DDX-2100
DDX-2100 POWER DEVICE
The DDX-2100 Power Device is a dual channel
H-Bridge that can deliver over 50 watts per
channel of audio output power at very high
efficiency. It converts DDX controlled PWM
signals to power at the load. The DDX-2100
includes a logic interface, integrated bridge
drivers, high efficiency MOSFET outputs, thermal
and short circuit protection circuitry. Two logic
level signals per channel are used to control high-
speed MOSFET switches to connect the speaker
load to the input supply or to ground in a bridge
configuration, according to Apogee's patented
damped ternary PWM. The DDX-2100 includes
over-current, thermal and under-voltage lockout
with automatic recovery. A thermal warning
status is also provided.
Figure 4. DDX-2100 Block Diagram
Logic Interface and Decode
The DDX-2100 power outputs are controlled using
two logic level timing signals. In order to provide
a proper logic interface, the VL input must operate
at the same voltage as the DDX controller logic
supply.
Protection Circuitry
The DDX-2100 includes protection circuitry for
over-current and thermal overload conditions. A
thermal warning pin TWARN is activated low
(open-drain MOSFET) when the IC temperature
exceeds 130°C, in advance of the thermal
shutdown protection. When a fault condition is
detected (logical OR of over-current and thermal),
an internal fault signal acts to immediately disable
the output power MOSFETs, placing both H-
bridges in a high impedance state. At the same
time an open-drain MOSFET connected to the
FAULT pin is switched on. There are two possible
modes subsequent to activating a fault. The first
is a SHUTDOWN mode. With FAULT (pull-up
resistor) and TRI-STATE pins independent, an
activated fault will disable the device, signaling
low at the FAULT output. The device may
subsequently be reset to normal operation by
toggling the TRI-STATE pin from High to Low to
High using an external logic signal. The second is
an AUTOMATIC recovery mode. This is depicted
in the application circuit, Figure 2. The FAULT
and TRI-STATE pins are shorted together and
connected to a time constant circuit comprising
RT and CT. An activated FAULT will force a reset
on the TRI-STATE pin causing normal operation
to resume following a delay determined by the
time constant of the circuit. If the fault condition is
still presented, the circuit operation will continue
repeating until such time as the fault condition is
removed. An increase in the time constant of the
circuit will produce a longer recovery interval.
Care must be taken in the overall system design
so as not to exceed the protection thresholds
under normal operation.
Logic I/F
and Decode
Left
H-Bridge
Protection
Circuitry
INL[1:2]
INR[1:2]
VL
PWRDN
TRI-STATE
OUTPL
FAULT
TWARN
OUTNL
OUTPR
OUTNR
Regulators
Right
H-Bridge
Power Outputs
The DDX-2100 power and output pins are
duplicated to provide a low impedance path for
the devices bridged outputs. All duplicate power,
ground and output pins must be connected for
proper operation. The PWRDN or TRI-STATE
pins should be used to set all MOSFETS to the
Hi-Z state during power-up until the logic power
supply, VL, is settled.
Parallel Output/High Current Operation
The DDX-2100 outputs can be connected in
parallel to increase the output current to a load. In
this configuration the device can provide over
100W into 4
(see Figure 3)
.
This mode is
enabled with the CONFIG pin connected to
VREG1 and the inputs combined INLA = INLB,
INRA = INRB and outputs combined OUTLA =
OUTLB, OUTRA = OUTRB.
ADDITIONAL INFORMATION
Output Filter
A passive two-pole low pass filter is used on the
DDX-2100 power outputs to reconstruct an analog
signal. System performance can be significantly
affected by the output filter design and choice of
components. A filter design for 8
loads is shown
in Figure 2, and for 4
loads in Figure 3.
6
Document #11010001-01
November 2001
PRELIMINARY – subject to change without notice