AUTHENTEC EntrePad AES2501A User manual

2317Rev 1.1 (17NOV04)
EntréPad AES2501A FINGERPRINT SENSOR
Product Specification
For Universal Serial Bus Applications
Hardware Reference
2317 Rev 1.1
November 17, 2004
AuthenTec Confidential Information
AuthenTec, Inc.
Post Office Box 2719
Melbourne, Florida 32902-2719
321-308-1300
www.authentec.com

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 2
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AuthenTec, Inc.
Post Office Box 2719
Melbourne, Florida 32902-2719
321-308-1300
www.authentec.com
[email protected]
AuthenTec, FingerLoc, EntréPad, Aware, AES2501A, AES3550, AES4000, AF-S2, ISX, TruePrint, the AuthenTec
colophons and logotypes, and the phrase “Personal Security for the Real World” are trademarks of AuthenTec, Inc.
Microsoft and Windows 98 are registered trademarks of Microsoft Corp. Microwire™ is a trademark of National
Semiconductor Corp. SPI™is a registered trademark of Motorola. All other trademarks are the property of their
respective owners.
Product Specification for the AES2501A Fingerprint Sensor
Copyright ©2004 by AuthenTec, Inc. No part of this publication may be reproduced in any form or by any means without prior written
permission. Printed in the United States of America.

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 3
Table of Contents
1. INTRODUCING THE ENTRÉPAD AES2501A SLIDE SENSOR…..........................................................6
1.1 TRUEPRINT TECHNOLOGY IS…..............................................................................................................6
1.2 FEATURE SUMMARY..............................................................................................................................6
1.3 CONVENTIONS ......................................................................................................................................7
1.4 OPERATIONAL DESCRIPTION..................................................................................................................7
1.5 NAVIGATION USING THE AES2501A......................................................................................................8
2. DC ELECTRICAL CHARACTERISTICS ..................................................................................................9
2.1 ABSOLUTE MAXIMUM RATINGS ..............................................................................................................9
2.2 RECOMMENDED OPERATING CONDITIONS ..............................................................................................9
2.3 DC CHARACTERISTICS @RECOMMENDED OPERATING CONDITIONS.....................................................10
3. SENSOR OPERATION ...........................................................................................................................11
3.1 OPERATION DESCRIPTION ...................................................................................................................11
3.2 INTERNAL CHIP BLOCK DIAGRAM .........................................................................................................12
4. PACKAGING & PIN DEFINITIONS ........................................................................................................13
4.1 PACKAGING INFORMATION...................................................................................................................13
4.2 PIN LIST .............................................................................................................................................15
4.2.1 Pin Type and Activity Definitions...............................................................................................16
4.3 PIN DESCRIPTIONS..............................................................................................................................17
4.4 CLOCK SELECT CONTROL ...................................................................................................................18
4.4.1 Clock Specification....................................................................................................................18
4.5 TIMING INFORMATION ..........................................................................................................................20
4.5.1 Image Scan Timing....................................................................................................................20
4.5.2 USB Interface............................................................................................................................20
4.5.3 Finger Detect Auto-calibration...................................................................................................20
5. SYSTEM INTERFACE DESCRIPTIONS ................................................................................................21
5.1 INTERFACE SELECT CONTROL .............................................................................................................21
5.2 USB INTERFACE .................................................................................................................................22
5.3 RESET................................................................................................................................................24
6. SOFTWARE INTERFACE DETAILS ......................................................................................................25
6.1 REGISTER MAP...................................................................................................................................25
6.1.1.1 Control Register 1 (CTRL1) (80h).....................................................................................................27
6.1.1.2 Control Register 2 (CTRL2) (81h).....................................................................................................28
6.1.1.3 Excitation Common Controls (EXCITCTRL) (82h)..............................................................................29
6.1.1.4 Detect Control (DETCTRL) (83h) ....................................................................................................30
6.1.1.5 Navigation Correlation Range (NAVCORRNGE) (84h) .......................................................................31
6.1.1.6 Navigation Finger Detect Threshold (NAVFDTHRSH) (85h)................................................................31
6.1.1.7 Navigation Control (NAVCTRL) (86h)...............................................................................................32
6.1.1.8 Detect Frequency (DETFREQ) (87h)................................................................................................33
6.1.1.9 Column Scan Rate (COLSCAN) (88h)..............................................................................................34
6.1.1.10 Measure Drive (VDCTRLMD) (89h)..................................................................................................35
6.1.1.11 Measure Frequency (MEASFREQ) (8Ah)......................................................................................36
6.1.1.12 Demod Phase 1(DEMODPHASE1) (8Ch) .....................................................................................37
6.1.1.13 Channel Gain (CHANGAIN) (8Eh)................................................................................................38
6.1.1.14 Channel Bias (CHANBIAS) (8Fh).................................................................................................39
6.1.1.15 Carrier Null (CARRNULL) (90h)...................................................................................................40
6.1.1.16 A/D Reference High (ADREFHI) (91h) .........................................................................................41
6.1.1.17 A/D Reference Low (ADREFLO) (92h).........................................................................................41
6.1.1.18 Start Column (STRTCOL) (95h) ..................................................................................................42
6.1.1.19 End Column(ENDCOL) (96h) ......................................................................................................42

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 4
6.1.1.20 Data Format (DATFMT) (97h)......................................................................................................43
6.1.1.21 Image Data Control (IMAGCTRL) (98h) ........................................................................................44
6.1.1.22 GPIO Data (GPIODATA) (99h)....................................................................................................45
6.1.1.23 Sensor Status (STAT) (9Ah)........................................................................................................46
6.1.1.24 Challenge Word 1 (CHWORD1) (9Bh) .........................................................................................47
6.1.1.25 Challenge Word 2 (CHWORD2) (9Ch).........................................................................................47
6.1.1.26 Challenge Word 3 (CHWORD3) (9Dh).........................................................................................48
6.1.1.27 Challenge Word 4 (CHWORD4) (9Eh) .........................................................................................48
6.1.1.28 Challenge Word 5 (CHWORD5) (9Fh)...........................................................................................48
6.1.1.29 Test Register 1 (TREG1) (A1h) ...................................................................................................49
6.1.1.30 FD Threshold (FDTHRESHOLD) (A8h)........................................................................................50
6.1.1.31 Miscellaneous Control (MISCCTRL) (ACh) ...................................................................................51
6.1.1.32 Single Reg. Address (SREGADDR) (ADh)....................................................................................52
6.1.1.33 FDRV X HI (FDRVXHI) (AEh)......................................................................................................53
6.1.1.34 FDRV X LO (FDRVXLO) (AFh)....................................................................................................53
6.1.1.35 Watchdog Control (WDCtrl) (B0h) ................................................................................................54
6.1.1.36 Misc. Image Control/GPIO Disable(MISCICTRL) (B3h)...................................................................55
6.1.1.37 SOF Timestamp/FreeRun[13:7] (SOFTIMEHIGH) (BAh) ................................................................56
6.1.1.38 SOF Timestamp/FreeRun[6:0] (SOFTIMELOW) (BBh)...................................................................56
6.1.1.39 EOF Timestamp[13:7] (EOFTIMEHIGH) (BCh).............................................................................56
6.1.1.40 EOF Timestamp[6:0] (EOFTIMELOW) (BDh)................................................................................57
7. DATA FORMATS ....................................................................................................................................58
7.1 OVERVIEW..........................................................................................................................................58
7.1.1 Registers Message Format.......................................................................................................59
7.1.2 Image Data Format – Grey Scale 500 ppi.................................................................................59
7.1.3 Image Data Format – 250 ppi....................................................................................................60
7.1.4 Image Data Format – Monochrome ..........................................................................................61
7.1.5 Histogram Message Format......................................................................................................62
7.1.6 Authentication Word Message Format......................................................................................63
8. PART NUMBERING SCHEME................................................................................................................64
9. REVISION HISTORY...............................................................................................................................65

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 5
LIST OF FIGURES
Figure 1-1 Row Numbering..............................................................................................................................7
Figure 2-1 Absolute Maximum Ratings............................................................................................................9
Figure 2-2 Recommended Operating Conditions ............................................................................................9
Figure 2-3 DC Characteristics........................................................................................................................10
Figure 3-1 AES2501A Functional Diagram.....................................................................................................11
Figure 3-2 Internal Chip Block Diagram.........................................................................................................12
Figure 4-1 Pin List by Interface......................................................................................................................16
Figure 4-2 AES2501A Active Pin Functional Description ..............................................................................17
Figure 4-3 External Clock Specifications.......................................................................................................19
Figure 5-2 SIO Pin Definitions for the USB Interface.....................................................................................21
LIST OF TABLES
Table 4-1 CLKSEL[2:0] Decode 18
Table 5-2 Device Descriptor 22
Table 5-3 Default Configuration Descriptor 23
Table 5-4 Default Interface 0, Alternate Setting 0 Descriptor 23
Table 5-5 Default Interface 0, Alternate Setting 0, Bulk Endpoint Descriptors 23
Table 5-6 String 0 Descriptor 24
Table 6-1 Registers Summary 26
Table 7-1 Command Byte Definition 58
Table 7-2 Gray Scale Message Format 59
Table 7-3 4 Bit 250 ppi Gray Scale Message Format 60
Table 7-4 Monochrome Packed Message Format 61
Table 7-5 Histogram Message Format 62
Table 7-6 Authentication Word Message Format 63

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 6
1. Introducing the EntréPad AES2501A Slide Sensor…
…, the latest, lowest cost fingerprint sensor IC for PC Applications. AuthenTec has adapted its
patented, award winning TruePrint Technology to read fingerprints while the finger is pulled
across the AES2501A's rectangular surface. In this manner, the fingerprint images are
acquired AND the sensor is substantially reduced in size.
The AES2501A combines silicon-based image slice capture with proprietary sensor control
and image segment matching algorithms to provide the best quality lowest cost biometric
authentication solution available.
1.1 TruePrint Technology is…
…AuthenTec’s unique patented fingerprint reading technology. During imaging, a small signal
is generated between the IC and the finger’s living tissue layer. 3072 individual sensing
elements in the slide sensor matrix form a planar antenna array that receives this signal,
creating a digital pattern that accurately reproduces the fingerprint’s underlying structure.
A powerful utility contained within TruePrint Technology™ is Dynamic Optimization™. This
tool analyzes each image, controlling up to 15 parameters real-time to optimize the fingerprint
image slices, regardless of unusual skin conditions or surface contamination. This functionality
is built right into the sensor hardware or you can perform these functions in software for total
control and upgrade-ability.
1.2 Feature Summary
9Patented TruePrint Technology for best
Ability To Acquire (ATA)
9High Definition 192 X 16 TruePrint
Technology Based Pixel Array
o500 pixels per inch (ppi) native
o9.75mm X 0.81mm array area
9Compact 48 Ball Grid Array (BGA)
Package
o13.8mm X 5mm X 1.3mm
9USB Operating Voltage Range
o3.0V to 3.6V single supply
90°C to +70°C operating temperature range
9Easy to Integrate USB 2.0 Full Speed
9Operation with Crystal, Resonator, or with
external clock input
9Ultra-hard scratch resistance surface coating
o> 1 Million rubs w/o degradation
9IEC 61000-4-2 Level 4 ESD Capability (+/- 15KV)
9Built-in low power Finger Detection w/system interrupt capability
9Multiple battery-friendly operating modes @ 3.3V
oImaging @ <40mA typ.
o5-way Navigation @ < 3mA typ.

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 7
1.3 Conventions
For vectors (groups of bits), ordering will always be from MSB to LSB (e.g.
Pixel_Data[63:0] where bit 63 is the MSB and bit 0 is the LSB).
When vectors that span multiple bytes are transmitted, the lower byte (bits
[7:0]) is transmitted first. This applies to pixel data and the authentication
word returned after each imaging frame.
Numbers followed by a ‘b’ are shown in binary. Numbers followed by an
‘h’ are in hexadecimal.
1.4 Operational Description
The Sensor begins operation in the ‘idle’ state after a reset. In the idle
state, array power is turned off and clocking is disabled (except to support
interface activity). It is then necessary for the system SW to program the
sensor for the desired operation (Imaging or Navigation). After this setup,
the requested operation is enabled by setting the Op Enable bit (located in
Register 80h:D2). If Imaging is selected, the Sensor enters finger detect
mode checks for a finger present at a rate programmed by the Finger
Detect Rate setting. The default reset value sets the detect period to ~62
ms.
After finger detection, the sensor will begin the programmed operation and
will enter Imaging mode until the finger is removed. Once the finger is
removed, the sensor returns to the Low Power Finger Detect mode.
When no activity is detected on the system interface bus for approximately
200uS, power is reduced by disabling the internal clocks and the array
power is once again turned off.
Figure 1-1 Row Numbering

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 8
The array consists of 192 columns of 16 pixels each. During imaging, the
columns are powered up and the signals from each of the 16
pixels/column are sampled, digitized and returned to the host computer
over the selected interface sequentially in order on a per-column basis.
The sensor has the capability to utilize only the center 128 columns during
imaging mode to facilitate higher finger sliding speeds. During fingerprint
enrollment, a 192 pixel wide template is created. Then, optionally, either a
192 pixel wide or 128 pixel wide verify can be performed. This mode is
entirely controlled via software using sensor register settings for start and
stop columns.
If the finger detect is not active when it is rechecked at the end of a scan,
the array is powered down and the sensor reverts back to checking for a
finger at the programmed detect rate.
AuthenTec has application notes to support the integration of the
AES2501A for all available interface options. Contact AuthenTec for
availability.
1.5 Navigation Using the AES2501A
The navigation use model is a button replacement system. The typical
Left / Right / Up / Down button functionality can be easily emulated on the
sensor by statically touching the sensor to indicate desired left or right
direction and by sliding the finger at normal finger speeds in the up or
down direction to indicate up or down.
When operations are enabled (via the OP ENABLE bit as described
previously) and Navigation mode is selected, the sensor will provide
constant, periodic indications of direction and finger presence by sending
a 2-byte message to the selected interface.
After NAV mode is enabled, the sensor takes 10 samples of the center
column approximately every 100 us. After producing an output message,
the sensor then enters a low power state for a programmable amount of
time, and then repeats the above sequence. Output generation rates are
programmable and range from 100 Hz down to 26 Hz.

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 9
2.DC ELECTRICAL CHARACTERISTICS
2.1 Absolute Maximum Ratings
An absolute maximum rating is the maximum value guaranteed by the
AuthenTec. The use of a product in violation of these ratings can result in
significant loss of device reliability or cause damage to the IC.
Symbol Parameter Min. Max. Units
VDD Supply Voltage -0.5 4.3 V
VIInput Voltage -0.5 VDD+0.5 V
VOOutput Voltage -0.5 VDD+0.5 V
IIK Input Clamp Current
VI < VSS of VI> VDD ±20 mA
IOK Output Clamp Current
VO < VSS of VO> VDD ±20 mA
TSTG Storage Temperature -65 150 °C
Latch-Up Latch-Up Immunity
JEDEC JESD78 ±100 mA
TSOL Soldering Temperature +240 °C
ESDPIN Pin-level ESD Immunity
JESD22 Method A114-B -2000 +2000 V
ESDPACKAGE Package-level ESD
Immunity
IEC61000-4-2 Level 4 Air
Discharge method using
AuthenTec approved
reference design
-15 +15 KV
Figure 2-1 Absolute Maximum Ratings
2.2 Recommended Operating Conditions
Symbol Parameter Min. Typ Max. Units
VDD Supply Voltage 3.0 3.3 3.6 V
VDDACp-p Power Supply Ripple -50 0 +50 mV
VIInput Voltage 0 VDD V
VOOutput Voltage 0 VDD V
VIH High Level Input Voltage 70% VDD V
DD V
VIL Low Level Input Voltage 0 30% VDD V
ttInput Transition (Rise and Fall)
Time 0 3 ns
TAAmbient operating temperature 0 70* °C
Figure 2-2 Recommended Operating Conditions

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 10
*Warning
The AES2501A remains fully operational at temperatures that are high enough to be
uncomfortable for the user.
For reasons of safety and protection, AuthenTec reference designs include circuitry that
serves to manage the junction temperature by controlling the supply current. If the
hardware developer elects not to use the AuthenTec-provided control circuit design, it will
then be essential that an equivalent design be developed and implemented.
2.3 DC Characteristics @ Recommended Operating Conditions
Unless otherwise specified, VI= VDD or VSS, TAmbient = 25°C
Symbol Parameter Conditions Min. Typ Max. Units
VOH High Level Output Voltage IOH=2mA Vdd-
0.3 V
VOL Low Level Output Voltage IOL=2mA 0.3 V
IIL Low Level Input Current VI=VIL(min.) ±1 µA
IIH High Level Input Current VI=VIH(max.
)
±1 µA
IOZ High Impedance State Output
Current ±20 µA
USB Interface Supply Currents
IDDQ Supply Current
Imaging mode; USB (peak) Vdd=3.3V 45 mA
IDDQ Supply Current
Navigation or Finger Detect;
USB
Vdd=3.3V 3 mA
IDDQ Supply Current
Suspend Current; USB Vdd=3.3V 350 uA
Figure 2-3 DC Characteristics
All IDDQ Currents measured RMS using standard AuthenTec software and drivers. Use of other software or
customized register settings may effect actual power consumption.

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 11
3.SENSOR OPERATION
3.1 Operation Description
During an imaging event, the RF TruePrint Signal is conducted via the
Drive Ring to the users’ finger. The TruePrint Signal is them conducted
through and modulated by the “live layer” of the finger where the true
fingerprint originates. The imaging array (center strip region of the chip)
measures the TruePrint signal; the strength of which corresponds to either
a ridge or valley region.
The image array of the AES2501A sensor is composed of 16x192 pixels.
The array is scanned similarly to a sub-array in AuthenTec’s touch
sensors. During the imaging process, 16 pixels in a column are powered
up, sampled, and converted to 4-bit or 2-bit values. The high and low
reference voltages for the ADC are programmable via 7-bit DACs.
TruePrint
Signal
A/D
Converter
High Reference
Low Reference
Pixel Data
Pixel
Sense
Amp
Pixel
Antenna
Plate
Synthesizer
D/A
Converter
Output
Buffer
Drive
Rin
g
Figure 3-1 AES2501A Functional Diagram
The sensing element of each pixel is an RF sense-amplifier, which picks
up the TruePrint (high frequency AC) signal (125 KHz – 2MHz) that is
applied to the finger via the Finger Drive Ring, located prominently on the
sensor surface which fully encloses the pixel array. The pixel sense amps
receive, amplify, and buffer the signal.
Each pixel output is then converted into a level corresponding to the
strength of the received signal. Stronger signals are picked up from ridges
than valleys. This output is converted by an A/D converter whose
endpoints are adjustable via the Reference High and Reference Low
voltages.

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 12
3.2 Internal Chip Block Diagram
The following diagram shows a top-level block diagram of the Sensor IC.
Pixel
Array
Row
Ctrl
Column Ctrl
Analog
Channel
Serial
A/D
Registers Scan Timing
And Control
Synthesizer Excitation
Generator
USB
Input USB
Interface
Finger Ring
Drive
USB
Interface USB
Output
Figure 3-2 Internal Chip Block Diagram

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 13
4.Packaging & Pin Definitions
4.1 Packaging Information
The AES2501A sensor is housed in a plastic 48 Ball Grid Array package.
The most current PDF version of this package drawing can always be
viewed, printed, or downloaded at:
http://www.authentec.com/products/docs/AES2501A_48_BGA_Pkg.pdf

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 14
The package drawing shows both the mechanical dimensions of the
package as well as recommended housing “keep-out” areas and angles of
approach to and from the slide surface. For additional information,
contact AuthenTec Applications Engineering for more details.
The Pin 1 indicator is a gold triangle located in the corner of the package
adjacent to pin one.
Post-assembly top-side inspection can be performed visually using the
fact that the drive bars are of different thickness (One Bar is 0.84mm, the
other is 0.70mm). When the thicker drive bar is located at the top of the
device from the inspection viewpoint, pin one is located top left from the
same perspective.
The “X-Ray” view below shows the perspective described.
Pin 1 Triangle on the bottom, Thicker Drive Bar on the top.

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 15
4.2 Pin List
Pin assignments and pin function descriptions of the AES2501A sensor are given
below. Shared pin definitions for SIO[8:0] are selected by the state of the
IOSEL[1:0] pins. Refer to section 5.1 for the interface-specific SIO definitions. The
following pin lists match AuthenTec certified reference designs. Certain pin
functions will be required to change for other implementations.
Pin Type Digital Activity Signal
Name (USB)
A1 Passive Static VREF
A2 Passive Static CT2
A3 Passive Static CT1
A4 Output Active FINGERDRIVE
A5 Input Static RESET*
A6 Reserved N/C
A7 Reserved N/C
A8 Power VDD
A9 Power GND
A10 Passive Static PLL_FILTER
A11 Input Active SYS_CLK
A12 Output Active DRIVE_RING
B1 Input Static CLKSEL2
B2 Power GND
B3 Power VDD
B4 Input Static VDDL
B5 Input Static VDDL
B6 Input Static CLKSEL1
B7 I/O Active SUSPEND
B8 I/O Active USB_OE*
B9 I/O Active D+
B10 I/O Active D-
B11 I/O Active PID3
B12 I/O Active PID2
C1 Reserved N/C
C2 Power VSS
C3 Power VDDA
C4 Input Static VSSL
C5 Input Static CLKSEL0
C6 Input Static VSSL
C7 I/O Active PID0
C8 I/O Active PID1
C9 I/O Active ENUM
C10 Output Active VDDA_ON*
C11 Power VSS
C12 Power VDDA
D1 Output Active DRIVE_RING
D2 Reserved N/C
D3 Reserved N/C
D4 Reserved N/C

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 16
Pin Type Digital Activity Signal
Name (USB)
D5 Reserved N/C
D6 Reserved N/C
D7 Reserved N/C
D8 Power OVC_VDD
D9 Output Static OVC_DET
D10 Power OVC_VDDA
D11 Input Static OVC_SENSE
D12 Power VSS
Figure 4-1 Pin List by Interface
4.2.1 Pin Type and Activity Definitions
Power: Power Supply Connections
Passive: Connections to passive components (ex: Filter caps, etc)
Input: Active Inputs to the sensor
Output: Active Outputs from the sensor
I/O: Active I/O’s from the sensor (state / configuration dependent)
Reserved: Do Not Connect anything to these pins
Static: DC or slowly changing voltages
Active: Active Signals, Digital or Analog
VDDL: Fixed Active High Logic Level
VSSL: Fixed Active Low Logic Level
VDDA: Pixel Array Power supply pin

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 17
4.3 Pin Descriptions
Pin Signal Name Function Description
For pins D8-D12, Refer to the appropriate AuthenTec Reference Design for connection
details
C5 CLKSEL0 Clock input option selection. Refer to section 4.4
B6 CLKSEL1 Clock input option selection. Refer to section 4.4
B1 CLKSEL2 Clock input option selection. Refer to section 4.4
A3 CT1 Filter Capacitor - connect to pin A2 through a 0.1uF capacitor, standard bypass type
A2 CT2 Filter Capacitor - connect to pin A3 through a 0.1uF capacitor, standard bypass type
D1 DRIVERING DriveRing - connection to the metal ring on the sensor surface. No other connections
made.
A12 DRIVERING DriveRing - connection to the metal ring on the sensor surface. No other connections
made.
A4 FINGERDRIVE
TruePrint Signal output used to drive radio frequency signal through external circuitry to
finger ring pins (A12 and D1). Controlled by internal excitation generator.
D9 OVC_DET Over Current Detect Power Off output - Active low for power on. Refer to reference design
schematics for connection details.
D11 OVC_SENSE Load side of current sense resistor input for over current control. Refer to Ref. Design
D8 OVC_VDD Over Current Detect Circuit Digital Power Supply Pin (V) Refer to Ref. Design
D10 OVC_VDDA Over Current Detect Circuit Analog Power Supply Pin (V) Refer to Ref. Design
A5 RESET* Reset input - 2/3 threshold voltage with hysteretic input. Approximately 57 Kohm pull-up
resistor internal, with tolerance of 30%. See section 5.3 for additional definition of a proper
reset.
B8 SIO0 Refer to Figure 5.1
B7 SIO1 Refer to Figure 5.1
C7 SIO2 Refer to Figure 5.1
C8 SIO3 Refer to Figure 5.1
B12 SIO4 Refer to Figure 5.1
B11 SIO5 Refer to Figure 5.1
B10 SIO6 Refer to Figure 5.1
B9 SIO7 Refer to Figure 5.1
C9 SIO8 Refer to Figure 5.1
A11 SYS_CLK Clock input pin - input clock used for all chip functions. See Figure 4-3 and Section 4.4 for
input characteristics and requirements.
C12 VDDA Pixel Array Power Connection
C3 VDDA Pixel Array Power Connection
C10 VDDA_ON* External Array Power FET control - If used this pin may drive a high side P-channel FET.
See AuthenTec Reference Designs for connection details.
A1 VREF Voltage Reference output - to be connected to a capacitance of 0.22uF to ground,
standard bypass type
D12 VSSOD Over Current Detect Circuit Return Supply pin (GND)
A10 PLL_FILTER Refer to USB Reference Design Schematic for appropriate filter components / connection
Figure 4-2 AES2501A Active Pin Functional Description

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 18
4.4 Clock Select Control
AES2501A can support a variety of clock sources, ranging in frequency
from 6MHz up through 48MHz. The AES2501A uses a single pin
crystal/resonator oscillator circuit that can also be overdriven with an
external clock source. Clock frequency selection [including clocks driven
into the SYS_CLK pin] is done via the CLKSEL[2:0] input pins. The
following table shows the CLKSEL[2:0] pin configurations:
CLKSEL2
Pin B1 CLKSEL1 Pin B6 CLKSEL0 Pin C5 Crystal/Resonator or Clock Frequency
0 0 0 6 MHz
0 0 1 Reserved
0 1 0 12 MHz
0 1 1 18 MHz
1 0 0 24 MHz
1 0 1 Reserved
1 1 0 Reserved
1 1 1 48 MHz (PLL Bypass, clock only)
Table 4-1 CLKSEL[2:0] Decode
For USB applications, Crystal/Resonator frequency options include 6, 12, 18, and
24MHz.
4.4.1 Clock Specification
For the AES2501A, there are several different clocking options available:
Crystal connection, ceramic resonator connection, and external clock
driven. Appropriate application of clock sources is driven the desired
circuit application (interface type) and reference design. This section
addresses the specification requirements for an externally driven clock.
All electrical and environmental conditions from the device specification
apply as well.

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 19
When driving an external clock into the SYSCLK device pin, the following
timing diagram applies:
[1] Parameter [1] Minimum [1] Maximum
[2] Freq. (USB
Interface) [2] 12MHz – 0.25% [2] 12MHz + 0.25%
[3] Jitter (USB
Interface) [3] [3] 0.2ns
[4] Tr [4] - [4] 3ns
[5] Tf [5] - [5] 3ns
[6] Thigh [6] 45%*[Tperiod] [6] 55%*[Tperiod]
[7] Tlow [7] 45%*[Tperiod] [7] 55%*[Tperiod]
Figure 4-3 External Clock Specifications

2317 Rev 1.1 (17NOV04) AuthenTec Confidential Information 20
4.5 Timing Information
.
4.5.1 Image Scan Timing
The fastest scan time available is 32us per sixteen pixels and will limit
image frame rates to less than [16x192 pixels * 32us/16 pixels = 6.144
ms] or ~162.7 fps maximum. Transferring register data, histogram data,
and authentication data will reduce this frame rate.
4.5.2 USB Interface
The AES2501A fingerprint sensor is as a USB low power device. This
requires that the total current consumption be less than 100 mA and
suspend current be less than 500uA. For all timing diagrams, please refer
to the Universal Serial Bus Specification, Version 2.0. The AES2501A
fully supports the USB selective suspend mode (C3 power state).
4.5.3 Finger Detect Auto-calibration
When using Finger Detect [delay method], the device is automatically
calibrated once on power up. Sending a master reset to the device does
not affect the setting of the reference delay value used for the finger
detect calculation. If desired, the device can be re-calibrated by setting
the Recalibrate FD bit [Reg82-D2], which is self-clearing.