LM3S5739 Datasheet, PDF (246/856 Pages) Texas Instruments – Stellaris® LM3S5739 Microcontroller

Hibernation Module
resulting in a 32.768-kHz clock source. If a crystal is used for the clock source, the software must
leave a delay of t_{XOSC_SETTLE} after setting the CLK32EN bit and before any other accesses to the
Hibernation module registers. The delay allows the crystal to power up and stabilize. If an oscillator
is used for the clock source, no delay is needed.
Figure 6-2. Clock Source Using Crystal
Input
Voltage
Regulator
or Switch
IN OUT
EN
Stellaris Microcontroller
VDD
XOSC0
X₁
R_L
XOSC1
C₁
C₂
R_PU
Open drain
external wake
up circuit
HIB
WAKE
VBAT
GND
3V
Battery
Note:
X₁ = Crystal frequency is f_{XOSC_XTAL}.
C_1,2 = Capacitor value derived from crystal vendor load capacitance specifications.
R_L = Load resistor is R_{XOSC_LOAD}.
R_PU = Pull-up resistor (1 M½).
See “Hibernation Module” on page 799 for specific parameter values.
Figure 6-3. Clock Source Using Dedicated Oscillator
Input
Voltage
Regulator
or Switch
IN OUT
EN
Clock
Source
(f_{EXT_OSC})
N.C.
Stellaris Microcontroller
VDD
XOSC0
XOSC1
R_PU
Open drain
external wake
up circuit
HIB
WAKE
VBAT
GND
Note: R_PU = Pull-up resistor (1 M½).
3V
Battery
246
November 17, 2011
Texas Instruments-Production Data