PXA270 datasheet(59/126 Pages) INTEL

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Electrical, Mechanical, and Thermal Specification

5-9

Intel® PXA270 Processor

Electrical Specifications

5.5

Oscillator Electrical Specifications

The PXA270 processor contains two oscillators: a 32.768-kHz oscillator and a 13.000-MHz

oscillator. Each oscillator requires a specific crystal.

5.5.1

32.768-kHz Oscillator Specifications

The 32.768-kHz oscillator is connected between the TXTAL_IN (amplifier input) and

TXTAL_OUT (amplified output). Table 5-9 and Table 5-10 list the appropriate 32.768-kHz

specifications.

To drive the 32.768-kHz crystal pins from an external source:

1. Drive the TXTAL_IN pin with a digital signal that has low and high levels as listed in

Table 5-10. Do not exceed VCC_PLL or go below VSS_PLL by more than 100 mV. The

minimum slew rate is 1 volt per 1 µs. The maximum current drawn from the external clock

source when the clock is at its maximum positive voltage is typically 1 mA.

2. Float the TXTAL_OUT pin or drive it in complement to the TXTAL_IN pin, with the same

voltage level and slew rate.

Caution: The TXTAL_IN and TXTAL_OUT pins must not be driven from an external source if the PXA270

processor sleep / deep sleep DC-DC converter is enabled.

VOH1

Output high voltage, all standard output and I/

O pins, relative to applicable VCC (VCC_IO,

VCC_MEM, VCC_BB, VCC_LCD, VCC_USB,

or VCC_USIM)

VCC - 0.3

VCC

IOH = -4 mA2,

-3 mA3

VOL1

Output low voltage, all standard output and I/O

pins, relative to applicable VSS (VSS_IO,

VSS_MEM, or VSS_BB)

VSS

VSS + 0.3

IOH = 4 mA2,

3 mA3

NOTES:

1. Programmable drive strengths set to 0x5 for memory and LCD programmable signals.

2. The current for the high-strength pins are MA<25:0>, MD<31:0>, nOE, nWE, nSDRAS, nSDCAS, DQM<3:0>, nSDCS<3:0>,

SDCKE<1>, SDCLK<3:0>, RDnWR, nCS<5:0>, and nPWE.

3. The current for all other output and I/O pins are low strength.

Table 5-8. Standard Input, Output, and I/O Pin DC Operating Conditions (Sheet 2 of 2)

Symbol

Description

Min

Max

Unit

Testing Conditions

/ Notes

Table 5-9. Typical 32.768-kHz Crystal Requirements (Sheet 1 of 2)

Parameter

Minimum

Typical

Maximum

Units

Frequency range

—

32.768

—

kHz

Frequency tolerance

–30

—

+30

ppm

Frequency stability, parabolic coefficient

—

–0.04

ppm/

(

∆°C)2

Drive level

—

1.0

Load capacitance (CL)

—

12.5

—

Shunt capacitance (CO)—

0.9

—

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