Infinity DPA 275 Programming manual

Winfini
CAR AUDIO
DPA
275/250
Digital
&
Power
Amplifier
Owner’s Manual
Installation Guide

Owner’s Manual and Installation Guide
FEATURES...
HPDA CONVERTERS
HiGH EFFICIENCY
Introduction a
se al a a ar rm S gS A NT
INTRODUCTION
The Infinity DPA 275/250 Digital Power Amplifier
is a breakthrough innovation for the mobile audio
after-market. You now own a digital amplifier that
car audio enthusiasts everywhere have only
dreamed of — until now! The DPA 275/250 is the next
generation of amplification, and it makes all other
mobile amplifier technologies obsolete.
The DPA 275 offers stereo, bridged-mono, or tri-
mode operation, and delivers 75 watts (rms) per
channel into a 4-ohm load. The DPA 250 produces
50 watts (rms) per channel operating in stereo.
Otherwise, both models come with these features:
¢ Our innovative Differential Amplification Output
Switching is the design essence of this product
HPDA (High Power Digital-to-Analog) Converter
on each channel to directly convert digital signals
into amplified analog audio waveforms
* Custom-Designed High-Speed MOSFET
Switching Power Supply to supply voltages for
internal circuits
Five protection levels guard against Over-Voltage,
Under-Voltage, Over-Power, Over-Temperature,
and Over-Current situations
¢ High efficiency ~ requires far less electrical power
and generates a smaller amount of heat
*
Small footprint ~ when compared to conventional
Class AB amplifiers with equivalent power ratings
¢ Amplifier input sensitivity control — to match a
wide range of input signal levels
The DPA 275 has a bass equalization control to
provide up to 11 dB of bass boost at 40 Hz
Color-keyed, industrial-grade, gold-plated
connections — easy-to-install high-quality interface
e
Connection cover ~ defeats tampering with
installation wiring
Rugged, sleek-looking case — built for the road,
yet is still a showpiece

SOlnfinity
Asout THIS
MANUAL...
PPA: 207 20:0
This Infinity product is made with our ongoing
dedication to create the best consumer audio
products possible. As a result, you can expect your
DPA 275/250 Digital Power Amplifier to provide you
with many years of listening enjoyment.
Save these instructions for future reference. All
Infinity Automotive Products carry a limited one-
year parts and labor warranty, so retain the bill of
sale to protect your purchase in the unlikely event
of failure during the warranty period.
To attain maximum amplifier performance, we
encourage you to read the remaining pages before
installing and operating the Infinity DPA 275/250
Digital Power Amplifier. Since this product is such
a radical departure from any other amplifier
available today, we’ve devoted the next section to a
Technical Overview, so you can understand what's
going on inside the chassis.
TABLE OF CONTENTS
TECHNICAL OVERVIEW....cccccoceccccccccssccseessened
DESIGNING IT WASNT EASY....cccccccccvevcccscscend
HiGH-SPEED MOSFET POWER SUPPLY....ccscsees
NEW DIGITAL TECHNOLOGY ..cccccscccccscsccsscceses@
[APPLICATIONS cccccsssscessesesececcscccseseessereersase®
STEREO: SYSTEM cecssaccscecccdsustcienncasvassestessonsc®
BRIDGED-MONO (DPA 275 ONLY) .cccccsssseseee
TRI-MODE (DPA 275 ONLY)....cccsscccorsvesenes IO
PRECAUTIONS AND NOTES.......cccscccsssccssveel |
INSTALLATION .....ccssccccccssscccccscccccessscsscccssest
PARTS: EIST ccccvscscssccsdcnccsexsaateacastdeasscescccielo
MOUNTING cocseciscccictsccescescccteecetaccieusaesissclo
WIRING sessccccaseicsccacévaveuescudanscacensncsccucese 4
SETTING INPUT SENsiTIviTY AND BAss EQ......15
INSTALLING THE COVER....cccscccscssnescreccsenscceel@
IN CASE OF TROUBLE. ..cosccovscccvccescccssessoeseselO
SPECIFICATIONS eas eb bdeuadceuwaseeaeseneseccaseackeonslh
2 Table Of Contents

Owner’s Manual and Installation Guide
TECHNICAL OVERVIEW
DESIGNING IT Creating a digital car amplifier is no small feat. In
fact, we've devoted the equivalent of over 5000 man-
WASN’T EASY... hours to developing and testing prototypes to come
| up with the unique design used in the Infinity DPA
Digital Power Amplifier. Along every step of the way,
we gained insight about how to solve major design
obstacles — like temperature and humidity extremes,
widely-varying electrical system voltages, complex
load impedances, RFI (radio frequency interference)
concerns, and a multitude of interface options.
As a result, we had to develop several unique circuit
topologies for the Infinity DPA series amplifier, as
shown in Figure 1.
rr i
FET Switch
35 Vde
Rectifiers and -15 Vde
Filters to Convert
125 kHz fo
Fnergy Storage
Capacitors and
RF| Filters
Ground
+10 tat. 5 Vde
(from battery)
Common
filtered 415 Vde
DC valtages
+ 35 Vdc
FET Switch
ee
an Controland |--------+-----'
Remote Turr-On 195 Khz Clock
Over Voltage Sensor
ea Voltage Sensor DPA HIGH-SPEED
ver Power Sensor
Over Temperature Sensor MOSFET SWITCHING
Over Current Sensors POWER SUPPLY
+35 Vde (from
Rower Supply] High Power
FET sui | Digital-to-Analog [HPDA]
> Converter Changes PWM Pulses
Modulator Converts to Analog Audio
Audio Input Analog Audio Voltage to Audio Output
Pulse-Width-Modulated
Digital Signo!
fone channel)
aC
[one channel)
Tg. = NN,
- 35 Vde {from
Power Supply]
Feedback
DPA DIGITAL SWITCHING
AMPLIFICATION
Figure 1. A DPA series amplifier contains a High-Speed MOSFET Sunutching
Power Supply and Digital Output Switching Amplification technology.
Technical Overview EJ

SOInfinity DPA 2757250
HIGH-SPEED To create the de voltages required by the
DPA 275/250’s internal circuits, we designed a new
MOSFET Power high-speed MOSFET Switching Power Supply.
Rather than use off-the-shelf [Cs Gintegrated
SUPPLY... circuits), we developed a unique voltage doubler
circuit that has a constant frequency and duty cycle,
with a short signal path.
This technique produces a power supply with a high
90 percent efficiency rating, regardless of normal
battery voltage. When combined with the other
circuits, an overall amplifier efficiency of 80 percent
is attained, measured as the ratio of power out to
the speakers versus power from the battery.
Why Is HiGH Before we go on, here’s why you should be concerned
about a high efficiency rating. Literally, it means a
ErriciENCY SO DPA 275/250 amplifier will convert more of your
vehicle’s valuable electrical power into useful audio
IMPORTANT? power, than a Class AB analog amplifier with the
same power rating. The electrical system won't be
strained, and much less energy will be turned into
wasted heat.
Efficiency
100%
90%
DPA 275
8 0% a : | Se oan ee
) es
~
70%
Operating
Ronge
For
Music
:
See,
one Reproduction — we ee
50% i Me ,
: conventional
ie amplifier
40% al
30%
20% | )
20 40 60 80 100 120 140 160
Figure 2. Efficiency versus power output for a DPA 275 and a conventional
analog car amplifier driven by a dc-to-de converter.
4 | Technical Overview

cA
EFFICIENCY AND
Music REPRODUCTION
ADVANTAGES OF A
HIGHER Crock RATE
wner’s Manual and |
tm a
sha lavion Gauide
——_—__=.
Efficiencies are typically measured at the
amplifier’s full power rating. However, a close look
at a power output versus efficiency curve shows that
efficiency varies directly as a function of the power
output level. This is more apparent when music is
the source, as opposed to a sine wave test.
Figure 2 (on the opposite page) shows measured
efficiencies versus power output levels for a DPA 275
and a conventional analog amplifier driven by a de-
to-de converter. |
Notice that the DPA 275 operated at over 80 percent
efficiency over a range of 40 to 80 watts, resulting in
very little wasted energy. In other words, for every
100 watts of battery power in, the DPA 275 delivered
80 watts of music power to the loudspeaker!
Moreover, when music is the source, an amplifier will
operate at approximately one-third of its rated output
(in this case 40 to 80 watts). This is exactly where the
DPA 275 (or DPA 250) is most efficient during the
most-used area of operation — music reproduction.
In the digital world, a clock is a circuit which serves
as a single source of pulses for use by other circuits,
and clock rate is the number of pulses that occur per
unit of time, measured in Hertz. The DPA 275/250
power supply uses a higher clock rate (125 kHz,
versus 30 kHz in typical designs), which presents
several advantages. First, the size of components
and the accompanying package is smaller. This
insures that generated RFI is not audible and will
not interfere with the amplifier’s switching
frequencies. In addition, a pair of asynchronous
clocks, controlling the switching circuits of the
power amplifiers, operate at different frequencies on
the left and right channels to eliminate the
possibility of any heterodyne (1.e., radio beat) effect.
In addition, the pe board’s ground plane is coupled
electrostatically to the chassis, to control virtually all
RFI generated by the 500 kHz carrier (see page 6).
Five protection sensors monitor over-voltage, under-
voltage, over-power conditions, over-temperature
limits, and over-current use. This unparalleled
protection scheme allows the DPA 275/250 to operate
continually over a range of battery voltages from
10 to 15.5 V de at all temperature extremes.
Technical Overview

Q9INfiniky
New DIGITAL
TECHNOLOGY...
INCORPORATES
HPDA Converters
DPA. 2757750
To amplify audio, we developed a new technology
called Differential Amplification Output Switching.
As shown in Figure 1 (on page 3), it consists of a
proprietary 500 kHz pulse-width modulation circuit,
to sample and convert incoming analog audio to
digital “1-bit” pulses (which is the equivalent of an
11-times oversampling rate in digital audio terms).
The high modulation frequency insures precision
sampling that is free of audible RFI artifacts, and
also allows us to use passive, gentle-slope filtering —
for minimum phase shift when the analog waveform
is reconstructed at the output. In essence, we have
incorporated a High Power D-to-A (HPDA)
converter within the design. The digital pulses
control a complementary pair of fast, high-current
MOSFET switches that create amplified 70 V de
pulses across the voltage rails. Two-stage RFI
filtering removes the 500 kHz carrier frequency, and
the result is a pure amplified analog signal that is
transparent and adds no sound of its own! To better
understand how an analog signal is extracted from
a digital pulse-width waveform, refer to Figure 3
during the following discussion.
50 % duty analog PYM
duty cycle audio / se
7 ae. signal / son
: i il I.
Figure 3. Duty cycle ts a measurement of the time a digital signal is on versus
the time it is off over one cycle of the waveform. It is expressed as a percentage
(e.g., a 50 % duty cycle means the signal is on half of the time). A positive voltage
increase in the analog audio signal translates to an increased duty cycle in the
pulse-width modulated (PWM) digital signal.
RB echnical Overview
——— ee... + re

Owner’s
Manual
and
Installation
Guide
pay
HPDA CONVERTERS
AmpPLIFY AND
RECONSTRUCT THE
ANALOG SIGNAL
A Worp Asout
LOAD IMPEDANCES
Figure 4, Frequency
response for a DPA 275
with both channels
driving loads of 2, 4, and
8 ohms. Note the
differences in the high
frequencies when
compared to the
optimum 4-ohm. response.
When there is no incoming audio signal, the
modulator circuit creates a pulse-width waveform
having a 50 % duty cycle. This means the waveform —
spends half of its time at +35 V de and the other half
of its time at -35 V dc. When you sum (i.e., average)
the areas under each positive and negative
excursion (in the way our HPDA does), you get a net
result of zero — or no voltage output. Let’s assume
an instantaneous positive voltage is now present at
the analog input, and the modulator shifts the duty
cycle of the pulse-width waveform, so more time is
spent at +35 V de than at the -35 V dc rail. When
these areas are averaged, a positive value at the
output is the net result. Repeating this process
creates a continuous amplified analog waveform
from the stream of 500 kHz samples.
For optimum performance, the DPA 275/250 should
only drive a 4-ohm load. As in crossover filter design,
there is a direct result of having to specify a load
impedance in order to build the output filters used in
the HPDA converter. We choose 4 ohms as the best
compromise between the most common values of
8 and 2 ohms. Other loads can be used, but they will
change filter characteristics and affect the
amplifier’s frequency response, as shown in Figure 4.
With an 8-ohm load, the DPA 275/250 response rises
in the high frequencies to produce a brighter sound.
Conversely, with a 2-ohm load, the high frequency
response rolls off faster for a duller sound. In
addition, protection circuits will activate sooner to
safeguard the amplifier.
Level {dB}
Frequency (Hz)
Technical Overview 7

ROinfinity DPA 275/250
APPLICATIONS
For your convenience, we've included several
application diagrams to help you plan your own
installation. Figures 5 through 7 show how to
configure the DPA 275 for stereo, bridged-mono, or
tri-mode operation. For the DPA 250, only Figure 5
will apply.
Figure 5. Wiring
diagrams for stereo
operation of DPA 275
and DPA 250 amplifiers.
When hooked-up as
shown, amplifier
outputs are in phase.
DPA 275
Amplifier
Stereo Mode
L speaker R speaker
DPA 250
Amplifier
Stereo Mode
L speaker R speaker
a oo ae
8 Applications

Owner's Manual and Installation Guide
me ne
Figure 6. Wiring
diagram for operating
the DPA 275 amplifier
in a bridged-mono
configuration. In this
mode, only the right
channel’s RCA input | DPA 2 /9
jack is active. i Am ol itier
Mono Mode
subwoofer
- Applications aA