For further information contact your local STMicroelectronics sales office.
November 2016 DocID030076 Rev 1 1/7
STS3921 STS3922
boostedNFC analog front-end with active load modulation
Data brief
Features
Supply voltage range from 2.7 V to 3.6 V
Operating temperature: -25 °C to 85 °C
Extended read range in card emulation mode
with antennas below 100 mm2
– boostedNFC technology, based on active
load modulation
– Internal timing defined by VCO locked to
reader frequency
– Delay compensation and synchronization
to ensure transmission in phase with
reader field
– Adjustable initial phase
– Low-impedance output driver
– Automatic output power control to avoid
communication holes
Automatic antenna tuning (STS3922 only)
High degree of Interoperability
– Automatic power control
– Automatic gain control
EMVCo™, ISO/IEC 14443, JIS (X) 6319-4
compliance for full interoperability with existing
payment and ticketing infrastructure.
Card emulation supporting:
– ISO/IEC 14443 Type A 106 kbps
– ISO/IEC 14443 Type B 106 kbps
– FeliCa™ 212 kbps
Interface to dual-interface microcontroller to
boost card emulation performance
– Contactless or NFC-WI interface to SE
– Power supply switch for SE
Low power consumption
– Low power in Wakeup mode
– Mechanism to power the SE at field
detection
Simple system integration
– SPI interface and on-chip EEPROM for
operating option settings
Delivery forms:
– STS3922 delivered as bare dice
– STS3921 in small footprint, with low overall
cost of ownership: wafer-level chip-scale
package (WLCSP)
Applications
boostedNFC products are ideal for NFC
applications on small-footprint devices, such as
wearable devices.
boostedNFC products are intended for two types
of embedded applications:
In combination with a dual-interface chip such
as an ST31G480 secure microcontroller to
allow payment and ticketing on smart devices
In combination with RFID tag ICs to allow
specific features such as Bluetooth®/Wi-Fi®
pairing through NFC, and communication to a
microcontroller through an RF interface.
WLCSP20 (STS3921)
Wafer (STS3922)
www.st.com
Description STS3921 STS3922
2/7 DocID030076 Rev 1
1 Description
The STS3921 and STS3922 products are a family of advanced analog front-ends with ST’s
unique boostedNFC technology. They are ideal for applications that require the card
emulation functionality, but are environmentally challenged or have limited space for the
antenna. This solution allows for a simpler design than the conventional NFC controller-
based architecture, and occupies a board footprint around one-third smaller.
The boostedNFC technology from ST overcomes the main difficulties seen in these
applications when using passive load modulation through generating a tag response with
active transmission. This allows for tag-to-reader communication at coupling factors that are
one order of magnitude lower than conventional methods. When compared to passive NFC
implementations, boostedNFC increases the usable operating volume by up to 900%. The
consumer’s experience during contactless transactions is easy, quick, and completely
reliable, whether for payments in shops, ticketing in metro/urban mass transit
infrastructures, or access control.
boostedNFC products are compliant with the ISO 14443 and FeliCa™ protocols. An
onboard EEPROM allows optimal operational settings to be selected and programmed by
the customer.
The STS3921 is provided in 20-bump wafer-length Chip-scale package (WLCSP20)
whereas the STS3922 are delivered as bare dice.
In order to meet environmental requirements, ST offers this device in different grades of
ECOPACK® packages, depending on their level of environmental compliance. ECOPACK®
specifications, grade definitions and product status are available at: www.st.com.
ECOPACK® is an ST trademark.
DocID030076 Rev 1 3/7
STS3921 STS3922 Software and hardware development package
6
2 Software and hardware development package
ST provides a comprehensive development and design package to:
Simplify software integration: ST lowers the cost for developers by providing multi-
application support with optimized solutions including intuitive SDK platforms for
integrating contactless services around any microcontroller wearable device
architecture.
Simplify hardware integration: ST provides a set of reference designs, expansion
boards and design guidelines.
Simplify deployment: ST provides turnkey solution partnership with OS vendors and
precertification services to help to reduce the time to market as well as development
costs.
STS3921/STS3922 block diagrams and implementation schematics STS3921 STS3922
4/7 DocID030076 Rev 1
3 STS3921/STS3922 block diagrams and implementation schematics
Figure 1 and Figure 2 show the block diagrams of the STS3921 and STS3922 devices, respectively.
Figure 1. STS3921 block diagram Figure 2. STS3922 block diagram
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DocID030076 Rev 1 5/7
STS3921 STS3922 STS3921/STS3922 block diagrams and implementation schematics
6
Figure 3 illustrates how the STS3921 and STS3922 devices are connected in applications
involving a secure element or an RFID tag.
Figure 3. Example application schematic diagram
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7
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