MH88612K
and reduced by the current limit circuit to a lower
value to protect the internal circuitry.
Preliminary Information
subscriber loop. A logic high input applied to the
power denial pin effectively removes the battery
voltage from the loop driver circuitry. The resulting
I
Loop
is negligible and power consumption is
minimised. The power denial function is useful for
disabling a loop which may have a ground fault. This
pin should be held low when not in use.
Receive Gain
The power denial function is a feature of the
MH88612C which allows for powering down of the
Applications
Component List
R1
= 1/4 W, + 10%, 200Ω
R2
= 1/4 W, + 5%, 470Ω
C1
= Cap. elec., 1.0µF, + 10%, 25V
D1,D2,D3,D4 = Diode Rect., 200V, 1A, IN4003
K1
= Relay E/M, 5 or 6V, 1 form C
Decoupling capacitors (Cap. Cer 0.1µF, 50% + 20%) should be added to V
DD
, V
EE
, V
Bat
, V
Ref
and V
RLY
Options RV1, RV2 = 160V Vrms, 250V, 10J
90 VRMS
SUPERIMPOSED
ON -48VDC
R1
K1
VBat
MH88612K
RF
VR
RV
D4
D1
D2
VX
TF
D3
VRef
VBat
Tip
RV1
TIP
SHK
RV2
Ring
RING
RC2
RC1
PD
+5V
K1
VRLY
C1
RD1
VBat VDD
VEE
CAP
-
GNDA
+
R2
Ring Trip
Filter
Control
-48V +5V
-5V
Figure 3 - Application Circuit
2-124
MITEL [ MITEL NETWORKS CORPORATION ]
