DS4432U+ Maxim Integrated Products, DS4432U+ Datasheet - Page 6

• Manufacturer Part Number: DS4432U+
• Description: IC DAC 7BIT 2CH 5.5V 8-MSOP
• Manufacturer: Maxim Integrated Products

Specifications of DS4432U+

• Number Of Bits: 7
• Data Interface: I²C, Serial
• Number Of Converters: 2
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Number Of Dac Outputs: 2
• Resolution: 7 bit
• Interface Type: I2C
• Settling Time: 1.3 us
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 2.7 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Supply Current: 150 uA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power Dissipation (max): -
• Settling Time: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Dual-Channel, I
Current DAC
The DS4432 contains two I
that are each capable of sinking and sourcing current.
Each output (OUT0 and OUT1) has 127 sink and 127
source settings that can be controlled by the I
face. The full-scale ranges and corresponding step
sizes of the outputs are determined by external resis-
tors, connected to pins FS0 and FS1.
The formula to determine R
pins) to attain the desired full-scale current range is:
Equation 1:
where I
the R
table), and R
To calculate the output current value (I
corresponding DAC value (see Table 1 for corresponding
memory addresses), use equation 2.
Equation 2:
On power-up the DS4432 outputs zero current. This is
done to prevent the device from sinking or sourcing an
incorrect amount of current before the system host con-
troller has had a chance to modify the DS4432’s setting.
As a source for biasing instrumentation or other circuits,
the DS4432 provides a simple and inexpensive current
DAC with an I
full-scale range allows the application to get the most
out of its 7-bit sink or source resolution.
When used in adjustable power-supply applications
(see the Typical Operating Circuit ), the DS4432 does
not affect the initial power-up voltage of the supply
because it defaults to providing zero output current on
power-up. As the device 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. Using the external resistor,
R
vides some flexibility for adjusting the impedances of
the feedback network or the range over which the power
supply can be controlled or margined.
6
FS
, to set the output current range, the DS4432 pro-
_______________________________________________________________________________________
FS
FS
voltage (see the DC Electrical Characteristics
is the desired full-scale current value, V
FS
I
OUT
2
is the external resistor value.
C interface for control. The adjustable
R
=
FS
D
Detailed Description
=
AC Value dec
16 I
V
RFS
×
1
2
C adjustable current DACs
27
FS
FS
(
(connected to the FSx
× 127
)
2
OUT
×
C, 7-Bit Sink/Source
I
FS
) based on the
2
C inter-
RFS
is
To control the DS4432’s current sources, write to the
memory addresses listed in Table 1.
Table 1. Memory Addresses
The format of each output control register is:
where:
Example: R
a value of 0xAAh. Calculate the output current.
The MSB of the output register is 1, so the output is sourc-
ing the value corresponding to position 2Ah (42 decimal).
The magnitude of the output current is equal to:
The DS4432’s slave address is 90h.
The following terminology is commonly used to describe
I
2
BIT
D
MSB
C data transfers:
S
X
S
Master Device: The master device controls the slave
devices on the bus. The master device generates
SCL clock pulses and START and STOP conditions.
MEMORY ADDRESS
I
2
I
NAME
FS
Data
Sign
C Serial Interface Description
Bit
D
= (0.997V/80kΩ) x (127/16) = 98.921µA
6
(HEX)
FS0
98.921µA x (42/127) = 32.714µA
F8h
F9h
Determines if DAC sources or
sinks current. For sink
S = 0; for source S = 1.
7-Bit Data Controlling DAC
Output. Setting 0000000b
outputs zero current regardless
of the state of the sign bit.
= 80kΩ and register 0xF8h is written to
D
5
FUNCTION
D
4
Memory Organization
D
3
I
CURRENT SOURCE
2
C Slave Address
I
D
2
2
C Definitions
OUT0
OUT1
POWER-ON
D
DEFAULT
0000000b
1
0b
LSB
D
0