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AN-1289
APPLICATION NOTE
One Technology Way • P. O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Te l: 781.329.4700 • Fax: 781.461.3113 • www.analog.com
Using the AD5755 and Similar Dynamic Power Control DACs
in Applications Without Dynamic Power Control
by David Rice
Rev. 0 | Page 1 of 8
INTRODUCTION
This application note describes using the AD5755 and other
similar industrial DACs in applications that do not require the
dynamic power control (DPC) feature.
This group of products consists of five industrial DACs, which
have multiple options to suit various applications. Table 1 lists
and highlights the features of each DAC.
DPC operates by sensing the load on the current output pin and
supplying only the power that is required. To achieve this, the
AD5755, for example, controls a dc-to-dc converter to step up a
5 V supply to between 7.4 V and 29.5 V.
DPC is particularly useful in systems with wide load ranges
including a short-circuit condition (0 Ω load to ground) where
all power generated by the supply is dissipated on chip. In non-
DPC systems, this results in higher IC temperatures that
increase overall system temperatures.
DC-TO-DC
CONVERTER
POWER
CONTROL
7.4V TO 29.5V
REG
V
SEN1
V
SEN2
SW
V
BOOST
DAC
R1
R2
R3
A
V
CC
5.0V
I
OUT
12049-001
Figure 1. AD5755 with Dynamic Power Control
There are low power applications that may not require dynamic
power control. In these cases, the dc-to-dc converter can be
excluded from the design. This reduces the number of external
components and is useful for applications with space-
constraints that require the AD5755 quad-channel feature.
This application note describes two alternatives to using the dc-
to-dc converter. The first method uses an external PMOS to
limit on-chip power dissipation. The second method involves
powering the DAC directly with all power dissipated directly
on chip. Each method describes the setup and calculates total
power dissipation both on and off chip.
Table 1. AD5755 and Similar Dynamic Power Control DACs
ADC Features
AD5755
16-Bit, Quad Channel, Current and Voltage Output
DAC
AD5755-1
16-Bit, Quad Channel, Current and Voltage Output
DAC with HART Connectivity
AD5735
12-Bit, Quad Channel, Current and Voltage Output
DAC
AD5757
16-Bit, Quad Channel, Current Output DAC with
HART Connectivity
AD5737
12-Bit, Quad Channel, Current Output DAC with
HART Connectivity
