LM4840LQ National Semiconductor, LM4840LQ Datasheet - Page 14

• Manufacturer Part Number: LM4840LQ
• Description: Stereo 2W Audio Power Amplifiers with Digital Volume Control and Input Mux
• Manufacturer: National Semiconductor

www.national.com
Application Information
Table 1: Logic Level Truth Table
*Beepdetect signal overrides any mute. For example, if amp is muted and bpdetect is HIGH, then amp is no longer muted.
**Dual mode: When HP jack is inserted, load A (speaker corresponding to outputs A- and A+) is physically disconnected. Load
B remains connected; however, amp B+ is off and differentially there is no voltage across it. If a beep is detected (i.e. beepdetect
= HIGH), then summed signal (audio + beep signals) is heard in the headphones and on speaker B.
*Next four conditions, beep is detected; beep signal added to audio signal and bypasses volume control (unity)
*Next eight conditions turns off all amps
SD
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
L
DETECT
BEEP
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
L
MUTE
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
L
SENSE
HP
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
L
(Continued)
BTL SPK
BTL SPK
BTL SPK
BTL SPK
BTL SPK
BTL SPK
BTL SPK
BTLSPK
MODE
HP
HP
HP
HP
HP
HP
HP
HP
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
14
ON
ON
ON
ON
ON
ON
ON
ON
R-
ON (buffer)
ON (buffer)
ON (buffer)
ON (buffer)
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
ON
ON
ON
R+
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
ON
ON
ON
ON
ON
ON
ON
L-
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
ON
ON
ON
ON
ON
L+
*Amps are muted
*Amps are muted
*Dual Mode
*Dual Mode