MH88422(1995) Ver la hoja de datos (PDF) - Mitel Networks
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MH88422 Datasheet PDF : 12 Pages
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MH88422
Preliminary Information
TIP
D1
RING
14
MH88422
TIP
13
RLS
6
VX
7
VR
11
C2
10
TF
TXIN
4
RVLC
9
RING
VDD
3
LC
AGND
1
2
+
C1
+5V
Audio Output
Audio Input
Ring Voltage & Loop
Current Detect Output
Loop Control Input
NOTES:
Calls are set up and cleared in this mode by the
external controller. It turns on the loop via Loop
Control, dialling by pulsing loop control (or via
DTMF tones) and clearing down by turning Loop
Control off.
1) C1: 10µF, 6V Tantalum
2) C2: 0.1µF, 250V (Typical Value)
3) D1: 180VDC Foldback Diode, e.g. TISP4180, TISP5180
4) VX and VR are biased at 2.5V, therefore, coupling capacitors
may be required depending on application.
Figure 3 - Typical Application Circuit
TIP
RING
Line
Relay
Input
R6
K1a
D1
K1
14
TIP
13
RLS
11
TF
MH88422
6
VX
R2
Internal
dummy
Ringer
Resistor
7
VR
4
RVLC
9
RING
10
K1b
C2
TXIN
VDD
3
LC
AGND
1
2
+
Audio Output
Audio Input
Ring Voltage & Loop
Current Detect Output
Loop Control Input
C1
1) C1: 10µF, 6V Tantalum
+5V
2) C2: 0.47µF, 100V
K1b
3) D1: 180VDC Foldback Diode, e.g. TISP4180, TISP5180
4) VX and VR are biased at 2.5V, therefore, coupling capacitors
may be required depending on application.
5) R6 adjust the monitor phone detect sensitivity typically set to 200 ohms for 5mA limit on the
-1 variant and 75 ohms on the -3 variant.
6) K1b is added to remove the dummy ringer when using a combined phone on the-1 variant
NOTES:
and is not required for all other variants.
R2 & C2 form a dummy ringer, where R2 is on the hybrid and C2 must be fitted by the customer.
To initate a manual call, lift the handset. The RVLC pin will indicate that the line has been seized by the monitor phone.
The required number is then dialled and the connections established. During this phase the Loop Control
input should be turned ON to ensure that when the relay K1 is operated and the monitor phone removed from the line loop
current is still maintained. On receipt of the correct progress tones the external controller should control the data transmission
and clear down the call when it is completed by turning the Loop Control OFF. For applications in some countries such as
Germany the MH88422 can not be used with an optional telephone but may still be used in a combined telephone/fax machine.
Figure 4 - Typical Application Circuit with Dummy Ringer and Monitor Phone
2-28
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