DS4402N+TR MAXIM [Maxim Integrated Products], DS4402N+TR Datasheet - Page 5

• Manufacturer Part Number: DS4402N+TR
• Description: Two/Four-Channel, I2C Adjustable Current DAC
• Manufacturer: MAXIM [Maxim Integrated Products]

The DS4402/DS4404 contain two/four I
current sources (Figure 1) that are each capable of
sinking and sourcing current. Each output has 31 sink
and 31 source settings that are programmed through
the I
sponding step sizes) of the outputs are determined by
external resistors that adjust the output currents over a
4:1 range. The formula to determine the external resis-
tor values (R
Equation 1:
where I
On power-up, the DS4402/DS4404 output zero current.
This is done to prevent it from sinking or sourcing an
incorrect current before the system host controller has
had a chance to modify the device’s setting.
As a source for biasing instrumentation or other cir-
cuits, the DS4402/DS4404 provide a simple and inex-
pensive current source with an I
The adjustable full-scale range allows the application to
get the most out of its 5-bit sink or source resolution.
When used in adjustable power-supply applications
(see the Typical Operating Circuit ), the DS4402/DS4404
do not affect the initial power-up supply voltage because
it defaults to providing zero output current on power-up.
As it sources or sinks current into the feedback voltage
node, it changes the amount of output voltage required
by the regulator to reach its steady state operating point.
By using the external resistor to set the output current
range, the devices provide flexibility for adjusting the
impedances of the feedback network or the range over
which the power supply can be controlled or margined.
The DS4402/DS4404 respond to one of nine I
addresses determined by the two tri-level address
inputs. The three input states are connected to V
connected to ground, or disconnected. To sense the
disconnected state (Figure 2), the address inputs have
weak internal resistors that pull the pins to mid-supply.
Two/Four-Channel, I
2
C interface. The full-scale ranges (and corre-
FS
= desired full-scale current
FS
R
) for each of the outputs is given by:
FS
= (V
Detailed Description
REF
/ I
FS
) x (31 / 4)
2
I
2
C interface for control.
C Slave Address
_____________________________________________________________________
2
C adjustable
2
C slave
2
CC
C Adjustable Current DAC
,
Table 1. Slave Addresses
Table 1 lists the slave address determined by the
address input combinations.
Figure 2. I
GND
GND
GND
N.C.
N.C.
N.C.
V
V
V
A1
CC
CC
CC
2
C Address Inputs
A1
A0
GND
GND
GND
N.C.
N.C.
N.C.
V
V
V
A0
CC
CC
CC
R
R
IN
IN
V
CC
R
R
IN
IN
SLAVE ADDRESS
(HEXADECIMAL)
ADDRESS
DECODE
I
9Ch
9Ah
9Eh
A0h
90h
92h
94h
96h
98h
2
C
5