zl30105 Zarlink Semiconductor, zl30105 Datasheet - Page 35

• Manufacturer Part Number: zl30105
• Description: Stratum 3 Redundant System Clock Synchronizer For T1/e1/sdh, Advanced Tca And H.110
• Manufacturer: Zarlink Semiconductor

6.3
The ZL30105 requires that the 3.3 V supply is not powered up after the 1.8 V supply. This is to prevent the risk of
latch-up due to the presence of parasitic diodes in the IO pads.
Two options are given:
1. Power up the 3.3 V supply fully first, then power up the1.8 V supply
2. Power up the 3.3 V supply and the 1.8 V supply simultaneously, ensuring that the 3.3 V supply is never lower
6.4
A simple power up reset circuit with about a 60 µs reset low time is shown in Figure 22. Resistor R
only and limits current into the RST pin during power down conditions. The reset low time is not critical but should
be greater than 300 ns.
than a few hundred millivolts below the 1.8 V supply (e.g., by using a schottky diode or controlled slew rate)
Power Up Sequence
Reset Circuit
ZL30105
Figure 22 - Power-Up Reset Circuit
RST
Zarlink Semiconductor Inc.
ZL30105
1 kΩ
R
35
P
10 kΩ
R
+3.3 V
10 nF
C
P
is for protection
Data Sheet