Low-Frequency, High-Gain Mode; Low-Frequency, Low-Power Mode - NXP Semiconductors freescale KV4 Series Reference Manual

Table of Contents

Functional Description

High-frequency mode1, high-gain

High-frequency mode1, low-power

High-frequency mode2, high-gain

High-frequency mode2, low-power

For information about low power modes of operation used in

this chip and their alignment with some OSC modes, see the

chip's Power Management details.

29.8.2.1 Low-Frequency, High-Gain Mode

In Low-frequency, high-gain mode, the oscillator uses a simple inverter-style amplifier.

The gain is set to achieve rail-to-rail oscillation amplitudes.

The oscillator input buffer in this mode is single-ended. It provides low pass frequency

filtering as well as hysteresis for voltage filtering and converts the output to logic levels.

In this mode, the internal capacitors could be used.

In low-frequency, low-power mode, the oscillator uses a gain control loop to minimize

power consumption. As the oscillation amplitude increases, the amplifier current is

reduced. This continues until a desired amplitude is achieved at steady-state. This mode

provides low pass frequency filtering as well as hysteresis for voltage filtering and

converts the output to logic levels. In this mode, the internal capacitors could be used, the

internal feedback resistor is connected, and no external resistor should be used.

In this mode, the amplifier inputs, gain-control input, and input buffer input are all

capacitively coupled for leakage tolerance (not sensitive to the DC level of EXTAL).

Also in this mode, all external components except for the resonator itself are integrated,

which includes the load capacitors and feeback resistor that biases EXTAL.

Table 29-6. Oscillator modes (continued)

KV4x Reference Manual, Rev. 2, 02/2015

Frequency Range

(3 MHz) up to f

(8 MHz) up to f

Freescale Semiconductor, Inc.