ZL30110
Data Sheet
5.3 Power Up Sequence
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)
5.4 Reset Circuit
A simple power up reset circuit with about a 60 µs reset low time is shown in Figure 6. Resistor RP is for protection
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.
ZL30110
+3.3 V
R
10 kΩ
RST
C
10 nF
RP
1 kΩ
Figure 6 - Power-Up Reset Circuit
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Zarlink Semiconductor Inc.
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
