Detailed Description

The MAX7383 is a dual-speed clock generator for

microcontrollers (µCs) and UARTs in 3V, 3.3V, and 5V

applications. The MAX7383 is a replacement for two

crystal-oscillator modules, crystals, or ceramic res-

onators. The high-speed clock frequency is factory

trimmed to specific values. A variety of popular stan-

dard frequencies are available. The low-speed clock

nal components are required for setting or adjusting the

frequency.

Oscillator

The push-pull clock output drives a load to within

400mV of either supply rail. The clock output remains

stable over the full operating voltage range and does

not generate short output cycles during either power-on

or changing of the frequency. A typical oscillating start-

up is shown in the Typical Operating Characteristics.

Clock-Speed Selection

Drive SPEED low to select slow clock speed (nominally

32.768kHz) or high to select full clock speed. SPEED can

clock speed, or connected to a logic output (such as a

µP GPIO port) used to change clock speed on the fly. If

SPEED is connected to a µP GPIO port, connect a pullup

or pulldown resistor to set the clock to the preferred

speed on power-up. SPEED input bias current is 2µA

max, so a resistor value as high as 500k

Ω can be used.

Applications Information

Interfacing to a Microcontroller

Clock Input

The MAX7383 clock output is a push-pull, CMOS, logic

output that directly drives a µP or µC clock input. There

are no impedance-matching issues when using the

MAX7383. Refer to the microcontroller data sheet for

clock input compatibility with external clock signals.

The MAX7383 requires no biasing components or load

capacitance. When using the MAX7383 to retrofit a

crystal oscillator, remove all biasing components from

the oscillator input.

Output Jitter

The MAX7383’s jitter performance is given in the

Electrical Characteristics table as a peak-to-peak value

obtained by observing the output of the MAX7383 for

20s with a 12GHz oscilloscope. Jitter measurements

are approximately proportional to the period of the out-

put of the device. Thus, a 10MHz device has approxi-

mately twice the jitter value of a 20MHz device. The

jitter performance of all clock sources degrades in the

presence of mechanical and electrical interference.

The MAX7383 is relatively immune to vibration, shock,

and EMI influences and thus provides a considerably

Silicon Oscillator with Low-Power

Frequency Switching

6

_______________________________________________________________________________________

MAX7383

CLOCK

10MHz TO

32MHz

(HF OSCILLATOR)

UVLO

GND

32kHz

(LF OSCILLATOR)

LOGIC

MUX

SPEED

Figure 1. Functional Diagram

SUFFIX

STANDARD FREQUENCY (MHz)

UK

10

UT

11.0592

VB

12

VT

14.7456

WB

16

YN

32

Table 1. Standard Frequencies

For all other frequency options, contact factory.

PART

FREQUENCY

(MHz)

TOP MARK

MAX7383AXUK

10

AEVN

MAX7383AXUT

11.0592

AEVO

MAX7383AXVB

12

AEVP

MAX7383AXVT

14.7456

AEVQ

MAX7383AXWB

16

AEVT

MAX7383AXYN*

32

AEVS

Table 2. Standard Part Numbers

*Contact factory for availability.