DS1961S-F3 Maxim Integrated Products, DS1961S-F3 Datasheet - Page 30

• Manufacturer Part Number: DS1961S-F3
• Description: IBUTTON EEPROM 1KBit SHA-1 2CAN
• Manufacturer: Maxim Integrated Products
• Series: iButton®r

Specifications of DS1961S-F3

• Rohs Information: IButton RoHS Compliance Plan
• Memory Size: 128B
• Memory Type: EEPROM
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

1-WIRE SIGNALING
The DS1961S requires strict protocols to ensure data integrity. The protocol consists of four types of
signaling on one line: reset sequence with reset pulse and presence pulse, write 0, write 1, and read data.
Except for the presence pulse the bus master initiates all of these signals. The DS1961S can communicate
at two different speeds: standard speed and overdrive speed. If not explicitly set into the overdrive mode,
the DS1961S communicates at standard speed. While in overdrive mode the fast timing applies to all
waveforms.
To get from idle to active, the voltage on the 1-Wire line needs to fall from V
To get from active to idle, the voltage needs to rise from V
V
The initialization sequence required to begin any communication with the DS1961S is shown in Figure
10. A reset pulse followed by a presence pulse indicates the DS1961S is ready to receive data, given the
correct ROM and memory function command. In a mixed population network, the reset low time t
needs to be long enough for the slowest 1-Wire slave device to recognize it as a reset pulse. The duration
of t
Characteristics). If the bus master uses slew-rate control on the falling edge, it must pull down the line for
t
will return the device to standard speed. For the DS1961S to remain in overdrive mode, t
exceed the maximum value specified for overdrive speed.
Figure 10. INITIALIZATION PROCEDURE (RESET AND PRESENCE PULSES)
After the bus master has released the line it goes into receive mode (RX). Now the 1-Wire bus is pulled to
V
V
t
The t
expired, the DS1961S is ready for data communication. In a mixed population network, t
extended to minimum 480µs at standard speed and 48µs at overdrive speed to accommodate other 1-Wire
devices.
RSTL
PDL
ILMAX
PUP
TH
. To detect a presence pulse, the master must test the logical state of the 1-Wire line at t
RSTL
is crossed, the DS1961S waits for t
RSTH
+ t
through the pullup resistor or, in case of a DS2480B driver, by active circuitry. When the threshold
is relevant for the DS1961S when determining a logical level, but not for triggering any events.
F
to compensate for the edge. If the DS1961S is in overdrive mode, a standard speed reset pulse
depends on the communication speed and the 1-Wire pull-up voltage (see Electrical
V
window must be at least the sum of t
IHMASTER
V
V
ILMAX
V
V
PUP
0V
TH
TL
t
F
RESISTOR
MASTER TX RESET PULSE
t
RSTL
PDH
and then transmits a presence pulse by pulling the line low for
PDHMAX
30 of 36
MASTER
MASTER RX PRESENCE PULSE
e
, t
PDLMAX
t
PDH
ILMAX
t
MSP
, and t
t
PDL
past the threshold V
t
RSTH
RECMIN
PUP
DS1961S
. Immediately after t
t
REC
below the threshold V
TH
MSP
RSTH
. The voltage
RSTL
.
should be
must not
RSTH
RSTL
TL
is
.