PAM8606
6W Stereo Class-D Audio Power Amplifier with DC Volume Control
-resistance (ESR) ceramic capacitor, typically
Differential Input
1μF, is recommended, placing as close as
possible to the device’s VCC lead. To filter lower-
frequency noises, a large aluminum electrolytic
capacitor of 10μF or greater is recommended,
placing near the audio power amplifier. The 10μF
capacitor also serves as a local storage capacitor
for supplying current during large signal
transients on the amplifier outputs.
The differential input stage of the amplifier
eliminates noises that appear on the two input
lines of the channel. To use the PAM8606 with a
differential source, connect the positive lead of
the audio source to the INP input and the negative
lead from the audio source to the INN input. To
use the PAM8606 with a single-ended source, ac-
ground the INP input through a capacitor equal in
value to the input capacitor on INN and apply the
audio source to the INN input. In a single-ended
input application, the INP input should be ac-
grounded at the audio source other than at the
device input for best noise performance.
Selection of COSC and ROSC
The switching frequency is determined by the
values of components connected to ROSC (pin
23) and COSC (pin 22) and calculated as follows:
Using low-ESR Capacitors
fOSC = 2π / (ROSC * COSC
)
L o w - E S R c a p a c i t o r s a r e r e c o m m e n d e d
throughout this application section. A real (with
respect to ideal) capacitor can be modeled simply
as a resistor in series with an ideal capacitor. The
voltage drop across this resistor minimizes the
beneficial effects of the capacitor in the circuit.
The lower the equivalent value of this resistance
the more the real capacitor behaves as an ideal
capacitor.
The frequency may varies from 225kHz to 275kHz
by adjusting the values of ROSC and COSC. The
recommended values are CO S C = 220pF,
ROSC=120kΩ for a switching frequency of 250kHz.
BSN and BSP Capacitors
The full H-bridge output stages use NMOS
transistors only. They therefore require bootstrap
capacitors for the high side of each output to turn
on correctly. A at least 220nF ceramic capacitor,
rated for at least 25V, must be connected from
each output to its corresponding bootstrap input.
Specifically, one 220nF capacitor must be
connected from xOUTP to xBSP, and another
220nF capacitor from xOUTN to xBSN. It is
recommended to use 1ꢀF BST capacitor to
replace 220nF (pin18, pin19, pin42 and pin43)
for lower than 100Hz applications.
Short-circuit Protection
The PAM8606 has short circuit protection circuitry
on the outputs to prevent damage to the device
when output-to-output shorts, output-to-GND
shorts, or output-to-VCC shorts occur. Once a
short-circuit is detected on the outputs, the output
drive is immediately disabled. This is a latched
fault and must be reset by cycling the voltage on
the SD pin to a logic low and back to the logic high
state for normal operation. This will clear the
short-circuit flag and allow for normal operation if
the short was removed. If the short was not
removed, the protection circuitry will again
activate.
VCLAMP Capacitors
To ensure that the maximum gate-to-source
voltage for the NMOS output transistors not
exceeded, two internal regulators are used to
clamp the gate voltage. Two 1μF capacitors must
be connected from VCLAMPL and VCLAMPR to
ground and must be rated for at least 25V. The
voltages at the VCLAMP terminals vary with VCC
and may not be used to power any other circuitry.
Thermal Protection
Thermal protection on the PAM8606 prevents
damage to the device when the internal die
temperature exceeds 150°C. There is a 15
degree tolerance on this trip point from device to
device. Once the die temperature exceeds the set
thermal point, the device enters into the shutdown
state and the outputs are disabled. This is not a
latched fault. The thermal fault is cleared once the
temperature of the die is reduced by 40°C. The
device begins normal operation at this point
without external system intervention.
Internal Regulated 5-V Supply (AVDD)
The AVDD terminal is the output of an internally-
generated 5V supply, used for the oscillator,
preamplifier, and volume control circuitry. It
requires a 0.1μF to 1μF capacitor, placed very
close to the pin to Ground to keep the regulator
stable. The regulator may not be used to power
any external circuitry.
Power Analog Microelectronics,Inc
www.poweranalog.com
08/2008 Rev 1.1
14
PAM [ POWER ANALOG MICOELECTRONICS ]
