BCM4354KKWBGT Datasheet, PDF (31/192 Pages) Cypress Semiconductor – Single-Chip 5G Wi-Fi IEEE 802.11ac 2×2 MAC/ Baseband/Radio with Integrated Bluetooth 4.1 and FM Receiver

BCM4354 Data Sheet
External 32.768 kHz Low-Power Oscillator
External 32.768 kHz Low-Power Oscillator
The BCM4354 uses a secondary low-frequency clock for Low-Power mode timing. Either the internal low-
precision LPO or an external 32.768 kHz precision oscillator is required. The internal LPO frequency range is
approximately 33 kHz (± 30%) over process, voltage, and temperature, which is adequate for some
applications. However, one trade-off caused by this wide LPO tolerance is a small current consumption increase
during power save mode that is incurred by the need to wake up earlier to avoid missing beacons.
Whenever possible, the preferred approach is to use a precision external 32.768 kHz clock which meets the
requirements listed in Table 4.
Table 4: External 32.768 kHz Sleep Clock Specifications
Parameter
Nominal input frequency
Frequency accuracy
Duty cycle
Input signal amplitude
Signal type
Input impedance^a
Clock jitter (during initial start-up)
a. When power is applied or switched off.
LPO Clock
32.768
±200
30–70
200-3300
Square-wave or sine-wave
> 100k
<5
< 10,000
Unit
kHz
ppm
%
mV, p-p
–
Ω
pF
ppm
Broadcom^®
October 15, 2014 • 4354-DS109-R
BROADCOM CONFIDENTIAL
Page 30