Rainbow Electronics DS2705 User Manual

r

m

PASS

FAIL

C

SHA-1 Authentication Maste

DS2705

www.maxim-ic.com

GENERAL DESCRIPTION

The DS2705 provides the master side of a Secure Hash Algorithm (SHA) based token authentication scheme. Hardware-based SHA authentication allows for security without the added cost and complexity of a microprocessor-based system. Batteries and other accessories are authenticated using a single contact through the Dallas 1-WireÒ interface. Authentication is performed on demand or automatically, with the pass/fail status reported on open-drain output pins to signal the charge system and/or drive LEDs. The DS2705 stores a predetermined challenge-andresponse pair in nonvolatile (NV) EEPROM. The DS2705 works in conjunction with Dallas Battery Management SHA-1 token products, including the DS2703 and DS2704.

APPLICATIONS

Digital Cameras Portable DVD and Media Players Cradle and Accessory Chargers Cell Phones/Smartphones

APPLICATION EXAMPLE

PIN CONFIGURATION

HAL

2

3

VSS

MAX

VDD

7

MDQ

6

SDQ

VPP

FEATURES

§ Initiates Challenge-and-Response Authentication based on the SHA-1 Algorithm

§ Dallas 1-Wire Master/Slave Interface Operates at Standard and Overdrive Speeds

§ Input and Output pins for Initiating Challenge and Reporting Authentication Pass/Fail

§ Programmable Configuration

§ Operates from 2.5V to 5.5V Supply

§ Tiny mMAX Package (Pb-Free)

ORDERING INFORMATION

PART TEMP RANGE MARKING PIN-PACKAGE

DS2705U+

DS2705U+/T&R

+ Denotes lead-free package. 1-Wire is a registered trademark of Dallas Semiconductor.

1 of 18 050506

-40°C to +85°C

DS2705

DS2705 DS2705U+ in Tape-and-Reel

mMAX

DS2705: SHA-1 Authentication Master

ABSOLUTE MAXIMUM RATINGS

Voltage Range on All Pins (except VPP), Relative to VSS -0.3V to +5.5V Voltage Range on V

Pin, Relative to VSS -0.3V to +18V

PP

Continuous Source Current, MDQ 20mA Operating Temperature Range -40°C to +85°C Storage Temperature Range -55°C to +125°C Soldering Temperature See IPC/JEDEC J-STD-020A Specification

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to the absolute maximum rating conditions for extended periods may affect device.

DC ELECTRICAL CHARACTERISTICS

(2.5V £ VDD £ 5.5V, TA = -20°C to +85°C.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Active mode, MDQ low, I Active mode, MDQ idle, I

O_MDQ

Sleep mode, I

= 0

= 0 (Note 2) 1 2

O_MDQ

2.5 mA

90 130

mA

Program pulse (Notes 1, 3) 14.5 15.0 V

(Note 1) 1.8 V

(Note 1) 0.6 V

IOL = 4mA (Note 1) 0.4 V

Supply Current

Programming Voltage: VPP

Input Logic High: MDQ, SDQ, CHAL

Input Logic Low: MDQ, SDQ, CHAL

Output Logic Low: MDQ, SDQ V

I

V

DD1

DD2

DD3

PP

IH

IL

OL1

Output Logic Low: PASS, FAIL

Pulldown: VPP

Pulldown: SDQ, CHAL I

Pullup: MDQ

V

OL2

I

PD1

PD2

IOH

VOH

IOL = 10mA (Note 1) 0.4 V

300

(Note 5) 0.125

Communication mode (Note 6)

Computation mode

= 2.0mA (Note 7)

I

OH

0.25 2.5 mA

V

- 0.1

DD

V

mA

Input Capacitance: MDQ, SDQ CIN 60 pF

EEPROM RELIABILITY SPECIFICATION

(2.5V £ VDD £ 5.5V, TA = -20°C to +85°C.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

EEPROM Write Time t

EEPROM Write Endurance N

EEW

EEC

(Note 3) 15 ms

(Notes 3, 4) 1,000 Cycles

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DS2705: SHA-1 Authentication Master

AC ELECTRICAL CHARACTERISTICS: MASTER 1-Wire INTERFACE

(2.5V £ VDD £ 5.5V, TA = -20°C to +85°C.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

STANDARD BUS TIMING

Time Slot t

Recovery Time t

Write-0 Low Time t

Write-1 Low Time t

Read-Data Sample Window t

Reset-Time Low t

Presence-Detect High t

Presence-Detect Low t

OVERDRIVE BUS TIMING

Time Slot t

Recovery Time t

Write-0 Low Time t

Write-1 Low Time t

Read-Data Sample Window t

(Note 10) 90

MSLOT

(Note 10) 7.5 10 12.5

MREC

(Note 10) 88.5

MLOW0

(Note 10) 1.05 1.5 2.25

MLOW1

(Note 10) 4.0 5.5 7.0

MRDV

(Note 10) 510 680 850

MRSTL

(Note 10) 2 75

MPDH

(Note 10) 2 400

MPDL

(Note 10) 12

MSLOT

(Note 10) 1 2 2.5

MREC

(Note 10) 10.5

MLOW0

(Note 10) 0.35 0.5 0.65

MLOW1

(Note 10) 1.1 1.5 1.9

MRDV

ms

Reset-Time Low t

Presence-Detect High t

Presence-Detect Low t

(Note 10) 53 70 88

MRSTL

(Note 10) 2 7

MPDH

(Note 10) 2 41

MPDL

ms

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DS2705: SHA-1 Authentication Master

AC ELECTRICAL CHARACTERISTICS: SLAVE 1-Wire INTERFACE

(2.5V £ VDD £ 5.5V, TA = -20°C to +85°C.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

STANDARD BUS TIMING

Time Slot t

Recovery Time t

Write-0 Low Time t

Write-1 Low Time t

Read-Data Valid t

Reset-Time High t

Reset-Time Low t

Presence-Detect High t

Presence-Detect Low t

OVERDRIVE BUS TIMING

Time Slot t

Recovery Time t

Write-0 Low Time t

Write-1 Low Time t

60 120

SLOT

1

REC

60 120

LOW0

1 15

LOW1

15

RDV

480

RSTH

480 960

RSTL

15 60

PDH

60 240

PDL

6 16

SLOT

1

REC

6 16

LOW0

1 2

LOW1

ms

Read-Data Valid t

Reset-Time High t

Reset-Time Low t

Presence-Detect High t

Presence-Detect Low t

2

RDV

48

RSTH

48 80

RSTL

2 6

PDH

8 24

PDL

ms

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AC ELECTRICAL CHARACTERISTICS

(2.5V £ VDD £ 5.5V, TA = -20°C to +85°C.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DS2705: SHA-1 Authentication Master

Programming Pulse Width t

Programming Pulse Rise Time t

Programming Pulse Fall Time t

Strong Pullup Delay Time t

Strong Pullup Period t

Challenge Delay Time t

Authentication Attempt Time t

FAIL Pin Pulse Frequency

17 ms

PPW

(Note 8) 0.5 5

PPR

(Note 8) 0.5 5

PPF

2 10

SPUD

24 34 48 ms

SPUP

45 65 85 ms

CHD

(Note 9) 61 490 ms

AAT

FOM = 1, 50% duty cycle 1.5 2 2.5 Hz

t

FPF

Note 1:

Note 2:

Note 3:

Note 4:

Note 5:

Note 6:

Note 7:

Note 8:

Note 9:

Note 10:

All voltages are referenced to V

IDD3 Sleep mode conditions:

CHAL pin inactive OR (CHAL active AND (PAA = 0 AND PPT = 00 AND FOM = 0 AND Initial Authentication sequence complete))

[Above conditions disable the internal oscillator]

Programming temperature range is T

5 years data retention at 70°C

If CHAL pin left unconnected, CHP bit = 0 required for an authentication attempt to be initiated on power up. See Table 1.

Typical Communication mode MDQ pullup behavior equivalent to 3kW resistor.

Typical Computation mode MDQ pullup behavior approximates a 50W resistor.

Exceeding maximum rise and fall time specifications may affect device reliability.

t

= Retries per Attempt x (264bits x 90ms + 3 x (t

AAT

MAX[7 retries]: 490ms, MIN[no retries]: 61ms with standard timings

1. 1-Wire Master timings based on ±25% clock tolerance from nominal.

2. t

3. t

4. Bus rise time of ~1ms required to settle to logic high by t

[defined in design documentation] = t

RPDT

= t

MPDL-MAX

MRSTH-MIN

.

SS

– t

MPDH-MAX,

= 0°C to 50°C.

A

+ t

RSTH

MRSTH

) + t

MRSTL

represents the maximum presence pulse low time allowed from the slave.

) = [1 to 8] x (23.7ms + 3.54ms + 34ms)

SPUD

after MDQ released at t

MRDV

MLOW1

PIN DESCRIPTION

mMAX

TDFN

1 1 CHAL Challenge Strobe Input Pin. Initiates authentication. Active level/edge set by CHP bit.

2 2

3 3

4 4

5 5

6 6 SDQ

7 7 MDQ

8 8

SYMBOL FUNCTION

PASS

FAIL

V

SS

V

PP

Authentication “PASS” Result Open-Drain Output Pin

Authentication “FAIL” Result Open-Drain Output Pin (Programmable As Low Or Pulse)

Supply Return Pin, GND Reference for Logic Signals

EEPROM Programming Voltage Input

Slave Serial interface Data I/O Pin. Bidirectional data transmit and receive at 16kbps or 143kbps. Bus master must provide a weak pullup.

Master Serial interface Data I/O Pin. Bidirectional data transmit and receive at 16kbps or 143kbps. Provides a weak pullup in communication mode and strong pullup in computation mode.

V

Supply Input Pin. Bypass to VSS with 0.1mF capacitor.

DD

ms

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Figure 1. Block Diagram

DS2705: SHA-1 Authentication Master

VDD

EEPROM

64-bit

Challenge

CHP = 0

160-bit MAC

16-bit

Configuration

Pullup

Control

CHAL

PASS

FAIL

Control FSM

t

+ t

CHD

AAT

VSS

1-Wire

Master /

Slave

MDQ

SDQ

DETAILED DESCRIPTION

The DS2705 orchestrates a challenge/response SHA-1 authentication procedure by accessing a Dallas Battery Management SHA-1 Token product, such as the DS2703 or DS2704. The remote SHA-1 token is accessed with the MDQ pin acting as the 1-Wire bus master. The DS2705 issues the appropriate 1-Wire command sequence on MDQ to write the 64-bit challenge, initiates a SHA-1 computation in the token, and then reads back the 160-bit MAC result. The DS2705 compares the 160-bit MAC received from the battery token with the preprogrammed MAC. An exact bit for bit match is required for the authentication to be successful. The result of the operation, PASS or FAIL, is indicated on active low status output pins which can be used to drive status LEDs and/or enable cell charging.

The DS2705 can be configured to automatically authenticate by detection of a presence pulse on MDQ or authentication can be controlled by the state of the CHAL input pin. The DS2705’s SDQ pin is a 1-Wire slave interface for programming the behavior of the I.C.. All EEPROM values can be permanently locked to prevent corruption.

Figure 2 shows a example application circuit for a standalone battery charger. The DS2705 is preprogrammed for automatic authentication on MDQ and also contains a known good challenge/response pair. Programming occurs during assembly through PCB test points shown on the right side of the circuit. When a battery pack is inserted into the charger, a presence pulse on MDQ will cause the DS2705 to automatically authenticate the pack. The result of the authentication will be displayed through the LEDs and the DS2705 will either enable or disable the charging circuit.

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