MSP430F5259 datasheet(55/107 Pages) TI1

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MSP430F5259, MSP430F5258, MSP430F5257, MSP430F5256

MSP430F5255, MSP430F5254, MSP430F5253, MSP430F5252

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SLAS903A – MAY 2013 – REVISED JULY 2013

Crystal Oscillator, XT1, Low-Frequency Mode

(1)

over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted)

PARAMETER

TEST CONDITIONS

VCC

MIN

TYP

MAX

UNIT

fOSC = 32768 Hz, XTS = 0,

XT1BYPASS = 0, XT1DRIVEx = 1,

0.075

TA = 25°C

fOSC = 32768 Hz, XTS = 0,

Differential XT1 oscillator crystal

ΔIDVCC.LF

current consumption from lowest

XT1BYPASS = 0, XT1DRIVEx = 2,

3.0 V

0.170

µA

drive setting, LF mode

TA = 25°C

fOSC = 32768 Hz, XTS = 0,

XT1BYPASS = 0, XT1DRIVEx = 3,

0.290

TA = 25°C

XT1 oscillator crystal frequency,

fXT1,LF0

XTS = 0, XT1BYPASS = 0

32768

LF mode

XTS = 0, XT1BYPASS = 1(2) (3)

XT1 oscillator logic-level square-

fXT1,LF,SW

32.768

kHz

wave input frequency, LF mode

XT1BYPASSLV = 0 or 1

XTS = 0,

XT1BYPASS = 0, XT1DRIVEx = 0,

210

fXT1,LF = 32768 Hz, CL,eff = 6 pF

Oscillation allowance for

OALF

Ω

LF crystals(4)

XTS = 0,

XT1BYPASS = 0, XT1DRIVEx = 1,

300

fXT1,LF = 32768 Hz, CL,eff = 12 pF

XTS = 0, XCAPx = 0(6)

XTS = 0, XCAPx = 1

5.5

Integrated effective load

CL,eff

capacitance, LF mode(5)

XTS = 0, XCAPx = 2

8.5

XTS = 0, XCAPx = 3

12.0

XTS = 0, Measured at ACLK,

Duty cycle, LF mode

fXT1,LF = 32768 Hz

XTS = 0,

Oscillator fault frequency,

fFault,LF

XT1BYPASS = 1(8),

10000

LF mode(7)

XT1BYPASSLV = 0 or 1

(1)

To improve EMI on the XT1 oscillator, the following guidelines should be observed.

(a) Keep the trace between the device and the crystal as short as possible.

(b) Design a good ground plane around the oscillator pins.

(d) Avoid running PCB traces underneath or adjacent to the XIN and XOUT pins.

(e) Use assembly materials and techniques that avoid any parasitic load on the oscillator XIN and XOUT pins.

(f) If conformal coating is used, make sure that it does not induce capacitive or resistive leakage between the oscillator pins.

(2)

When XT1BYPASS is set, XT1 circuits are automatically powered down. Input signal is a digital square wave with parametrics defined in

the Schmitt-Trigger Inputs section of this datasheet. When in crystal bypass mode, XIN can be configured so that it can support an input

digital waveform with swing levels from DVSS to DVCC (XT1BYPASSLV = 0) or DVSS to DVIO (XT1BYPASSLV = 1). In this case, it is

required that the pin be configured properly for the intended input swing.

(3)

Maximum frequency of operation of the entire device cannot be exceeded.

(4)

Oscillation allowance is based on a safety factor of 5 for recommended crystals. The oscillation allowance is a function of the

XT1DRIVEx settings and the effective load. In general, comparable oscillator allowance can be achieved based on the following

guidelines, but each application should be evaluated based on the actual crystal selected:

(a) For XT1DRIVEx = 0, CL,eff ≤ 6 pF

(b) For XT1DRIVEx = 1, 6 pF

≤ CL,eff ≤ 9 pF

≤ CL,eff ≤ 10 pF

(d) For XT1DRIVEx = 3, CL,eff ≥ 6 pF

(5)

Includes parasitic bond and package capacitance (approximately 2 pF per pin).

Because the PCB adds additional capacitance, it is recommended to verify the correct load by measuring the ACLK frequency. For a

correct setup, the effective load capacitance should always match the specification of the used crystal.

(6)

Requires external capacitors at both terminals. Values are specified by crystal manufacturers.

(7)

Frequencies below the MIN specification set the fault flag. Frequencies above the MAX specification do not set the fault flag.

Frequencies in between might set the flag.

(8)

Measured with logic-level input frequency but also applies to operation with crystals.

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