ft2925
2x6W Class-G Stereo Audio Power Amplifier
with Automatic Level Control & Battery Tracking AGC
FEATURES
GENERAL DESCRIPTION
Wide range of supply voltages from 3V to 5.5V
The ft2925 is a highly efficient 2x6W Class-G stereo
audio power amplifier with automatic level control (ALC)
and battery tracking AGC. It integrates dual filterless
Class-D audio amplifiers with a multi-level Class-G
synchronous boost regulator and operates with a range
of supply voltages from 3V to 5.5V. When operating
with a 3.6V supply voltage, the ft2925 can deliver an
output power of 6W per channel with 10% THD+N, or
an ALC output power of 4.5W per channel with 0.3%
THD+N, into a pair of 4Ω speakers.
Dual filterless Class-D audio amplifiers integrated
with a multi-level Class-G boost regulator
Automatic level control to eliminate output clipping
Battery tracking AGC to prevent battery collapse
Soft drive mode for EMI reduction
Maximum output power (Non-ALC Mode)
(VBAT=3.6V, ALC=High, THD+N=10%)
6.0W/Ch (4Ω Load)
3.5W/Ch (8Ω Load)
ALC output power (ALC Mode)
In ft2925, the power supply rails of the audio amplifiers’
output stages are internally boosted and regulated by a
synchronous PWM switching regulator with two
integrated power switches. The boost regulator
employs current-mode PWM control with proprietary
multi-level Class-G operation to regulate the boosted
output voltage dynamically in response to the voltage
level of the audio outputs.
(VBAT=3.6V, ALC=Low, THD+N=0.3%)
4.5W/Ch (4Ω Load)
2.6W/Ch (8Ω Load)
Wide ALC dynamic range: 12dB
Maximum voltage gain: 30dB
High efficiency: 78%
(VBAT=3.6V, 4Ω Load, Po=2W/Ch, both channels driven)
Volume fade-in and fade-out
The ft2925 features ALC function to constantly monitor
and safeguard the audio outputs against the boosted
supply voltages, preventing output clipping distortion,
excessive power dissipation, and speaker over-load.
Once an over-level condition is detected in either
channel, the ALC lowers the voltage gain of both audio
amplifiers together to limit the peak audio outputs.
Under-voltage lockout protection
Auto-recovering over-current & short-circuit
protection
Thermal over-load protection
Available in TSSOP-28L package
APPLICATIONS
In conjunction with ALC, as the battery supply voltage
drops below a prescribed value, the battery tracking
AGC lowers the voltage gain of both audio amplifiers to
limit the peak audio outputs, preventing the collapse of
battery voltage.
Blue Tooth Speakers
Portable Audio Decks
Consumer Audio Electronics
APPLICATION CIRCUIT
VDD
CVBAT
1uF
RS1 10Ω
1
28
VBAT
INNL
INPL
AGND
Cin 0.22uF
Cin 0.22uF
15K
15K
Rin
Rin
2
3
27
26
25
24
23
22
21
20
19
18
17
16
15
Rin 15K
Rin 15K
INNL
INPL
INNR
INPR
INNR
INPR
Cin
0.22uF
Cin
0.22uF
4
PGND
VOPL
VONL
PVDDL
AVDD
BVDD
NC
PGND
VOPR
VONR
PVDDR
PVSNS
PVOUT
PVOUT
PGNDB
PGNDB
LX
LSL
SPEAKER
PVDD
LSR
5
6
SPEAKER
PVDD
7
CPVDDL
1uF
8
CPVDDR
1uF
CAVDD
1uF CBVDD
0.1uF
9
RS2 10Ω
10
11
12
13
14
CPVOUT
220uF
CPVOUT
0.1uF
+
VKNEE
ALC
SDRIVE
EN
EN
LX
ft2925
VDD
L
3.3uH
D1 SS34
CS
22uF
CS
0.1uF
CPVOUT
22uF
Figure 1: Typical Application Circuit Diagram of ft2925
DEC, 2017
www.fangtek.com.cn
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