BCM43455XKUBGT Datasheet, PDF (34/159 Pages) Cypress Semiconductor – Single-Chip 5G WiFi IEEE 802.11ac MAC/Baseband/ Radio with Integrated Bluetooth 4.1 and FM Receiver

BCM43455 Preliminary Data Sheet
External 32.768 kHz Low-Power Oscillator
External 32.768 kHz Low-Power Oscillator
The BCM43455 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 that meets the
requirements listed in Table 3.
Table 3: 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
Units
kHz
ppm
%
mV, p-p
–
Ω
pF
ppm
Broadcom^®
November 5, 2015 • 43455-DS109-R
BROADCOM CONFIDENTIAL
Page 33