le9502 Zarlink Semiconductor, le9502 Datasheet - Page 7

• Manufacturer Part Number: le9502
• Description: Ringing Subscriber Line Interface Circuit
• Manufacturer: Zarlink Semiconductor

Note:
* Denotes external components.
** Generated internally by band gap ≅ 1.4 V.
*** V
**** Preferably, the external clock should be Low in startup. For a system (codec) which has a high impedance at the clock output in start up, the
additional R
RING
in active
in ringing
I
I
= V
800K
800K
Base
C
8
8
R
V
V
HSi
SET
RINGP
*
*
and R
CHS
ISET
- V
i
RINGM
BG
V
resistors are recommended with values of 10 kΩ and 100 kΩ respectively.
CC
800 k
100
800K
48 V
800K
V
Ref. Current
Generator
REF
V
RING
CLAMP
1.4 V
***
in ringing
in active
Figure 6. Switching Power Supply Block Diagram
COMPARATOR
+
-
OUTPUT
Zarlink Semiconductor Inc.
RESET
LATCH
internal clock
square wave converter
SET
7
BLANKING
LEADING
FILTER
DRIVER
EDGE
V
SW
0.28
+
-
VRAMP
V
VREG
C
+
VSW
RAMP
ILS
SD
i
i
i
*
R
C
C
I
R
LIMi
BDi
RAMP
VREGi
BDi
*
*
L
*
Q
SWi
V
*
RAMP
+
SW
D
*
C
Di
*
VREGii
BGND
*
10% High Duty Cycle
L
R
external clock ****
VREGi
+
Base
C
*
CSWi
D
Q
*
85 kHz
*
SWi
SWi
*
*
*
C
+
C
R
SWi
C
BG
ESRi
FLi
*
*
*
*