Datasheet SY89429A Datasheet (MICREL)

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Page 1

PROGRAMMABLE

FREQUENCY SYNTHESIZER (25MHz to 400MHz)

ClockWorks™

SY89429A

FEATURES

■ Improved jitter performance over SY89429

■ 25MHz to 400MHz differential PECL outputs

■ ±25ps peak-to-peak output jitter

■ Minimal frequency over-shoot

■ Synthesized architecture

■ Serial 3 wire interface

■ Parallel interface for power-on

■ Internal quartz reference oscillator driven by quartz

crystal or PECL source

■ PECL output can operate with either +3.3V or +5V

VCC_OUT power supply

■ External loop filter optimizes performance/cost

■ Applications note (AN-06) for ease of design-ins

■ Available in PLCC and SOIC 28-pin packages

PIN CONFIGURATION

_CLOCK

S_DAT S_LOA

VCC_QUIE

LOOP _FILTER

LOOP_REF

XTAL1

CC_OUT

FOUT

25 24 23 22 21 20 19 26 27

1 2 3 4

TOP VIEW

567891011

VCC1

XTAL2

FOUT

PLCC

_LOAD

GND

M[0]

CC (TTL)

M[1]

TEST

GND (TTL)

M[3]

M[2]

N[1]

N[0]

M[8]

M[7]

M[6]

M[5]

M[4]

APPLICATIONS

■ Workstations

■ Advanced communications

■ High end consumer

■ High-performance computing

■ RISC CPU clock

■ Graphics pixel clock

■ Test equipment

■ Other high-performance processor-based

applications

DESCRIPTION

The SY89429A is a general purpose, synthesized clock source targeting applications that require both serial and parallel interfaces. Its internal VCO will operate over a range of frequencies from 400MHz to 800MHz. The differential PECL output can be configured to be the VCO frequency divided by 2, 4, 8 or 16. With the output configured to divide the VCO frequency by 2, and with a 16MHz external quartz crystal used to provide the reference frequency, the output frequency can be specified in 1MHz steps.

M[0] M[1]

M[2] M[3] M[4] M[5] M[6] M[7] M[8] N[0] N[1]

GND (TTL)

TEST

(TTL)

TOP VIEW

SOIC

Z28-1

_LOAD

CC1

XTAL

LOOP

_REF

LOOP

_FILTER

CC_QUIET

_LOAD

_DATA

_CLOCK

CC_OUT

FOUT

GND

Rev.: H Amendment: /0

Issue Date: October, 1998

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BLOCK DIAGRAM

ClockWorks™

SY89429A

+5.0V

÷ 8

10-25MHz

Fundamental

Crystal

OSC

PECL

Source

3 WIRE

INTERFACE

DETAILED BLOCK DIAGRAM

LOOP_FILTER

REF

PHASE DETECTOR

PLL

VCO

PECL

÷ M

400 – 800

÷ N

MHz

SERIAL

PARALLEL

INTERFACE

LOGIC

CONFIG INFO

+5.0V

23 1

LOOP_REF

CC_QUIET

+5.0V

CC1

FOUT

TEST

6, 21

÷ 8

10–25MHz

Fundamental

Crystal

PECL

Source

LOAD

DATA

CLOCK

XTAL1

OSC

XTAL2

NOTE:

Pin numbers reference PLCC pinout.

FREF

PHASE DETECTOR

COUNTER

L = LATCH H = Transparent

9-BIT SR

8 -> 16

400-800

VCO

9-BIT ÷ M

LATCH LATCH

M[8:0]

MHz

T110

(2,4,8,16)

2-BIT SR

17,18

÷ N

N[1:0]

+5.0V

CC_OUT

÷ M — LOW —

FOUT —

÷ M —

FREF —

HIGH —

7 6 5 4 3 2 1 0

FOUT ÷ 4 —

CLOCK

LATCH

3-BIT SR

19,22

FOUT

TEST

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PIN DESCRIPTIONS

ClockWorks™

SY89429A

INPUTS

XTAL1, XTAL2

These pins form an oscillator when connected to an external crystal. The crystal is series resonant. Alternatively, these pins can be driven with 100K PECL level by an external source.

S_LOAD

This TTL pin loads the configuration latches with the contents of the shift registers. The latches will be transparent when this signal is HIGH; thus, the register data must be stable on the HIGH-to-LOW transition of S_LOAD for proper operation.

S_DATA

This TTL pin is the input to the serial configuration shift registers.

S_CLOCK

This TTL pin clocks the serial configuration shift registers. On the rising edge of this signal, data from S_DATA is sampled.

P_LOAD

This TTL pin loads the configuration latches with the contents of the parallel inputs. The latches will be transparent when this signal is LOW; thus, the parallel data must be stable on the LOW-to-HIGH transition of P_LOAD for proper operation.

OUTPUTS

FOUT, FOUT

These differential positive-referenced ECL signals (PECL) are the output of the synthesizer.

TEST

The function of this TTL output is determined by the serial configuration bits T[2:0].

POWER VCC1

This is the positive supply for the chip and is normally connected to +5.0V.

VCC_OUT

This is the positive reference for the PECL outputs, FOUT and FOUT. It is constrained to be less than or equal to VCC1.

VCC_QUIET

This is the positive supply for the PLL and should be as noisefree as possible for low-jitter operation.

GND

These pins are the negative supply for the chip and are normally all connected to ground.

M[8:0]

These TTL pins are used to configure the PLL loop divider. They are sampled on the LOW-to-HIGH transition of P_LOAD. M[8] is the MSB, M[0] is the LSB. The binary count on the M pins equates to the divide-by value for the PLL.

N[1:0]

These TTL pins are used to configure the output divider modulus. They are sampled on the LOW-to-HIGH transition of P_LOAD.

N[1:0] Output Division

0 0 2 0 1 4 1 0 8 1 1 16

OTHER

LOOP_FILTER

This is an analog I/O pin that provides the loop filter for the PLL.

LOOP_REF

This is an analog I/O pin that provides a reference voltage for the PLL.

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ClockWorks™

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SY89429A

WITH 16MHZ INPUT

VCO Frequency 256 128 64 32 16 8421

(MHz) M Count M8 M7 M6 M5 M4 M3 M2 M1 M0

400 200 011001000 402 201 011001001 404 202 011001010 406 203 011001011

• • •••••••••

794 397 110001101 796 398 110001110 798 399 110001111 800 400 110010000

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

VCC Power Supply Voltage –0.5 to +7.0 V VI Input Voltage –0.5 to +7.0 V I

OUT Output Source Continuous 50 mA

Tstore Storage Temperature –65 to +150 °C

A Operating Temperature –0 to +75 °C

NOTE:

1. Permanent device damage may occur if ABSOLUTE MAXIMUM RATINGS are exceeded. This is a stress rating only and functional operation is not implied at conditions other than those detailed in the operational sections of this data sheet. Exposure to ABSOLUTE MAXIMUM RATlNG conditions for extended periods may affect device reliability.

(1)

Surge 100

FUNCTIONAL DESCRIPTION

The internal oscillator uses the external quartz crystal as the basis of its frequency reference. The output of the reference oscillator is divided by eight before being sent to the phase detector. With a 16MHz crystal, this provides a reference frequency of 2MHz.

The VCO within the PLL operates over a range of 400– 800MHz. Its output is scaled by a divider that is configured by either the serial or parallel interfaces. The output of this loop divider is also applied to the phase detector.

The phase detector and loop filter force the VCO output frequency to be M times the reference frequency by adjusting the VCO control voltage. Note that for some values of M (either too high or too low) the PLL will not achieve loop lock. External loop filter components are utilized to allow for optimal phase jitter performance.

The output of the VCO is also passed through an output divider before being sent to the PECL output driver. The output divider is configured through either the serial or the parallel interfaces and can provide one of four divider ratios (2, 4, 8 or 16). This divider extends the performance of the part while providing a 50% duty cycle.

The output driver is driven differentially from the output divider and is capable of driving a pair of transmission lines terminated

in 50Ω. The positive reference for the output driver is provided by a dedicated power pin (VCC_OUT) to reduce noise and provide application flexibility.

The configuration logic has two sections: serial and parallel. The parallel interface uses the values at the M[8:0] and N[1:0] inputs to configure the internal counters. Normally upon system reset, the P_LOAD input is held LOW until sometime after power becomes valid. With S_LOAD held LOW, on the LOWto-HIGH transition of P_LOAD, the parallel inputs are captured. The parallel interface has priority over the serial interface. Internal pull-up resistors are provided on the M[8:0] and N[1:0] inputs to reduce component count.

The serial interface logic is implemented with a 14-bit shift register scheme. The register shifts once per rising edge of the S_CLOCK input. The serial input S_DATA must meet set-up and hold timing as specified in the AC parameters section of this data sheet. With P_LOAD held HIGH, the configuration latches will capture the value in the shift register on the HIGH-to-LOW edge of the S_LOAD input. See the programming section for more information.

The TEST output reflects various internal node values and is controlled by the T[2:0] bits in the serial data stream. See the programming section for more information.

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PROGRAMMING INTERFACE

ClockWorks™

SY89429A

Programming the device is accomplished by properly configuring the internal dividers to produce the desired frequency at the outputs. The output frequency can be represented by this formula:

M N

Where F

FOUT = ( ) x

XTAL is the crystal frequency, M is the loop divider

FXTAL

modulus, and N is the output divider modulus. Note that it is possible to select values of M such that the PLL is unable to achieve loop lock. To avoid this, always make sure that M is selected to be 200 ≤ M ≤ 400 for a 16MHz input reference.

M[8:0] and N[1:0] are normally specified once at power-on, through the parallel interface, and then possibly again through the serial interface. This approach allows the designer to bring up the application at one frequency and then change or finetune the clock, as the ability to control the serial interface becomes available. To minimize transients in the frequency domain, the output should be varied in the smallest step size possible.

T2 T1 T0 TEST FOUT / FOUT

0 0 0 Data Out – Last Bit SR FVCO ÷ N 0 0 1 HIGH FVCO ÷ N 0 1 0 FREF FVCO ÷ N 0 1 1 M Counter Output FVCO ÷ N 1 0 0 FOUT FVCO ÷ N 1 0 1 LOW FVCO ÷ N 110S_CLOCK ÷ MS_CLOCK ÷ N 1 1 1 FOUT ÷ 4 FVCO ÷ N

The TEST output provides visibility for one of several internal nodes (as determined by the T[1:0] bits in the serial configuration stream). It is not configurable through the parallel interface. Although it is possible to select the node that represents FOUT, the TTL output may not be able to toggle fast enough for some of the higher output frequencies. The T2, T1, T0 configuration latches are preset to 000 when P_LOAD is low, so that the FOUT outputs are as jitter-free as possible. The serial configuration port can be used to select one of the alternate functions for this pin.

The Test register is loaded with the first three bits, the N register with the next two and the M register with the final eight bits of the data stream on the S_DATA input. For each register the most significant bit is loaded first (T2, N1 and M8).

When T[2:0] is set to 100 the SY89429A is placed in PLL bypass mode. In this mode the S_CLOCK input is fed directly into the M and N dividers. The N divider drives the FOUT differential pair and the M counter drives the TEST output pin. In this mode the S_CLOCK input could be used for low speed board level functional test or debug. Bypassing the PLL and driving FOUT directly gives the user more control on the test clocks sent through the clock tree (See detailed Block Diagram). Because the S_CLOCK is a TTL level the input frequency is limited to 250MHz or less. This means the fastest the FOUT pin can be toggled via the S_CLOCK is 125MHz as the minimum divide ratio of the N counter is 2. Note that the M counter output on the TEST output will not be a 50% duty cycle due to the way the divider is implemented.

_CLOCK

_DATA

_LOAD

M[8:0] N[1:0]

_LOAD

T2 T1 T0 N1 N0 M8 M7 M6 M5 M4 M3 M2 M1 M0

First

Bit

M,N

Input S_DATA to M0 then M1, then M2, etc., as indicated above.

Last

Bit

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SY89429A

100H ECL DC ELECTRICAL CHARACTERISTICS

VCC1 = VCC_QUIET = VCC_TTL = +5.0V ±5%; VCC_OUT = +3.3V to +5.0V ±5%; TA = 0°C to +75°C

Symbol Parameter Min. Max. Unit Condition

VOH Output HIGH Voltage VCC_OUT –1.075 VCC_OUT –0.830 V 50Ω to VCC_OUT –2V V

OL Output LOW Voltage VCC_OUT –1.860 VCC_OUT –1.570 V 50Ω to VCC_OUT –2V

TTL DC ELECTRICAL CHARACTERISTICS

VCC1 = VCC_QUIET = VCC_TTL = +5.0V ±5%; VCC_OUT = +3.3V to +5.0V ±5%; TA = 0°C to +75°C

A = 0°CTA = +25°CTA = +75°C

Symbol Parameter Min. Max. Min. Max. Min. Max. Unit Condition

VIH Input HIGH Voltage 2.0 — 2.0 — 2.0 — V — VIL Input LOW Voltage — 0.8 — 0.8 — 0.8 V — IIH Input HIGH Current — 50 — 50 — 50 µAVIN = 2.7V IIL Input LOW Current —–0.6 —–0.6 —–0.6 mA VIN = 0.5V VIK Input Clamp Voltage —–1.2 —–1.2 —–1.2 V IIN = –12mA VOH Output HIGH Voltage — 2.5 — 2.5 — 2.5 V IOH = –2.0mA VOL Output LOW Voltage — 0.5 — 0.5 — 0.5 V IOL = 8mA IOS Output Short Circuit Current –80 (Typ.) –80 (Typ.) –80 (Typ.) mA VOUT = 0V I

CC1 Supply Current — 225 — 225 — 225 mA —

Typical % of I

CC1 VCC1 91% 91% 91%

VCC_OUT 4.5% 4.5% 4.5%

VCC_QUIET 2.25% 2.25% 2.25%

VCC_TTL 2.25% 2.25% 2.25%

AC ELECTRICAL CHARACTERISTICS

VCC1 = VCC_QUIET = VCC_TTL = +5.0V ±5%; VCC_OUT = +3.3V to +5.0V ±5%; TA = 0°C to +75°C

TA = 0°CTA = +25°CTA = +75°C

Symbol Parameter Min. Max. Min. Max. Min. Max. Unit Condition

fMAXI Maximum Input Frequency

MAXO Maximum Output Frequency VCO (Internal) 400 800 400 800 400 800 MHz

tLOCK Maximum PLL Lock Time — 10 — 10 — 10 ms tjitter Cycle-to-Cycle Jitter (Peak-toPeak) — ±25 — ±25 — ±25 ps Test output static tS Setup Time S_DATA to S_CLOCK 20 — 20 — 20 — ns

H Hold Time S_DATA to S_CLOCK 20 — 20 — 20 — ns

pw(MIN) Minimum Pulse Width S_LOAD 50 — 50 — 50 — ns

tDC FOUT Duty Cycle 45 55 45 55 45 55 % t

r Output Rise/Fall FOUT 300 800 300 800 300 800 ps

tf 20% to 80%

NOTE:

1. 10MHz is the maximum frequency to load the feedback divide registers. S_CLOCK can be switched at high frequencies when used as a test clock in TEST_MODE 6.

(1)

S_CLOCK — 10 — 10 — 10 MHz Fundamental

Xtal Oscillator 10 25 10 25 10 25 Cyrstal

FOUT 25 400 25 400 25 400

CLOCK to S_LOAD 20 — 20 — 20 —

M, N to P_LOAD 20 — 20 — 20 —

S_CLOCK to S_LOAD 20 — 20 — 20 —

M, N to P_LOAD 20 — 20 — 20 —

P_LOAD 50 — 50 — 50 —

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TIMING DIAGRAM

DATA

CLOCK

LOA

M[8:0]

N[1:0]

LOAD

SET-UP

HOLD

ClockWorks™

SY89429A

PRODUCT ORDERING CODE

SET-UP

Ordering Package Operating

Code Type Range

SY89429AJC J28-1 Commercial SY89429AJCTR J28-1 Commercial SY89429AZC Z28-1 Commercial SY89429AZCTR Z28-1 Commercial

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28 LEAD SOIC .300" WIDE (Z28-1)

ClockWorks™

SY89429A

Rev. 02

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28 LEAD PLCC (J28-1)

ClockWorks™

SY89429A

Rev. 03

MICREL-SYNERGY 3250 SCOTT BOULEVARD SANTA CLARA CA 95054 USA

TEL + 1 (408) 980-9191 FAX + 1 (408) 914-7878 WEB http://www.micrel.com

This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or

other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc.