DS2703 Dallas Semiconductor, DS2703 Datasheet - Page 19

• Manufacturer Part Number: DS2703
• Description: SHA-1 Battery Pack Authentication IC
• Manufacturer: Dallas Semiconductor

COMPUTATION AND PROGRAMMING
The Compute Next Secret operation waveform is shown in Figure 11. The user issues a 1-Wire reset followed by a
Skip ROMID command, Match ROMID plus the ROMID, Search or Read Net, followed by the Compute Next Secret
command. The system host must connect the low impedance source to the DQ line within time t
of time t
rise and fall time requirements for the programming pulse are required to prevent damage during the transition
between normal communication mode and programming mode.
Figure 11. Compute Next Secret Function Command
1-Wire
Reset
Presence
Pulse
SHA
. The DQ line is then pulled to V
SKIP ROM
Cmd
Next Secret
Compute
Cmd
t
D
PP
for t
Impedance
Apply Low
Pull-up
PPW
t
SHA
19 of 20
milliseconds and then returned to nominal voltage. The fast
t
PPR
Programming
Apply
Pulse
t
PPW
D
and for a duration
t
PPF