LM4902LDBD National Semiconductor, LM4902LDBD Datasheet - Page 15
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LM4902LDBD
Manufacturer Part Number
LM4902LDBD
Description
BOARD EVALUATION LM4902LD
Manufacturer
National Semiconductor
Series
Boomer®r
Datasheet
1.LM4902MMNOPB.pdf
(18 pages)
Specifications of LM4902LDBD
Amplifier Type
Class AB
Output Type
1-Channel (Mono)
Max Output Power X Channels @ Load
675mW x 1 @ 8 Ohm
Voltage - Supply
2 V ~ 5.5 V
Operating Temperature
-40°C ~ 85°C
Board Type
Fully Populated
Utilized Ic / Part
LM4902
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Application Information
From Equation 5, the minimum A
Since the desired input impedance was 20 k , and with a
A
R
bandwidth requirements which must be stated as a pair of
−3 dB frequency points. Five times away from a pole gives
0.17 dB down from passband response which is better than
the required
As stated in the External Components section, R
junction with C
VD
i
= R
of 2, a ratio of 1:1 of R
F
= 20 k . The final design step is to address the
±
0.25 dB specified.
i
create a highpass filter.
f
H
R
f
= 20kHz x 5 = 100kHz
L
F
= 100Hz/5 = 20Hz
/R
i
= A
F
VD
to R
/2
VD
i
results in an allocation of
is 1.55; use A
(6)
(Continued)
VD
i
in con-
= 2.
15
The high frequency pole is determined by the product of the
desired high frequency pole, f
A
25MHz. This figure displays that if a designer has a need to
design an amplifier with a higher differential gain, the
LM4902 can still be used without running into bandwidth
problems.
= 100kHz which is much smaller than the LM4902 GBWP of
VD
. With a A
C
i
1/(2
VD
*
20 k
= 2 and f
*
20 Hz) = 0.397µF; use 0.39µF
H
= 100kHz, the resulting GBWP
H
, and the differential gain,
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