zl30108 Zarlink Semiconductor, zl30108 Datasheet - Page 20

• Manufacturer Part Number: zl30108
• Description: Sonet/sdh Network Interface Dpll
• Manufacturer: Zarlink Semiconductor

7.3
The ZL30108 requires that the 3.3 V is not powered after the 1.8 V. 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 3.3 V first, 1.8 V later
2. Power up 3.3 V and 1.8 V simultaneously ensuring that the 3.3 V power is never lower than 1.8 V minus a few
7.4
A simple power up reset circuit with about a 60 µs reset low time is shown in Figure 12. 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.
hundred millivolts (e.g., by using a schottky diode or controlled slew rate)
Power Up Sequence
Reset Circuit
ZL30108
Figure 12 - Power-Up Reset Circuit
RST
Zarlink Semiconductor Inc.
ZL30108
1 kΩ
R
20
P
10 kΩ
R
+3.3 V
10 nF
C
P
is for protection
Data Sheet