下载
SN74LVC1G3157 and SN74LVC2G53 SPDT Analog Switches
Overview of SPDT Analog Switches
Texas Instruments (TI) broadens its
signal switch portfolio with the
SN74LVC1G3157 and SN74LVC2G53
devices. The main difference between
these devices is both channels on the
LVC2G53 can be placed into high imped-
ance providing further flexibility. These
2:1 Multiplexer/Demultiplexer Analog
Switches are better known as Single-
Pole/Double-Throw (SPDT) switches in
the analog realm. Designed for 1.65-V to
5.5-V V
CC
operation, these devices can
handle both analog and digital signals and
permit signals with amplitudes of up to
V
CC
(peak) to be transmitted in either
direction without clipping. Applications
include analog signal routing, signal
R ELIABLE. LOGIC. INNOVATION.
TM
gating, chopping and digital signal
multiplexing/demultiplexing.
The devices are available in industry
standard 6-pin [SC-70 (DCK) and SOT-23
(DBV)] and 8-pin (SSOP, VSSOP and
NanoStar™) packages, making them
extremely well suited for space-
constrained, portable applications
such as PDAs, cell phones and other
handheld products.
LVC1G3157
Control Input On Channel
S
LB1
HB2
LVC2G53
Control Input On
INH A Channel
LL Y1
LH Y2
HX None
In this Smart PDA application the voice and music
differential audio signals can be routed using the LVC1G3157
and LVC2G53 analog switches. When either voice or data is
selected, the analog signal is transmitted to both internal
and external speakers. The internal speaker is being driven
by the TPA6203A1 (1.25W mono differential amplifier), while
the external speaker (hands-free set) is being driven by the
TPA6112A2 (150 mW stereo audio power amplifier).
NanoStar™ technology
is ideal for handheld
equipment where board
space is paramount!
A different portable application is depicted here with a
single analog switch. The analog switch is placed between
the audio power amplifier and audio hardware. The audio
amplifier chosen should not exceed the on-state switch
current of the analog switch, which is ±128 mA dc. In
comparison to Solution 1, power efficiency will not be as
optimal, and is expected from this low-cost solution.
Analog Switch 1
Internal Speaker
External Speaker
Hands-Free Set
Analog Switch 2
Voice –
Music –
Voice +
Music +
Mute*
Voice/Music Select
TPA6112A2
Texas Instruments
TPA6203A1
Texas Instruments
Solution 1
Analog Audio Routing
SPDT Analog Switches Add Flexibility to Your Design
This application clip focuses on several key applications where these devices bring added functionality to your design. The applications
include analog audio signal routing, power-up monitoring and memory sharing.
Solution 2
COM INH GND GND
VCC Y1
(NC)
Y2
(NO)
A
S
B2
(NO)
GND B1
(NC)
VCC A
Also Available in Pb-FREE
NanoFree.
LVC1G3157
or
LVC2G53
Analog Switch
Internal Speaker
External Speaker
32Ω
Hands-Free Set
Mute*
Speaker Select
Audio Power Amp
Texas Instruments
*The SN74LVC2G53 has the capability
to mute (place the outputs into high
impedance) the audio signal.
Only
7-Ω R
on
