DS1077

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OVERVIEW

A block diagram of the DS1077 is shown in Figure 1. The DS1077 consists of four major components:

1) Internal Master Oscillator, 2) Prescalers, 3) Programmable Divider, and 4) Control Registers.

The internal oscillator is factory-trimmed to provide a master frequency (Master CLK) that can be routed

directly to the outputs (OUT0 & OUT1) or through separate prescalers (P0 & P1). OUT1 can also be

routed through an additional divider (N).

The Prescaler (P0) divides the Master Clock by 1, 2, 4, or 8 to be routed directly to the OUT0 pin.

The Prescaler (P1) divides the Master Clock by 1, 2, 4, or 8, which can be routed directly to the OUT1 pin

or to the Divider (N) input, which is then routed to the OUT1 pin.

The Programmable Divider (N) divides the Prescaler Output (P1) by any number selected between 2 and

1025 to provide the Main Output (OUT1) or it can be bypassed altogether by use of the DIV1 register bit.

The value of N is stored in the DIV register.

The Control Registers are user-programmable through a 2-wire serial interface to determine operating

frequency (values of P0, P1, & N) and modes of operation. The register values are stored in EEPROM

and therefore only need to be programmed to alter frequencies and operating modes.

PIN DESCRIPTIONS

Output 1 (OUT1)—This pin is the main oscillator output; its frequency is determined by the control

register settings for the prescaler P1 (mode bits 1M1 & 1M0) and divider N (DIV word).

Output 0 (OUT0)—A reference output, OUT0, is taken from the output of the reference select Mux. Its

frequency is determined by the control register settings for CTRL0 and values of Prescaler P0 (mode bits

0M1 & 0M0) (see Table 1).

Control Pin 0 (CTRL0)—A multifunctional input pin that can be selected as a MUX SELECT,

OUTPUT ENABLE and/or a POWER-DOWN. Its function is determined by the user-programmable

control register values EN0, SEL0, and PDN0 (see Table 1).

Control Pin 1 (CTRL1)—A multifunctional input pin that can be selected as a OUTPUT ENABLE

and/or a POWER-DOWN. Its function is determined by the user-programmable control register value of

PDN1 (see Table 2).

Serial Data Input/Output (SDA)—Input/Output pin for the 2-wire serial interface used for data transfer.

Serial Clock Input (SCL)—Input pin for the 2-wire serial interface used to synchronize data movement

on the serial interface.