AMIS−52150

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7

CREF, Current Reference Bias Pin

A resistor must be connected to the CREF pin to provide

a current bias to the internal bandgap voltage reference

circuit. It is critical that this resistor value is 33.2 k

W (with

one percent or better tolerance) to achieve proper operation

of the bandgap voltage reference.

GND, Ground Pin

The GND pin is the ground connection for the digital and

analog circuits.

CLKOUT, Internal Clock Output Pin

The CLKOUT pin is an output for the RC oscillator,

crystal oscillator signal or the recovered data clock,

respectively. The crystal oscillator signal output can be

divided by 2, 3 or 4. The pin can also be programmed to

output the signal from the recovered data clock function. For

more information about the clock and data recovery (CDR)

function of the AMIS−52150, refer to the section of this

document on clock and data recovery.

The CLKOUT pin function control registers are shown in

Table 8.

Table 8. OSCILLATOR OUTPUT CONTROL REGISTERS

CLKOUT Pin Definition Control Registers

Register (HEX)

Name

Bits

States

Comments

0x0c

CLKOUT Enable

7

0

CLKOUT is Enabled

1

CLKOUT is Disabled

0x0d

CLKOUT Select

4, 5

00

Automatic Control

01

RC OSC

10

Xtal

11

Off

0x0e

XTAL Divide

0, 1

00

Divide by 4

01

Divide by 3

10

Divide by 2

11

Divide by 1

X1, X2, External Crystal Reference Pins

X1 and X2 pins connect a parallel resonance oscillator

crystal to the AMIS−52150 internal oscillator circuit. The

external crystal should meet the requirements as listed in

Table 9. However, the two load capacitors should be sized

slightly smaller than the recommended value for the crystal,

because of the added capacitance due to the internal trim

circuit. The crystal parameters are shown in Table 9.

Table 9. EXTERNAL CRYSTAL PARAMETERS

Parameter

Min

Typ

Max

Unit

Conditions

Crystal Frequency

12.56

−

12.65

MHz

Targeted

9.375

−

24.0

Non-quick Start

10.9

−

14.0

Quick Start

Crystal ESR

−

−

70

W

Crystal Tolerance

−

10

−

ppm

Load Capacitance

Load Capacitors should be Smaller than Recommended for the Crystal to allow for Frequency Tuning

device. The clock for the interface is generated by the

external master device. The interface will support the

normal (0 – 100 kbits/second) or the fast (0 –

400 kbits/second) data modes. The interface conforms to the

internal pull-up resistors. See Table 10 and Table 11 for

some parameters of this interface.

In addition, Table 12 shows the details of register that

Pin

Function

Typ

Unit

Internal Pull-up R

15

kW

Internal Pull-up R

15

kW