DS1922E-F5# Maxim Integrated Products, DS1922E-F5# Datasheet - Page 18

• Manufacturer Part Number: DS1922E-F5#
• Description: IBUTTON TEMP LOGGER 4KBit F5
• Manufacturer: Maxim Integrated Products
• Series: iButton®r

Specifications of DS1922E-F5#

• Rohs Information: IButton RoHS Compliance Plan
• Memory Size: 512B
• Memory Type: NVSRAM (Non-Volatile SRAM)
• Lead Free Status / RoHS Status: Lead free by exemption / RoHS compliant by exemption

The Device Samples Counter register is similar to the
Mission Samples Counter register. During a mission this
counter increments whenever the DS1922E wakes up
to measure and log data and when the device is testing
for a temperature alarm in SUTA mode. Between mis-
sions the counter increments whenever the Forced
Conversion command is executed. This way the Device
Samples Counter register functions like a gas gauge for
the battery that powers the iButton.
The Device Samples Counter register is reset to zero
when the iButton is assembled. The counter increments
a couple of times during final test. The number format is
24-bit unsigned integer. The maximum number that can
be represented in this format is 16,777,215.
The code in the Device Configuration register allows
the master to distinguish between the DS2422 chip and
different versions of the DS1922 iButtons. The Device
Configuration Register table shows the codes assigned
to the various devices.
High-Temperature Logger iButton with 8KB
Data-Log Memory
Note: There is only read access to this register.
Note: There is only read access to this register.
Note: During a mission, there is only read access to this register.
18
ADDRESS
ADDRESS
ADDRESS
0226h
0223h
0224h
0225h
0227h
______________________________________________________________________________________
BIT 7
BIT 7
BIT 7
0
0
0
0
1
BIT 6
0
0
1
1
0
BIT 6
BIT 6
Other Indicators
BIT 5
0
1
0
1
0
BIT 5
BIT 5
BIT 4
0
0
0
0
0
BIT 4
BIT 4
Center Byte
High Byte
Low Byte
The DS1922E is designed to use two passwords that
control read access and full access. Reading from or
writing to the scratchpad as well as the forced conver-
sion command does not require a password. The pass-
word must be transmitted immediately after the
command code of the memory or control function. If
password checking is enabled, the password transmit-
ted is compared to the passwords stored in the device.
The data pattern stored in the Password Control regis-
ter determines whether password checking is enabled.
To enable password checking, the EPW bits need to
form a binary pattern of 10101010 (AAh). The default
pattern of EPW is different from AAh. If the EPW pattern
is different from AAh, any pattern is accepted as long
as it has a length of exactly 64 bits. Once enabled,
changing the passwords and disabling password
checking requires the knowledge of the current full-
access password.
BIT 3
EPW
0
0
0
0
0
BIT 3
BIT 3
Device Samples Counter Register
BIT 2
0
0
0
0
0
Device Configuration Register
Password Control Register
BIT 2
BIT 2
BIT 1
0
0
0
0
0
Security by Password
BIT 1
BIT 1
BIT 0
0
0
0
0
0
DS1922L
DS1922T
DS1922E
DS2422
DS1923
BIT 0
BIT 0
PART