zl30110 Zarlink Semiconductor, zl30110 Datasheet - Page 14

• Manufacturer Part Number: zl30110
• Description: Telecom Rate Conversion Dpll
• Manufacturer: Zarlink Semiconductor

6.3
The ZL30110 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 protection diodes in the IO pads.
Two options are given:
1. Power-up the 3.3 V supply fully first, then power up the 1.8 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
than a few hundred millivolts below the 1.8 V supply (e.g., by using a schottky diode or controlled slew rate)
6.4
A simple power up reset circuit with about a 60 µs reset low time is shown in Figure 6. 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.
Power Up Sequence
Reset Circuit
ZL30110
Figure 6 - Power-Up Reset Circuit
RST
Zarlink Semiconductor Inc.
ZL30110
1 kΩ
R
14
P
10 kΩ
R
+3.3 V
10 nF
C
P
is for protection
Data Sheet