
LD511 - HYB DATA SHEET
L
Doc.No.22978-3 [Rev. May 2003]
1 of 6
FEATURES
64dB typical electrical gain
0.94V
DC
voltage regulator
7ms attack time, 40ms release time
15dB threshold adjustment
low noise and distortion
compression ratio
∞
: 1
0.3kHz – 6kHz frequency response
STANDARD PACKAGING
Hybrid Typical Dimensions:
0.0945
×
0.1115
×
0.042in
(2.40
×
2.83
×
1.07mm)
DESCRIPTION
The LD511 is a Class A compression amplifier which can
operate over a range of DC battery voltages from 1.1V
to 2.4V. A voltage regulator, which is independent of
supply voltage variations, is on-chip to supply a stable
0.94V
DC
bias to the amplifier circuitry and to the
microphone.
The LD511, in compression, has approximately 15dB of
threshold adjustment by varying
R
TH
(see application
circuit) and a compression function ratio of
∞
: 1.
Minimum attack and release times are fixed at 7ms and
40ms respectively and they can be adjusted simultaneously
by changing the filter capacitor on pin 8, although the ratio
of attack to release time is kept constant.
The output stage bias can be set to accommodate different
receiver impedances by changing the value of
R
E
. The
voltage across
R
E
(pin 2 to ground) is a constant 27mV so
the bias current is 27mV divided by the total value of
R
E
in
parallel with 500
.
All resistors in ohms, all capacitors in farads unless otherwise stated.
BLOCK DIAGRAM
VOLTAGE
REGULATOR
10K
35K
RECTIFIER
BOUT
AGC
GND
C
AGC
AIN
V
REG
AOUT
10
BIN
1
VB
6
20K
R
E
- B
- A
R
IN
R
E
7
9
8
4
2
5
3
Class A
Compression Amplifier