Diodes PAM8610 - Manual (Page 12)

PAM8610
Document number: DSxxxxx Rev. 1 - 2
12 of 15
www.diodes.com
June 2013
© Diodes Incorporated
PAM8610
A Product Line of
Diodes Incorporated
Application Information
(cont.)
Selection of COSC and ROSC
The switching frequency is determined by the values of components connected to R
OSC
(pin 23) and C
OSC
(pin 22) and calculated as follows:
f
OSC
= 2 π/ (R
OSC
* C
OSC
)
The frequency may varies from 225kHz to 275kHz by adjusting the values of R
OSC
and C
OSC
. The recommended values are C
OSC
= 220pF,
R
OSC
= 120k Ω 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. 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 1µF BST capacitor to replace 220nF (pin15, pin 16, pin 35 and pin 36) for lower than 100Hz applications.
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 1 μF 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 V
CC
and may not be used to power any other circuitry.
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 0.1 μF 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.
Differential Input
The differential input stage of the amplifier eliminates noises that appear on the two input lines of the channel. To use the PAM8610 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 PAM8610 with a single-ended source, acground 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 acgrounded at the audio source other than
at the device input for best noise performance.
Using Low-ESR Capacitors
Low- ESR capacitors are recommended 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.
Short-Circuit Protection
The PAM8610 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-V
CC
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 SD the 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.
Thermal Protection
Thermal protection on the PAM8610 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.