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DS1621
Digital Thermometer and Thermostat
FEATURES
§ Temperature measurements require no
external components
§ Measures temperatures from -55°C to +125°C
in 0.5°C increments. Fahrenheit equivalent is
-67°F to 257°F in 0.9°F increments
§ Temperature is read as a 9-bit value (2-byte
transfer)
§ Wide power supply range (2.7V to 5.5V)
§ Converts temperature to digital word in less
than 1 second
§ Thermostatic settings are user definable and
nonvolatile
§ Data is read from/written via a 2-wire serial
interface (open drain I/O lines)
§ Applications include thermostatic controls,
industrial systems, consumer products,
thermometers, or any thermal sensitive
system
§ 8-pin DIP or SO package (150mil and
208mil)
PIN ASSIGNMENT
SD
1
SCL
T
OUT
GND
SD
SCL
T
GND
DS1621 8-PIN DIP (300mil)
3
DS1621S 8-PIN SO (150mil)
DS1621V 8-PIN SO (208mil)
1
3
7
6
PIN DESCRIPTION
7
6
V
DD
0
1
A
2
V
DD
0
1
A
2
SDA - 2-Wire Serial Data Input/Output
SCL - 2-Wire Serial Clock
GND - Ground
T
- Thermostat Output Signal
OUT
A0 - Chip Address Input
A1 - Chip Address Input
A2 - Chip Address Input
VDD - Power Supply Voltage
DESCRIPTION
The DS1621 Digital Thermometer and Thermostat provides 9-bit temperature readings, which indicate
the temperature of the device. The thermal alarm output, T
device exceeds a user-defined temperature TH. The output remains active until the temperature drops
below user defined temperature TL, allowing for any hysteresis necessary.
User-defined temperature settings are stored in nonvolatile memory so parts may be programmed prior to
insertion in a system. Temperature settings and temperature readings are all communicated to/from the
DS1621 over a simple 2-wire serial interface.
, is active when the temperature of the
OUT
1 of 16 090905
DS1621
ORDERING INFORMATION
ORDERING
NUMBER
DS1621 DS1621 DS1621 in 300 mil DIP
DS1621+ DS1621 (See Note) DS1621 in Lead-Free 300 mil DIP
DS1621S DS1621 DS1621 in 150 mil SOIC
DS1621S+ DS1621 (See Note) DS1621 in Lead-Free 150 mil SOIC
DS1621S/T&R DS1621 DS1621 in 150 mil SO, 2500 Piece Tape-and-Reel
DS1621S+T&R DS1621 (See Note) DS1621 in Lead-Free 150 mil SO, 2500 Piece Tape-and-Reel
DS1621V DS1621V DS1621 in 208 mil SOIC
DS1621V+ DS1621V (See Note) DS1621 in Lead-Free 208 mil SOIC
DS1621V/T&R DS1621V DS1621 in 208 mil SO, 2500 Piece Tape-and-Reel
DS1621V+T&R DS1621V (See Note) DS1621 in Lead-Free 208 mil SO, 2500 Piece Tape-and-Reel
Note: A “+” symbol will also be marked on the package near the Pin 1 indicator.
PACKAGE
MARKING
DESCRIPTION
Table 1. DETAILED PIN DESCRIPTION
PIN SYMBOL DESCRIPTION
1 SDA Data input/output pin for 2-wire serial communication port.
2 SCL Clock input/output pin for 2-wire serial communication port.
3 T
Thermostat output. Active when temperature exceeds TH; will reset when
OUT
temperature falls below TL.
4 GND Ground pin.
5 A2 Address input pin.
6 A1 Address input pin.
7 A0 Address input pin.
8 VDD Supply voltage input power pin. (2.7V to 5.5V)
OPERATION
Measuring Temperature
A block diagram of the DS1621 is shown in Figure 1.
The DS1621 measures temperature using a bandgap-based temperature sensor. A delta-sigma analog-todigital converter (ADC) converts the measured temperature to a digital value that is calibrated in °C; for
°F applications, a lookup table or conversion routine must be used.
The temperature reading is provided in a 9-bit, two’s complement reading by issuing the READ
TEMPERATURE command. Table 2 describes the exact relationship of output data to measured
temperature. The data is transmitted through the 2-wire serial interface, MSB first. The DS1621 can
measure temperature over the range of -55°C to +125°C in 0.5°C increments.
2 of 16
Figure 1. DS1621 FUNCTIONAL BLOCK DIAGRAM
A
SCL
SD
A0
A1
A2
ADDRESS
AND
I/O CONTROL
STATUS REGISTER &
CONTROL LOGIC
TEMPERATURE SENSOR
HIGH TEMP TRIGGER, TH
LOW TEMP TRIGGER, TL
DIGITAL COMPARATOR/LOGIC
DS1621
T
OUT
3 of 16
DS1621
Table 2. TEMPERATURE/DATA RELATIONSHIPS
TEMPERATURE DIGITAL OUTPUT
(Binary)
+125°C 01111101 00000000 7D00h
+25°C 00011001 00000000 1900h
+½°C 00000000 10000000 0080h
+0°C 00000000 00000000 0000h
-½°C 11111111 10000000 FF80h
-25°C 11100111 00000000 E700h
-55°C 11001001 00000000 C900h
Since data is transmitted over the 2-wire bus MSB first, temperature data may be written to/read from the
DS1621 as either a single byte (with temperature resolution of 1°C) or as two bytes. The second byte
would contain the value of the least significant (0.5°C) bit of the temperature reading as shown in Table
1. Note that the remaining 7 bits of this byte are set to all "0"s.
Temperature is represented in the DS1621 in terms of a ½°C LSB, yielding the following 9-bit format:
DIGITAL OUTPUT
(Hex)
Figure 2. TEMPERATURE, TH, and TL FORMAT
MSB LSB
1
1 1 0 0
Higher resolutions may be obtained by reading the temperature and truncating the 0.5°C bit (the LSB)
from the read value. This value is TEMP_READ. A Read Counter command should be issued to yield the
COUNT_REMAIN value. The Read Slope command should then be issued to obtain the
COUNT_PER_C value. The higher resolution temperature may be then be calculated by the user using
the following:
TEMPERATURE=TEMP_READ-0.25 +
The DS1621 always powers up in a low power idle state, and the Start Convert T command must be used
to initiate conversions.
The DS1621 can be programmed to perform continuous consecutive conversions (continuous-conversion
mode) or to perform single conversions on command (one-shot mode). The conversion mode is
programmed through the 1SHOT bit in the configuration register as explained in the Operation and
Control section of this datasheet. In continuous conversion mode, the DS1621 begins continuous
conversions after a Start Convert T command is issued. Consecutive conversions continue to be
performed until a Stop Convert T command is issued, at which time the device goes into a low-power idle
state. Continuous conversions can be restarted at any time using the Start Convert T command.
1
1 1
0
0 0 0 0
0
0 0
T = -25°C
REMAINCOUNTCPERCOUNT
CPERCOUNT
__
)___( -
4 of 16
DS1621
(°C)
In one-shot mode, the DS1621 performs a single temperature conversion when a Start Convert T
command is issued. When the conversion is complete, the device enters a low-power idle state and
remains in that state until a single temperature conversion is again initiated by a Start Convert T
command.
Thermostat Control
In its operating mode, the DS1621 functions as a thermostat with programmable hysteresis as shown in
Figure 3. The thermostat output updates as soon as a temperature conversion is complete.
When the DS1621’s temperature meets or exceeds the value stored in the high temperature trip register
(TH), the output becomes active and will stay active until the temperature falls below the temperature
stored in the low temperature trigger register (TL). In this way, any amount of hysteresis may be
obtained.
The active state for the output is programmable by the user so that an active state may either be a logic
"1" (V
) or a logic "0" (0V). This is done using the POL bit in the configuration reagister as explained
DD
in the Operation and Control section of this datasheet.
Figure 3. THERMOSTAT OUTPUT OPERATION
DQ (Thermostat output, Active = High)
TL TH T
OPERATION AND CONTROL
The DS1621 must have temperature settings resident in the TH and TL registers for thermostatic
operation. A configuration/status register also determines the method of operation that the DS1621 will
use in a particular application, as well as indicating the status of the temperature conversion operation.
The configuration register is defined as follows:
MSb Bit 6 Bit5 Bit 4 Bit 3 Bit 2 Bit 1 LSb
DONE THF TLF NVB X X POL 1SHOT
where
DONE = Conversion Done bit. “1” = Conversion complete, “0” = Conversion in progress.
THF = Temperature High Flag. This bit will be set to “1” when the temperature is greater than or
equal to the value of TH. It will remain “1” until reset by writing “0” into this location or removing power
from the device. This feature provides a method of determining if the DS1621 has ever been subjected to
temperatures above TH while power has been applied.
5 of 16
DS1621
TLF = Temperature Low Flag. This bit will be set to “1” when the temperature is less than or equal
to the value of TL. It will remain “1” until reset by writing “0” into this location or removing power from
the device. This feature provides a method of determining if the DS1621 has ever been subjected to
temperatures below TL while power has been applied.
2
NVB = Nonvolatile Memory Busy flag. “1” = Write to an E
nonvolatile memory is not busy. A copy to E
2
may take up to 10 ms.
memory cell in progress, “0” =
POL = Output Polarity Bit. “1” = active high, “0” = active low. This bit is nonvolatile.
1SHOT = One Shot Mode. If 1SHOT is “1”, the DS1621 will perform one temperature conversion upon
receipt of the Start Convert T protocol. If 1SHOT is “0”, the DS1621 will continuously perform
temperature conversions. This bit is nonvolatile.
X = Reserved.
For typical thermostat operation the DS1621 will operate in continuous mode. However, for applications
where only one reading is needed at certain times or to conserve power, the one-shot mode may be used.
Note that the thermostat output (T
) will remain in the state it was in after the last valid temperature
OUT
conversion cycle when operating in one-shot mode.
2-WIRE SERIAL DATA BUS
The DS1621 supports a bidirectional 2-wire bus and data transmission protocol. A device that sends data
onto the bus is defined as a transmitter, and a device receiving data as a receiver. The device that controls
the message is called a “master." The devices that are controlled by the master are “slaves." The bus must
be controlled by a master device which generates the serial clock (SCL), controls the bus access, and
generates the START and STOP conditions. The DS1621 operates as a slave on the 2-wire bus.
Connections to the bus are made via the open-drain I/O lines SDA and SCL.
The following bus protocol has been defined (See Figure 4):
§ Data transfer may be initiated only when the bus is not busy.
§ During data transfer, the data line must remain stable whenever the clock line is HIGH. Changes in
the data line while the clock line is high will be interpreted as control signals.
Accordingly, the following bus conditions have been defined:
Bus not busy: Both data and clock lines remain HIGH.
Start data transfer: A change in the state of the data line, from HIGH to LOW, while the clock is HIGH,
defines a START condition.
Stop data transfer: A change in the state of the data line, from LOW to HIGH, while the clock line is
HIGH, defines the STOP condition.
Data valid: The state of the data line represents valid data when, after a START condition, the data line
is stable for the duration of the HIGH period of the clock signal. The data on the line must be changed
during the LOW period of the clock signal. There is one clock pulse per bit of data.
6 of 16
DS1621
Each data transfer is initiated with a START condition and terminated with a STOP condition. The
number of data bytes transferred between START and STOP conditions is not limited and is determined
by the master device. The information is transferred byte-wise and each receiver acknowledges with a
ninth-bit.
Within the bus specifications a regular mode (100kHz clock rate) and a fast mode (400kHz clock rate) are
defined. The DS1621 works in both modes.
Acknowledge: Each receiving device, when addressed, is obliged to generate an acknowledge after the
reception of each byte. The master device must generate an extra clock pulse which is associated with this
acknowledge bit.
A device that acknowledges must pull down the SDA line during the acknowledge clock pulse in such a
way that the SDA line is stable LOW during the HIGH period of the acknowledge related clock pulse. Of
course, setup and hold times must be taken into account. A master must signal an end of data to the slave
by not generating an acknowledge bit on the last byte that has been clocked out of the slave. In this case,
the slave must leave the data line HIGH to enable the master to generate the STOP condition.
Figure 4. DATA TRANSFER ON 2-WIRE SERIAL BUS
Figure 4 details how data transfer is accomplished on the 2-wire bus. Depending upon the state of the
R/W bit, two types of data transfer are possible:
1. Data transfer from a master transmitter to a slave receiver. The first byte transmitted by the
master is the slave address. Next follows a number of data bytes. The slave returns an acknowledge
bit after each received byte.
2. Data transfer from a slave transmitter to a master receiver. The first byte, the slave address, is
transmitted by the master. The slave then returns an acknowledge bit. Next follows a number of data
bytes transmitted by the slave to the master. The master returns an acknowledge bit after all received
bytes other than the last byte. At the end of the last received byte, a ‘not acknowledge’ is returned.
The master device generates all of the serial clock pulses and the START and STOP conditions. A
transfer is ended with a STOP condition or with a repeated START condition. Since a repeated START
condition is also the beginning of the next serial transfer, the bus will not be released.
7 of 16
DS1621
The DS1621 may operate in the following two modes:
1. Slave receiver mode: Serial data and clock are received through SDA and SCL. After each byte is
received an acknowledge bit is transmitted. START and STOP conditions are recognized as the
beginning and end of a serial transfer. Address recognition is performed by hardware after reception
of the slave address and direction bit.
2. Slave transmitter mode: The first byte is received and handled as in the slave receiver mode.
However, in this mode the direction bit will indicate that the transfer direction is reversed. Serial data
is transmitted on SDA by the DS1621 while the serial clock is input on SCL. START and STOP
conditions are recognized as the beginning and end of a serial transfer.
SLAVE ADDRESS
A control byte is the first byte received following the START condition from the master device. The
control byte consists of a 4-bit control code; for the DS1621, this is set as 1001 binary for read and write
operations. The next 3 bits of the control byte are the device select bits (A2, A1, A0). They are used by
the master device to select which of eight devices are to be accessed. These bits are in effect the 3 least
significant bits of the slave address. The last bit of the control byte (R/ W ) defines the operation to be
performed. When set to a “1” a read operation is selected, when set to a “0” a write operation is selected.
Following the START condition the DS1621 monitors the SDA bus checking the device type identifier
being transmitted. Upon receiving the 1001 code and appropriate device select bits, the slave device
outputs an acknowledge signal on the SDA line.
8 of 16
Figure 5. 2-WIRE SERIAL COMMUNICATION WITH DS1621
DS1621
9 of 16
DS1621
COMMAND SET
Data and control information is read from and written to the DS1621 in the format shown in Figure 5. To
write to the DS1621, the master will issue the slave address of the DS1621 and the R/ W bit will be set to
“0”. After receiving an acknowledge, the bus master provides a command protocol. After receiving this
protocol, the DS1621 will issue an acknowledge and then the master may send data to the DS1621. If the
DS1621 is to be read, the master must send the command protocol as before and then issue a repeated
START condition and the control byte again, this time with the R/ W bit set to “1” to allow reading of the
data from the DS1621. The command set for the DS1621 as shown in Table 3 is as follows:
Read Temperature [AAh]
This command reads the last temperature conversion result. The DS1621 will send 2 bytes, in the format
described earlier, which are the contents of this register.
Access TH [A1h]
If R/ W is “0” this command writes to the TH (HIGH TEMPERATURE) register. After issuing this
command, the next 2 bytes written to the DS1621, in the same format as described for reading
temperature, will set the high temperature threshold for operation of the T
output. If R/ W is “1” the
OUT
value stored in this register is read back.
Access TL [A2h]
If R/ W is “0” this command writes to the TL (LOW TEMPERATURE) register. After issuing this
command, the next 2 bytes written to the DS1621, in the same format as described for reading
temperature, will set the high temperature threshold for operation of the T
output. If R/ W is “1” the
OUT
value stored in this register is read back.
Access Config [ACh]
If R/ W is “0” this command writes to the configuration register. After issuing this command, the next
data byte is the value to be written into the configuration register. If R/ W is “1” the next data byte read is
the value stored in the configuration register.
Read Counter [A8h]
This command reads the value Count_Remain. This command is valid only if R/ W is “1”.
Read Slope [A9h]
This command reads the value Count_Per_C. This command is valid only if R/ W is “1”.
Start Convert T [EEh]
This command begins a temperature conversion. No further data is required. In one-shot mode the
temperature conversion will be performed and then the DS1621 will remain idle. In continuous mode this
command will initiate continuous conversions.
Stop Convert T [22h]
This command stops temperature conversion. No further data is required. This command may be used to
halt a DS1621 in continuous conversion mode. After issuing this command, the current temperature
measurement will be completed and the DS1621 will remain idle until a Start Convert T is issued to
resume continuous operation.
10 of 16
DS1621
Table 3. DS1621 COMMAND SET
INSTRUCTION
DESCRIPTION
TEMPERATURE CONVERSION COMMANDS
Read Temperature Read last converted temperature
value from temperature register.
Read Counter Reads value of Count_Remain A8h <read data>
Read Slope Reads value of the
Count_Per_C
Start Convert T Initiates temperature
conversion.
Stop Convert T Halts temperature conversion. 22h idle 1
Access TH Reads or writes high
temperature limit value into TH
register.
Access TL Reads or writes low
temperature limit value into TL
register.
Access Config Reads or writes configuration
data to configuration register.
PROTOCOL
AAh <read 2 bytes data>
A9h <read data>
EEh idle 1
THERMOSTAT COMMANDS
A1h <write data> 2
A2h <write data> 2
ACh <write data> 2
2-WIRE BUS DATA
AFTER ISSUING
PROTOCOL
NOTES
NOTES:
1. In continuous conversion mode a Stop Convert T command will halt continuous conversion. To
restart the Start Convert T command must be issued. In one-shot mode a Start Convert T command
must be issued for every temperature reading desired.
2. Writing to the E
no further writes should be requested for at least 10ms.
2
requires a maximum of 10ms at room temperature. After issuing a write command,
11 of 16
MEMORY FUNCTION EXAMPLE
Example: Bus master sets up DS1621 for continuous conversion and thermostatic function.
BUS MASTER
MODE
TX RX START Bus Master initiates a START condition.
TX RX <address,0>
RX TX ACK DS1621 generates acknowledge bit.
TX RX ACh Bus Master sends Access Config command protocol.
RX TX ACK DS1621 generates acknowledge bit.
TX RX 02h Bus Master sets up DS1621 for output polarity active
RX TX ACK DS1621 generates acknowledge bit.
TX RX START Bus Master generates a repeated START condition.
TX RX <address,0>
RX TX ACK DS1621 generates acknowledge bit.
TX RX A1h Bus Master sends Access TH command.
RX TX ACK DS1621 generates acknowledge bit.
TX RX 28h Bus Master sends first byte of data for TH limit of
RX TX ACK DS1621 generates acknowledge bit.
TX RX 00h Bus Master sends second byte of data for TH limit of
RX TX ACK DS1621 generates acknowledge bit.
TX RX START Bus Master generates a repeated START condition.
TX RX <address,0>
RX TX ACK DS1621 generates acknowledge bit.
TX RX A2h Bus Master sends Access TL command.
RX TX ACK DS1621 generates acknowledge bit.
TX RX 0Ah Bus Master sends first byte of data for TL limit of
RX TX ACK DS1621 generates acknowledge bit.
TX RX 00h Bus Master sends second byte of data for TL limit of
RX TX ACK DS1621 generates acknowledge bit.
TX RX START Bus Master generates a repeated START condition.
TX RX <address,0>
RX TX ACK DS1621 generates acknowledge bit.
TX RX EEh Bus Master sends Start Convert T command protocol.
RX TX ACK DS1621 generates acknowledge bit.
TX RX STOP Bus Master initiates STOP condition.
DS1621
MODE
DATA (MSB
FIRST)
COMMENTS
Bus Master sends DS1621 address; R/ W = 0.
high, continuous conversion.
Bus Master sends DS1621 address; R/
W = 0.
+40°C.
+40°C.
Bus Master sends DS1621 address; R/ W = 0.
+10°C.
+10°C.
Bus Master sends DS1621 address; R/
W = 0.
DS1621
12 of 16
DS1621
ABSOLUTE MAXIMUM RATINGS*
Voltage on Any Pin Relative to Ground -0.5V to +6.0V
Operating Temperature Range -55°C to +125°C
Storage Temperature Range -55°C to +125°C
Soldering Temperature See IPC/JEDEC J-STD-020A Specification
* This is a stress rating only and functional operation of the device at these or any other conditions above
those indicated in the operation sections of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods of time may affect reliability.
RECOMMENDED DC OPERATING CONDITIONS
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Supply Voltage VDD 2.7 5.5 V 1
DC ELECTRICAL CHARACTERISTICS (-55°C to +125°C; V
PARAMETER SYMBOL CONDITION MIN TYP MAX UNITS NOTES
Thermometer Error T
0°C to 70°C
-55°C to +0°C
Thermometer
Resolution
Low Level Input
Voltage
High Level Input
Voltage
Pulse width of
spikes which must
be suppressed by
the input filter
Voltage
Input Current each
I/O Pin
I/O Capacitance C
0°C to 70°C
ERR
3.0V£VDD£5.5V
2.7V£VDD£3.0V
and
±½ °C
±1 °C
±2 °C
70°C to 125°C
12 bits
VIL 0.5 0.3 VDD V
VIH 0.7 V
tSP
V
3 mA Sink
OL1
Fast Mode
DD
0
0 0.4 V Low Level Output
VDD+0.3 V
50
Current
6 mA Sink
V
OL2
0 0.6 V
Current
0.4<V
10 pF
I/O
<0.9VDD -10 10 µA 2
I/O
= 2.7V to 5.5V)
DD
ns
13 of 16
Active Supply
Current
Standby Supply
Current
(T
) Output
OUT
Voltage
DS1621
ICC
Temperature
Conversion
-55°C to +85°C
Temperature
Conversion
+85°C to +125°C
2
Write
E
Communication
1000
1250
400
110
µA
3, 4
Only
I
1 µA 3, 4
STBY
VOH 1 mA Source 2.4 V Thermostat Output
VOL 4 mA Sink 0.4 V
14 of 16
DS1621
AC ELECTRICAL CHARACTERISTICS (-55°C to +125°C; V
= 2.7V to 5.5V)
DD
PARAMETER SYMBOL CONDITION MIN TYP MAX UNITS NOTES
Temperature
TTC 750 ms
Conversion Time
NV Write Cycle
tWR 0°C to 70°C 4 10 ms 10
Time
SCL Clock
Frequency
Bus Free Time
Between a STOP
f
Fast Mode
SCL
Standard Mode
t
Fast Mode
BUF
Standard Mode
0
0
1.3
4.7
400
KHz
100
µs
and START
Condition
Hold Time
(Repeated) START
t
HD:STA
Fast Mode
Standard Mode
0.6
4.0
µs 5
Condition
Low Period of SCL
Clock
High Period of SCL
Clock
Setup Time for a
Repeated START
T
Fast Mode
LOW
Standard Mode
T
Fast Mode
HIGH
Standard Mode
t
Fast Mode
SU:STA
Standard Mode
1.3
4.7
0.6
4.0
0.6
4.7
µs
µs
µs
Condition
Data Hold Time t
Data Setup Time t
Rise Time of Both
SDA and SCL
HD:DAT
Fast Mode
Standard Mode
Fast Mode
SU:DAT
Standard Mode
tR Fast Mode
Standard Mode
0
0
100
250
20+0.1C
0.9 µs 6, 7
ns 8
B
300
ns 9
1000
Signals
Fall Time of both
SDA and SCL
tF Fast Mode
20+0.1C
Standard Mode
B
300
ns 9
300
Signals
Setup time for
STOP Condition
Capacitative Load
t
Fast Mode
SU:STO
Standard Mode
0.6
4.0
µs
Cb 400 pF
for each Bus Line
All values referred to VIH=0.9 VDD and VIL=0.1 VDD.
AC ELECTRICAL CHARACTERISTICS (-55°C to +125°C; VDD = 2.7V to 5.5V)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Input Capacitance CI 5 pF
15 of 16
DS1621
NOTES:
1. All voltages are referenced to ground.
2. I/O pins of fast mode devices must not obstruct the SDA and SCL lines if V
is switched off.
DD
3. I
specified with T
CC
pin open.
OUT
4. I
specified with VCC at 5.0V and SDA, SCL = 5.0V, 0°C to 70°C.
CC
5. After this period, the first clock pulse is generated.
6. A device must internally provide a hold time of at least 300ns for the SDA signal (referred to the
V
of the SCL signal) in order to bridge the undefined region of the falling edge of SCL.
IH MIN
7. The maximum t
HD:DAT
has only to be met if the device does not stretch the LOW period (t
LOW
) of the
SCL signal.
8. A fast mode device can be used in a standard mode system, but the requirement t
>250ns must
SU:DAT
then be met. This will automatically be the case if the device does not stretch the LOW period of the
SCL signal. If such a device does stretch the LOW period of the SCL signal, it must output the next
data bit to the SDA line t
RMAX
+ t
SU:DAT
= 1000 + 250 = 1250ns before the SCL line is released.
9. C
—total capacitance of one bus line in pF.
B
10. Writing to the nonvolatile memory should only take place in the 0°C to 70°C temperature range.
TIMING DIAGRAM
16 of 16
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