SM8721AB

SEIKO NPC CORPORATION —2

BLOCK DIAGRAM

PIN DESCRIPTION

Number

Name

I/O

Description

1

VDD3

–

Analog supply voltage 3

2

VDD3

–

Analog supply voltage 3

3

VSS3

–

Analog supply ground 3

4

XTI

I

Crystal oscillator element connection pin (14.318182/28.636363MHz)

5

XTO

O

Crystal oscillator element connection pin

6

TEST1

I

Test pin 1. Built-in pull-down resistance (leave open circuit or connect to VSS)

7

XTAL_SEL

I

Crystal oscillator element selection pin. Built-in pull-up resistance

(HIGH = 28.636MHz, LOW = 14.318MHz)

8

FS3

I

CLK1, CLK2 output select 3. Built-in pull-up resistance

9

FS2

I

CLK1, CLK2 output select 2. Built-in pull-up resistance

10

FS1

I

REF_CLK output select 1. Built-in pull-up resistance

11

CLK1

O

Clock output (71/90/96/114MHz switchable output)

12

CLK2ON

I

CLK2 output enable. Built-in pull-up resistance (HIGH = enable, LOW = disable)

13

VSS1

–

Digital supply ground 1

14

VDD1

–

Digital supply voltage 1

15

VDD1

–

Digital supply voltage 1

16

CLK2

O

Clock output (48/96MHz switchable output)

17

VSS2

–

Digital supply ground 2

18

VDD2

–

Digital supply voltage 2

19

REF_CLK

O

Clock output (14.318/17.734MHz switchable output)

20

TEST2

I

Test pin 2. Built-in pull-down resistance (leave open circuit or connect to VSS)

CLK2ON

Reference

Divider 1

Phase

Detector 1

Charge

Pump 1

LPF 1

VCO 1

Control

Logic

CLK1

Loop

Divider 1

(PLL1)

Reference

Divider 2

Phase

Detector 2

Charge

Pump 2

LPF 2

VCO 2

Loop

Divider 2

(PLL2)

Reference

Divider 3

Phase

Detector 3

Charge

Pump 3

LPF 3

VCO 3

Loop

Divider 3

(PLL3)

XTAL_SEL

CLK2

REF_CLK

FS2

FS1

Oscillator

XTO

XTI

FS3

TEST1

TEST2