AD1847JP Analog Devices Inc, AD1847JP Datasheet - Page 24

• Manufacturer Part Number: AD1847JP
• Manufacturer: Analog Devices Inc

Specifications of AD1847JP

• Single Supply Voltage (typ): 5V
• Single Supply Voltage (min): 4.75V
• Single Supply Voltage (max): 5.25V
• Package Type: PLCC
• Lead Free Status / RoHS Status: Not Compliant

AD1847
Circuits for 2 V
Figure 14 and Figure 15. Note that these are divide-by-two
resistive dividers. The input resistor and 560 pF (1000 pF)
capacitor provide the single-pole of antialias filtering required
for the ADCs. If line-level inputs are already at the 1 V
expected by the AD1847, the resistors in parallel with the
560 pF (1000 pF) capacitors can be omitted. If the application
does not route the AUX2 inputs to the ADCs, then no antialias
filtering is required (only the 1 F ac coupling capacitor).
Figure 16 illustrates one example of how an electret condenser
microphone requiring phantom power could be connected to
the AD1847. V
like a 2N4124 will also work well for this purpose. Note that if a
battery-powered microphone is used, the buffer and R2s are not
needed. The values of R1, R2, and C should be chosen in light
of the mic characteristics and intended gain. Typical values for
these might be R1 = 20 k , R2 = 2 k , and C = 220 pF.
Figure 16. “Phantom-Powered” Microphone Input Circuit
Figure 15. 2 V
Figure 14. 2 V
MICROPHONE
MICROPHONE
CONDENSER
CONDENSER
ELECTRET
ELECTRET
INPUT
RIGHT
INPUT
LEFT
REF
rms
rms
rms
1000pF
1000pF
3.3k
3.3k
5.1k
560pF
5.1k
560pF
R2
R2
line-level inputs and auxiliaries are shown in
is shown buffered by an op amp; a transistor
1 F
1 F
NPO
NPO
NPO
NPO
Line-Level Input Circuit for AUX Inputs
Line-Level Input Circuit for Line Inputs
5k
5k
1/2 SSM2135
OR AD820
4.3k
4.3k
5.1k
5.1k
R1
R1
C
C
0.33 F
0.33 F
1/2 SSM2135
1/2 SSM2135
1 F
1 F
OR AD820
OR AD820
L_LINE1
L_LINE2
R_LINE1
R_LINE2
L_AUX1
L_AUX2
R_AUX1
R_AUX2
0.33 F
0.33 F
V
R_LINE1
R_LINE2
L_LINE1
L_LINE2
V
REF
REF
rms
levels
–24–
Figure 17 shows ac-coupled line outputs. The resistors are
used to center the output signals around analog ground. If
dc-coupling is desired, V
mentioned previously.
A circuit for headphone drive is illustrated in Figure 18. Drive is
supplied by +5 V operational amps. The circuit shown ac
couples the headphones to the line output.
Figure 19 illustrates reference bypassing. V
connected to its bypass capacitors.
Figure 20 illustrates signal-path filtering capacitors, L_FILT
and R_FILT. The AD1847 must use 1.0 F capacitors. The
1.0 F capacitors required by the AD1847 can be of any type.
Figure 20. External Filter Capacitor Connections
R_OUT
L_OUT
V
REF
Figure 18. Headphone Drive Connections
V
Figure 19. Voltage Reference Bypassing
REFI
L_OUT
R_OUT
Figure 17. Line Output Connections
10 F
20k
20k
1.0 F
REF
LFILT
1 F
could be used with op amps as
1 F
0.1 F
SSM2135
18k
18k
RFILT
V
1.0 F
470 F
470 F
REF
47k
47k
REFI
HEADPHONE
RIGHT
HEADPHONE
LEFT
should only be
10 F
REV. B