CC3120 Datasheet, PDF (18/57 Pages) Texas Instruments – SimpleLink Wi-Fi Wireless Network Processor Internet-of-Things Solution for MCU Applications

CC3120
SWAS034 – FEBRUARY 2017
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4.13 Timing and Switching Characteristics
4.13.1 Power Supply Sequencing
For proper operation of the CC3120R device, perform the recommended power-up sequencing as follows:
1. Tie VBAT (pins 37, 39, 44) and VIO (pins 54 and 10) together on the board.
2. Hold the RESET pin low while the supplies are ramping up. TI recommends using a simple RC circuit
(100 K ||, 1 µF, RC = 100 ms).
3. For an external RTC, ensure that the clock is stable before RESET is deasserted (high).
For timing diagrams, see Section 4.13.3.
4.13.2 Device Reset
When a device restart is required, the user may either issue a negative pulse on the nHIB pin (pin 2) or on
the nRESET pin (pin 32), keeping the other pulled high, depending on the configuration of the platform. In
case the nRESET pin is used, the user must follow one of the two alternatives to ensure the reset is
properly applied:
• A high-to-low reset pulse (on pin 32) of at least 200-mS duration
• If the above cannot be ensured, a pulldown resistor of 2M Ω should be connected to pin 32
(RTC_XTAL_N). If implemented, a shorter pulse of at least 100 uSec can be used.
To ensure a proper reset sequence, the user has to call the sl_stop function prior to toggling the reset.
4.13.3 Reset Timing
4.13.3.1 nRESET (32k XTAL)
Figure 4-6 shows the reset timing diagram for the 32k XTAL first-time power-up and reset removal.
T1
T2
T3
VBAT
VIO
nRESET
nHIB
STATE
POWER
OFF
RESET
HW INIT
FW INIT
Device Ready to
serve API calls
32-kHz
XTAL
Figure 4-6. First-Time Power-Up and Reset Removal Timing Diagram (32k XTAL)
Table 4-3 describes the timing requirements for the XTAL first-time power-up and reset removal.
ITEM
T1
T2
T3
Table 4-3. First-Time Power-Up and Reset Removal Timing Requirements (32k XTAL)
NAME
Supply settling time
Hardware wake-up time
Initialization time
DESCRIPTION
Depends on application board
power supply, decoupling
capacitor, and so on
32-kHz XTAL settling plus
firmware initialization time plus
radio calibration
MIN
TYP
MAX
UNIT
3
ms
25
ms
1.35
s
18
Specifications
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