bit password, or
permanently locked.
AS3955 supports ISO 14443A up to Level 4 and is designed
according to EMVCo requirements, to enable the emulation of
contactless smart cards or NFC Forum compliant Type 2 or Type
4 Tags.
AS3955 is designed for high reliability, and can operate in a wide
power supply range from 1.65V to 5.5V, in a wide temperature
range from -40°C to 125°C. EEPROM memory reaches
automotive grade quality with endurance of 100000 cycles and
data retention of 10 years at 125°C.
Ordering Information
and
Content Guide
appear at end of
datasheet.
ams Datasheet
[v2-03] 2017-Sep-15
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AS3955 −
General Description
Key Benefits & Features
The benefits and features of AS3955, NFC Forum Compliant
Dynamic Tag are listed below:
Figure 1:
Added Value of Using AS3955
Benefits
Features
•
Type 2 Tag standalone functionality
•
Type 2 or 4 Tag emulation with external MCU
•
ISO 14443A Level 3 or 4 card emulation with
external MCU
•
Operating frequency at 13.56 MHz
•
Bit rate at 106 kbps
•
7-byte UID
•
4 kbit EEPROM (472 bytes of user data)
•
Configurable passive wake-up interrupt
•
Energy harvesting to supply up to 5mA @ 4.5V
(regulated)
•
45 pF integrated resonant capacitor
•
3/4-wire SPI slave interface up to 5 Mbps
•
I²C slave interface up to 1 Mbps
•
Programmable I²C address
•
Wide interface supply range (1.65V to 5.5V)
•
32-bit password memory protection
•
Tunneling and Extended modes for MCU
communication
•
Silent mode (MCU power status detection),
configurable between 1.42V and 3.65V
•
Configurable Chip Kill mode
•
Sawn wafer
•
WL-CSP package (2.125mm x 1.42 mm) @ 0.4mm
pitch thick 600μm, thin 316μm typ
•
10-pin MLPD 3mm x3mm x0.9mm package
•
NFC Forum compliance for full interoperability
•
NFC Forum compliance
•
ISO 14443A compliance up to Level 4
•
Choice of memory size based on application
•
Allows zero-power standby
•
Enables long battery life time, or batteryless
designs
•
Allows fast antenna prototyping (ISO antenna
classes 1 to 6)
•
Design flexibility, easy integration. Fits
requirements for various embedded applications
•
Design flexibility, easy integration
•
Fits supply requirements for various applications,
including industrial
•
Support for multiple applications, and storage of
sensitive data
•
High performance and robust data
communication, allows custom protocols to be
implemented
•
Consistent NFC behavior of battery supplied
devices in e.g. pairing applications
•
Possibility to disable RF communication
•
Small outline, compatibility to common inlay and
card manufacturing lines, surface-mount
assembly
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ams Datasheet
[v2-03] 2017-Sep-15
AS3955 −
General Description
Applications
AS3955 is suited to a wide range of applications, including
•
NFC connection handover (Bluetooth™,
Bluetooth Low Energy, Wi-Fi pairing)
•
Equipment setup, service and configuration
•
Firmware upgrades
•
Activity and status logging
•
Wireless authentication (e.g. access control to buildings
and equipment)
Typical Markets:
•
Consumer electronics, wearables and smart clothing
•
Home appliances
•
Automotive
•
Industrial equipment and building automation
•
Remote sensing
•
Gaming
•
EMV payment cards
A typical system diagram is depicted in
Figure 2.
At the presence of a 13.56 MHz field generated by a NFC device,
AS3955 powers up, notifies the microcontroller through a
wake-up signal and handles the tag activation sequence.
Depending on configuration, several operations are then
possible:
•
AS3955 exchanges with the NFC device NDEF data stored
in the internal EEPROM
•
The microcontroller exchanges with the NFC device NDEF
data stored in external memory
•
The microcontroller exchanges data with AS3955. This
operation can be performed concurrently with
communication over the RF link, or also in absence of RF
power, in presence of an external supply.
Figure 2:
Typical System Diagram
I²C or SPI
AS3955
wake-up
microcontroller
ams Datasheet
[v2-03] 2017-Sep-15
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AS3955 −
General Description
This built-in flexibility makes it ideal for a number of
applications requiring non-volatile memory to be accessed
when the system is not powered, e.g.:
•
personalization data is programmed by the NFC device
(even in case SPI / I²C is not powered) and it is later read
by microcontroller through SPI / I²C interface
•
Log data is stored periodically by the microcontroller and
can then be read by the NFC device even when the
microcontroller is not powered
•
A NDEF message is regularly modified by the
microcontroller (e.g. Bluetooth pin code, or Wi-Fi key, or
dynamic URL) and it is later read by a NFC device.
Block Diagram
The functional blocks of this device are shown below:
Figure 3:
AS3955 Block Diagram
VP_REG
(Programmable
1.8-4.5V, 5mA max)
VP_INT
2.0V typ
LC1
AFE
POWER
MANAGER
VDD
AS3955
VP_IO
IRQ
45pF
NFC FORUM
TYPE 2 TAG
LOGIC
LC2
EEPROM
4kbit
I²C/SPI
INTERFACE
I²C/SPI
VSS
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ams Datasheet
[v2-03] 2017-Sep-15
AS3955 −
General Description
AS3955 is composed of NFC-A Analog Front End (AFE), NFC Type
2 Tag Logic, EEPROM, SPI / I²C Interface and Power Supply
Manager Block (Power Manager).
The AFE is connected to an external tag coil which forms,
together with integrated resonant capacitor, a LC tank
resonating with the external electromagnetic field frequency
of 13.56 MHz. The AFE has built-in rectifier and regulators. The
output of the internal regulator (VP_INT) is used to supply the
AFE and also the Logic and EEPROM (through Power Supply
Manager). A regulator output VP_REG is available on a pin to
supply external circuitry by harvesting energy from the RF field.
The Power Manager is controlling the power supply of Logic
and EEPROM. The two blocks can be supplied either from
VP_INT or from VP_IO (SPI / I²C power supply) depending on
the power mode of the chip. AS3955 offers a power mode where
VP_IO supply is switched to VP_INT whenever the RF field is
present. VP_IO is typically used when some activity is started
over the SPI / I²C and the VP_INT is too low to be used as a power
supply.
The Logic is responsible for handling the anti-collision
sequence, when acting as NFC Type 2 Tag, and other data
transfer. The interface logic contains also a 32-byte buffer for
block transmission between NFC device and AS3955.
The EEPROM is used to store the UID, configuration and control
bits, and user data which can be accessed also via the SPI / I²C.
ams Datasheet
[v2-03] 2017-Sep-15
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