DS4426T+TR MAXIM [Maxim Integrated Products], DS4426T+TR Datasheet - Page 6

• Manufacturer Part Number: DS4426T+TR
• Description: Quad-Channel, I2C-Margining IDACs with Three Channels of Power-Supply Tracking
• Manufacturer: MAXIM [Maxim Integrated Products]

Quad-Channel, I
Three Channels of Power-Supply Tracking
The DS4426 contains four I
sources that are each capable of sinking and sourcing
current. Three of the current outputs (OUT[3:1]) also
have power-supply tracking circuitry that allows addi-
tional current to be sourced during power-up.
Each output (OUT[3:0]) has 127 sink and 127 source
settings that are programmed through the I
The full-scale current ranges (and corresponding step
sizes) of the outputs are determined by external resis-
tors connected to the corresponding FS pins (see
Figure 1). The formula to determine the external resistor
values (R
where I
the R
table), and R
6
_______________________________________________________________________________________
FS
11, 13, 15
12, 14, 16
17, 19, 20
25, 26, 27
FS
5, 6, 7
21–24
PIN
voltage (see the DC Electrical Characteristics
10
18
28
—
FS
1
2
3
4
8
9
is the desired full-scale current value, V
) for each output is given by:
FS
is the external resistor value.
R
FS
OUT1, OUT2, OUT3
THR3, THR2, THR1
FS0, FS1, FS2, FS3
=
Detailed Description
INN1, INN2, INN3
INP1, INP2, INP3
Adjustable Current DACs
GAIN3, GAIN2,
16
V
RFS
×
NAME
GAIN1
OUT0
GND
DNC
SDA
N.C.
SCL
V
I
A0
A1
EP
FS
CC
2
C-adjustable current
×
127
2
C-Margining IDACs with
Serial Data Input/Output. I
Serial Clock Input. I
Voltage Supply
Current DAC Output
Current DAC and Tracking Control Output
Ground
I
I
Power-Supply Tracking Positive Input
Power-Supply Tracking Negative Input
Threshold Input. Comparator input used to set threshold for tracking
enable/disable based on V
Do Not Connect
Full-Scale Calibration Input. A resistor-to-ground on this input determines full-
scale output current on the associated output.
Gain Adjustment Pin. Connect a resistor between this pin and V
No Connection
Exposed Pad. No connection.
2
2
2
C Address Input 0
C Address Input 1
C interface.
RFS
is
2
C clock input.
To calculate the output-current value (I
corresponding DAC value (see Table 2 for correspond-
ing memory addresses), use the following equation:
On power-up, the DS4426 current DAC outputs are set
to zero current. This is done to prevent the device from
sinking or sourcing an incorrect current before the sys-
tem host controller has a chance to modify its setting.
Note, however, that if power-supply tracking is enabled
(see the Power-Supply Tracking Circuit section), then
the DS4426 can still source current at power-up.
When used in adjustable power-supply applications
(see Figure 8), the DS4426 does not affect the initial
power-up voltage of the supply because it defaults to
providing zero output current on power-up unless
power-supply tracking is enabled. 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.
2
C data pin.
REF
/2.
FUNCTION
I
OUT
=
DACValue dec
127
Pin Description
(
)
OUT
×
CC
I
FS
.
) based on the