FUNCTIONAL DEVICE OPERATION
CLOCK GENERATION AND REAL TIME CLOCK
Figure 10. SRTC block diagram
VSRTC
The VSRTC regulator provides the CLK32KMCU output level. It is also used to bias the Low Power SRTC domain of the SRTC
module integrated on certain FSL processors. The VSRTC regulator is enabled as soon as the RTCPORB is detected. The
VSRTC cannot be disabled.
Table 17. VSRTC Specifications
Parameter
Condition
Min
Typ
Max
Units
General
1.8
-
-
3.6
V
V
Operating Input Voltage Range,
VINMIN to VINMAX
Valid Coin Cell range or valid BP
UVDET
4.65
Operating Current Load Range ILMIN
to ILMAX
0
-
-
50
-
μA
μF
Bypass Capacitor Value
1.0
Active Mode - DC
VINMIN < VIN < VINMAX
ILMIN < IL < ILMAX
Output Voltage VOUT
1.150
1.20
1.25
V
REAL TIME CLOCK
A real Time Clock (RTC) function is provided including time and day counters as well as an alarm function. The utilizes a
32 kHz clock, either the RC oscillator or the 32.768 kHz crystal oscillator as a time base, and is powered by the coin cell backup
supply when BP has dropped below operational range. In configurations where the SRTC is used, the RTC can be disabled to
conserve current drain by setting the RTCDIS bit to a 1 (defaults on at power up).
TIME AND DAY COUNTERS
The 32 kHz clock is divided down to a 1.0 Hz time tick which drives a 17 bit Time Of Day (TOD) counter. The TOD counter
counts the seconds during a 24 hour period from 0 to 86,399, and will then roll over to 0. When the roll over occurs, it increments
the 15 bit DAY counter. The DAY counter can count up to 32767 days. The 1.0 Hz time tick can be used to generate a 1HZI
interrupt if unmasked.
13892
Analog Integrated Circuit Device Data
52
Freescale Semiconductor
FREESCALE [ Freescale ]
