APA2605 Datasheet, PDF (18/30 Pages) Anpec Electronics Coropration – 2.8W Stereo Class-D Audio Power Amplifier

APA2605
Function Description (Cont.)
Table 1: AGC Setting Threshold v.s Output Power
AGC Function
Output Power
VDD~0.45VDD
0.45VDD~0.27VDD
0.27VDD~GND
(AGC Floating)
Disable AGC Function
P_O
=
8x0.95

1
2
VDD − V_AGC ²

RL
(Max Output Power 4Ω) Po=2.513W
(Max Output Power 8Ω) Po=1.26W
Shutdown Operation
In order to reduce power consumption while not in use,
the APA2605 contains a shutdown function to externally
turn off the amplifier bias circuitry. This shutdown feature
turns the amplifier off when logic low is placed on the SD
pin for APA2605. The trigger point between a logic high
and logic low level is typically 0.65V. It is the best to switch
between ground and the supply voltage V to provide
DD
maximum device performance. By switching the SD pin
to a low level, the amplifier enters a low-consumption-
current state, I_DD for APA2605 is in shutdown mode. On
normal operating, APA2605’s SD pin should pull to a high
level to keep the IC out of the shutdown mode. The SD pin
should be tied to a definite voltage to avoid unwanted
state changes.
Over-Current Protection
The APA2605 monitors the output current, and when the
current exceeds the current-limit threshold, the APA2605
turn-off the output stage to prevent the output device from
damages in over-current or short-circuit condition. The IC
will turn-on the output buffer after 1ms, but if the over-
current or short-circuits condition is still remain, it enters
the Over-Current protection again. The situation will cir-
culate until the over-current or short-circuits has be
removed.
Thermal Protection
The over-temperature circuit limits the junction tempera-
ture of the APA2605. When the junction temperature ex-
ceeds T =+150^oC, a thermal sensor turns off the output
J
buffer, allowing the devices to cool. The thermal sensor
allows the amplifier to start-up after the junction tempera-
ture going down to about 125^oC. The thermal protection
is designed with a 25^oC hysteresis to lower the average
T during continuous thermal overload conditions, in-
J
creasing lifetime of the IC.
Copyright © ANPEC Electronics Corp.
18
Rev. A.7 - Mar., 2013
www.anpec.com.tw