CP3BT10 Datasheet, PDF (72/210 Pages) National Semiconductor (TI) – Reprogrammable Connectivity Processor with Bluetooth and USB Interfaces

15.3 LMX5251 POWER-UP SEQUENCE
15.4 LMX5252 POWER-UP SEQUENCE
To power-up a Bluetooth system based on the CP3BT10
and LMX5251 devices, the following sequence must be per-
formed:
1. Apply VDD to the LMX5251.
2. Apply IOVCC and VCC to the CP3BT10.
3. Drive the RESET# pin of the LMX5251 high a minimum
of 2 ms after the LMX5251 and CP3000 supply rails are
powered up. This resets the LMX5251 and CP3BT10.
4. After internal Power-On Reset (POR) of the CP3BT10,
the RFDATA pin is driven high. The RFCE, RFSYNC,
and SDAT pins are in TRI-STATE mode. Internal pull-
up/pull-down resistors on the CCB_CLOCK (SCLK),
CCB_DATA (SDAT), CCB_LATCH (SLE), and
TX_RX_SYNC (RFSYNC) inputs of the LMX5251 pull
these signals to states required during the power-up
sequence.
5. When the RFDATA pin is driven high, the LMX5251 en-
ables its oscillator. After an oscillator start-up delay, the
LMX5251 drives a stable 12-MHz BBP_CLOCK
(BBCLK) to the CP3BT10.
6. The Bluetooth baseband processor on the CP3BT10
now directly controls the RF interface pins and drives
the logic levels required during the power-up phase.
When the RFCE pin is driven high, the LMX5251
switches from “power-up” to “normal” mode and dis-
ables the internal pull-up/pull-down resistors on its RF
interface inputs.
7. In “normal” mode, the oscillator of the LMX5251 is con-
trolled by the RFCE signal. Driving RFCE high enables
the oscillator, and the LMX5251 drives its BBP_CLOCK
(BBCLK) output.
A Bluetooth system based on the CP3BT10 and LMX5252
devices has the following states:
„ Off—When the LMX5252 enters Off mode, all configura-
tion data is lost. In this state, the LMX5252 drives BPOR
low.
„ Power-Up—When the power supply is on and the
LMX5252 RESET# input is high, the LMX5252 starts up
its crystal oscillator and enters Power-Up mode. After the
crystal oscillator is settled, the LMX5252 sends four
clock cycles on BRCLK (BBCLK) before driving BPOR
high.
„ RF Init—The baseband controller on the CP3BT10 now
drives RFCE high and takes control of the crystal oscilla-
tor. The baseband performs all the needed initialization
(such as writing the registers in the LMX5252 and crystal
oscillator trim).
„ Idle—The baseband controller on the CP3BT10 drives
RFDATA low when the initialization is ready. The
LMX5252 is now ready to start transmitting, receiving, or
enter Sleep mode.
„ Sleep—The LMX5252 can be forced into Sleep mode at
any time by driving RFCE low. All configuration settings
are kept, only the Bluetooth low power clock is running
(B3k2).
„ Wait XTL—When RFCE goes high, the crystal oscillator
becomes operational. When it is stable, the LMX5252
enters Idle mode and drives BRCLK (BBCLK).
Any State
RESET# = Low or
Power is cycled
VDD_LMX5251
VCC_CP3000
IOVCC_CP3000
RESET#_LMX5251
RESET_CP3000
RFCE
BBCLK
t_PTOR
Low
Low
High
RFDATA
RFSYNC
SDAT
High
Low
Low
SCLK
Low
SLE
LMX5251 CP3000 LMX5251
Oscillator Initialization Initialization
Start-Up
Standby
Active
LMX5251 in
Power-Up Mode
LMX5251 in Normal Mode
DS016
Figure 21. LMX5251 Power-Up Sequence
Wait for
Crystal Osc.
To Stabilize
Off
RESET# = High and
Power is On
Power-Up
Crystal Osc. Stable
Any State
After RF Init
RFCE = Low
Sleep
RFCE = High
RFCE = High
RFDATA = Don't Care
Write Registers
RF Init
Wait for
Crystal Osc.
To Stabilize
Wait XTL
Crystal Osc. Stable
Idle
DS324
Figure 22. LMX5252 Power States
The power-up sequence for a Bluetooth system based on
the CP3BT10 and LMX5252 devices is shown in Figure 23.
www.national.com
72