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_______________________________________________________________Maxim Integrated Products 1
General Description
The DS4422 and DS4424 contain two or four I 2C pro-grammable current DACs that are each capable of sinking and sourcing current up to 200µA. Each DAC output has 127 sink and 127 source ttings that are programmed using the I 2C interface. The current DAC outputs power up in a high-impedance state.
Applications
Power-Supply Adjustment Power-Supply Margining
Adjustable Current Sink or Source
Features
♦Two (DS4422) or Four (DS4424) Current DACs
♦Full-Scale Current 50µA to 200µA
hardlyever♦Full-Scale Range for Each DAC Determined by External Resistors ♦127 Settings Each for Sink and Source Modes ♦I 2C-Compatible Serial Interface
♦Two Address Pins Allow Four Devices on Same I 2C Bus ♦Low Cost
♦Small Package (14-Pin, 3mm x 3mm TDFN)♦-40°C to +85°C Temperature Range ♦2.7V to 5.5V Operating Range
DS4422/DS4424
Two-/Four-Channel, I 2C, 7-Bit Sink/Source
第一次爱的人英文版
Current DAC
Typical Operating Circuit
Ordering Information
Rev 0; 3/08
+Denotes a lead-free package.T&R = Tape and reel.
Pin Configuration appears at end of data sheet.
D S 4422/D S 4424
Two-/Four-Channel, I 2C, 7-Bit Sink/Source Current DAC
ABSOLUTE MAXIMUM RATINGS
RECOMMENDED OPERATING CONDITIONS
Stress beyond tho listed under “Absolute Maximum Ratings” may cau permanent damage to the device. The are stress ratings only, and functional operation of the device at the or any other conditions beyond tho indicated in the operational ctions of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Voltage Range on V CC , SDA, and SCL
Relative -0.5V to +6.0V Voltage Range on A0, A1, FS0, FS1, FS2, FS3, OUT0, OUT1, OUT2, and OUT3 Relative to
<.-0.5V to (V CC + 0.5V) (Not to exceed 6.0V.)
Operating Temperature Range ...........................-40°C to +85°C Storage -55°C to +125°C Refer to the IPC/JEDEC
J-STD-020 Specification.
DC ELECTRICAL CHARACTERISTICS
OUTPUT CURRENT SOURCE CHARACTERISTICS
DS4422/DS4424
Two-/Four-Channel, I 2C, 7-Bit Sink/Source
Current DAC
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FS Note 3:
Supply current specified with all outputs t to zero current tting. A0 and A1 are connected to GND. SDA and SCL are con-nected to V CC . Excludes current through R FS resistors (I RFS ). Total current including I RFS is I CC + (2 x I RFS ).
Note 4:The output-voltage range must be satisfied to ensure the device meets its accuracy and linearity specifications.Note 5:Temperature drift excludes drift caud by external resistor.
artist是什么意思Note 6:Differential linearity is defined as the difference between the expected incremental current increa with respect to position
and the actual increa. The expected incremental increa is the full-scale range divided by 127.
Note 7:Guaranteed by design.
Note 8:Integral linearity is defined as the difference between the expected value as a function of the tting and the actual value.
The expected value is a straight line between the zero and the full-scale values proportional to the tting.
Note 9:Timing shown is for fast-mode (400kHz) operation. This device is also backward compatible with I 2C standard-mode timing.Note 10:C B —total capacitance of one bus line in pF.
OUTPUT CURRENT SOURCE CHARACTERISTICS (continued)
AC ELECTRICAL CHARACTERISTICS
D S 4422/D S 4424
Two-/Four-Channel, I 2C, 7-Bit Sink/Source Current DAC 4_______________________________________________________________________________________
Typical Operating Characteristics
(T A = +25°C, unless otherwi noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
SUPPLY VOLTAGE (V)
S U P P L Y C U R R E N T (μA )
5.0
4.5
4.0
3.5
3.0
50100
150********.5
5.5
SUPPLY CURRENT vs. TEMPERATURE
TEMPERATURE (°C)
S U P P L Y C U R R E N T (μA )
80
60
40
20
-20
50
100
150
200250
-40
VOLTCO (SOURCE)
V OUT (V)
I O U T (μA )
4.54.03.5
3.02.52.01.51.00.5-225
-200
-
175-150
-250
5.0
VOLTCO (SINK)
V OUT (V)
I O U T (μA )
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3.5
3.0
2.5
2.01.5
英语4级作文范文1.0
0.5
macropus175
200
225250
150
4.0
TEMPERATURE COEFFICIENT vs. SETTING (SOURCE)
SETTING (DEC)T E M P E R A T U R E C O E F F I C I E N T (°C /p p m )
125
100755025-50050100150200-100
0TEMPERATURE COEFFICIENT
tennevs. SETTING (SINK)
SETTING (DEC)
T E M P E R A T U R E C O E F F I C I E N T (°C /p p m )怎么回答问题
125
100
75
50
25
-200-150
高考英语作文出炉
-100-50050
-250
INTEGRAL LINEARITY
SETTING (DEC)I N L (L S B )
125100
25
50
75
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-0.75-0.50-0.2500.250.500.751.00-1.00
DIFFERENTIAL LINEARITY
SETTING (DEC)
D N L (L S B )
125
100755025-0.8-0.6-0.4-0.200.20.40.60.81.0
-1.0
DS4422/DS4424
Two-/Four-Channel, I 2C, 7-Bit Sink/Source
Current DAC
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D S 4422/D S 4424
Two-/Four-Channel, I 2C, 7-Bit Sink/Source Current DAC 6_______________________________________________________________________________________
Detailed Description
The DS4422/DS4424 contain two or four I 2C adjustable current sources that are each capable of sinking and sourcing current. Each output (OUT0, OUT1, OUT2, and OUT3) has 127 sink and 127 source ttings that can be controlled by the I 2C interface. The full-scale ranges and corresponding
step sizes of the outputs are deter-mined by external resistors, connected to pins FS0, FS1,FS2, and FS3, that can adjust the output current over a 4:1 range. Pins OUT2, OUT3, FS2, and FS3 are only available on the DS4424.
The formula to determine R FS (connected to the FSx pins) to attain the desired full-scale current range is: Equation 1:
Where I FS is the desired full-scale current value, V RFS is the R FS voltage (e the DC Electrical Characteristics table), and R FS is the external resistor value.
To calculate the output current value (I OUT ) bad on the corresponding DAC value (e Table 1 for corresponding memory address), u equation 2.Equation 2:
On power-up the DS4422/DS4424 output zero current.This is done to prevent them from sinking or sourcing an incorrect amount of current before the system host con-troller has had a chance to modify the device’s tting.As a source for biasing instrumentation or other circuits,the DS4422/DS4424 provide a simple and inexpensive current source with an I 2C interface for control. The adjustable full-scale range allows the application to get the most out of its 7-bit sink or source resolution.
When ud in adjustable power-supply applications (e Typical Operating Circuit ), the DS4422/DS4424 do not affect the initial power-up voltage of the supply becau they default to providing zero output current on power-up. As the devices source or sink current into the feedback-voltage node, they change the amount of out-put voltage required by the regulator to reach its steady-state operating point. Using the external resistor, R FS , to t the output current range, the DS4422/DS4424 pro-vide some flexibility for adjusting the impedances of the feedback network or the range over which the power supply can be controlled or margined.
I 2C Slave Address
The DS4422/DS4424 respond to one of four I 2C slave address determined by the two address inputs, A0and A1. The address inputs should be connected to either V CC or ground. Table 1 lists the slave address determined by the address input combinations.
Memory Organization
To control the DS4422/DS4424’s current sources, write to the memory address listed in Table 2.
The format of each output control register is given by:
