TMS570LS3137_12 Datasheet, PDF (61/159 Pages) Texas Instruments – TMS570LS3137 16/32-Bit RISC Flash Microcontroller

TMS570LS3137
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SPNS162. – SEPTEMBER 2011
4.6.1.2 Low Power Oscillator
The Low Power Oscillator (LPO) is comprised of two oscillators — HF LPO and LF LPO, in a single
macro.
4.6.1.2.1 Features
The main features of the LPO are:
• Supplies a clock at extremely low power for power-saving modes. This is connected as clock source #
4 of the Global Clock Module.
• Supplies a high-frequency clock for non-timing-critical systems. This is connected as clock source # 5
of the Global Clock Module.
• Provides a comparison clock for the crystal oscillator failure detection circuit.
BIAS_EN
LFEN
LF_TRIM
HFEN
HF_TRIM
Low
Power
Oscillator
CLK80K
CLK10M
CLK10M_VALID
nPORRST
Figure 4-5. LPO Block Diagram
Figure 4-5 shows a block diagram of the internal reference oscillator. This is a low power oscillator (LPO)
and provides two clock sources: one nominally 80KHz and one nominally 10MHz.
4.6.1.2.2 LPO Electrical and Timing Specifications
Parameter
LPO - HF oscillator
LPO - LF oscillator
Table 4-10. LPO Specifications
MIN
untrimmed frequency
5.5
startup time from STANDBY (LPO BIAS_EN High for
at least 900µs)
cold startup time
untrimmed frequency
36
startup time from STANDBY (LPO BIAS_EN High for
at least 900µs)
cold startup time
Type
9.6
85
MAX
19.5
10
900
180
100
2000
Unit
MHz
µs
µs
kHz
µs
µs
Copyright © 2011, Texas Instruments Incorporated
System Information and Electrical Specifications
61
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