BCM89071A1CUBXGT Datasheet, PDF (55/69 Pages) Cypress Semiconductor – Single-Chip Automotive Grade Bluetooth Transceiver and Baseband Processor

BCM89071 Data Sheet
Timing and AC Characteristics
Timing and AC Characteristics
In this section, use the numbers listed in the reference column to interpret the timing diagrams.
Startup Timing
There are two basic startup scenarios. In one scenario, the chip startup and firmware boot is held off while the
RST_N pin is asserted. In the second scenario, the chip startup and firmware boot is directly triggered by the
chip power-up. In this case, an internal power-on reset (POR) is held for a few ms, after which the chip
commences startup.
The global reset signal in the BCM89071 is a logical OR (actually a wired AND, since the signals are active low)
of the RST_N input and the internal POR signals. The last signal to be released determines the time at which
the chip is released from reset. The POR is typically asserted for 3 ms after VDDC crosses the 0.8V threshold,
but it may be as soon as 1.5 ms after this event.
After the chip is released from reset, the both startup scenarios follow the same sequence, as follows:
2. After approximately 120 s, the CLK_REQ (GPIO_5) signal is asserted.
3. The chip remains in sleep state for a minimum of 4.2 ms.
4. If present, the TCXO and LPO clocks must be oscillating by the end of the 4.2 ms period.
If a TCXO clock is not in the system, a crystal is assumed to be present at the XIN and XOUT pins. If an LPO
clock is not used, the firmware will detect the absence of a clock at the LPO_IN lead and use the internal LPO
clock instead.
Figure 9 and Figure 10 on page 55 illustrate the two startup timing scenarios.
Figure 9: Startup Timing from RST_N
VDDIO, VBAT,REG_EN*
t_rampmax = 200 μs
VREG
VDDC > 0.8V
t = 300μs
RST_N
GPIO5 (CLK_REQ)
TCXO
LPO
t =64 to 171 μs
tmax = 4.2 ms
Broadcom^®
April 16, 2015 • 89071-DS106-R
Baseband Transceiver and Baseband Processor
Page 54