DS4404 Maxim Integrated Products, Inc., DS4404 Datasheet - Page 8

• Manufacturer Part Number: DS4404
• Description: Two/four-channel, I2c Adjustable Current Dac
• Manufacturer: Maxim Integrated Products, Inc.

Using the typical circuit, assuming a typical output volt-
age of 2.0V, a feedback voltage of 0.8V, R1 = 500Ω,
and R2 = 333Ω, to adjust or margin the supply 20%
requires a full-scale current equal to [(0.2 x 2.0V) /
500Ω = 800µA]. Using Equation 1, R
ed [R
rent DAC in this configuration allows the output voltage
to be stepped linearly from 1.6V to 2.4V using 63 set-
tings. This corresponds to a resolution of 12.7mV/step.
The feedback voltage for adjustable power supplies
must be between 0.5V and V
DS4404 to properly sink/source currents for adjusting
the voltage.
In addition to defining the I
DS4404 address select inputs have an alternate function.
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2006 Maxim Integrated Products
Two/Four-Channel, I
Figure 4. I
TRANSISTOR COUNT: 10,992
Pages changed at Rev1: 1, 4
TYPICAL I
START
A)
B)
EXAMPLE I
SINGLE BYTE WRITE
-WRITE RESISTOR
SINGLE BYTE READ
-READ RESISTOR F8h
F9h TO 00h
FS
MSB
2
a7
C WRITE TRANSACTION
= (V
2
2
is a registered trademark of Dallas Semiconductor Corporation.
C TRANSACTIONS (WHEN A0 AND A1 ARE N.C.)
C Communication Examples
a6
REF
Power-Supply Feedback Voltage
for an Adjustable Power Supply
a5
ADDRESS*
/ 800µA) x (31 / 4) = 11.9kΩ]. The cur-
I
Application Information
SLAVE
2
START
START
a4
C Reset on Address Change
a3
1 0 1 0 0 0 0 0
1 0 1 0 0 0 0 0
a2
2
A0h
A0h
C slave address, the DS4402/
Example Calculations
Chip Information
Revision History
a1
CC
READ/
WRITE
R/W
LSB
- 0.5V for the DS4402/
SLAVE
SLAVE
ACK
ACK
SLAVE
FS
ACK
1 1 1 1 1 0 0 1
1 1 1 1 1 0 0 0
can be calculat-
MSB
F9h
F8h
b7
b6
REGISTER/MEMORY ADDRESS
2
SLAVE
SLAVE
*THE SLAVE ADDRESS IS DETERMINED BY ADDRESS PINS A0 AND A1 (SEE TABLE 1).
b5
ACK
ACK
C Adjustable Current DAC
b4
0 0 0 0 0 0 0 0
REPEATED
START
b3
b2
Changing the address select inputs resets the I
face. This function aborts the current transaction and puts
the SDA driver into a high-impedance state. This hard-
ware reset function should never be required because it
is achievable through software, but it does provide an
alternative way of resetting the I
To achieve the best results when using the DS4402/
DS4404, decouple the power supply with a 0.01µF or
0.1µF capacitor. Use a high-quality ceramic surface-
mount capacitor if possible. Surface-mount compo-
nents minimize lead inductance, which improves
performance, and ceramic capacitors tend to have
adequate high-frequency response for decoupling
applications.
Care should be taken to ensure that traces underneath
the DS4402/DS4404 do not short with the exposed pad.
The exposed pad should be connected to the signal
ground, or can be left floating.
For the latest package outline information, go to
www.maxim-ic.com/DallasPackInfo.
1 0 1 0 0 0 0 1
is a registered trademark of Maxim Integrated Products, Inc.
b1
SLAVE
ACK
A1h
LSB
b0
STOP
SLAVE
ACK
SLAVE
ACK
MSB
b7
b6
DATA
Package Information
b5
b4
Layout Considerations
DATA
MASTER
NACK
b3
2
C interface, if needed.
b2
STOP
V
b1
CC
LSB
b0
Decoupling
SLAVE
ACK
2
C inter-
STOP