DSP56156ROM datasheet(20/76 Pages) MOTOROLA

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AC Electrical Characteristics and Timing

DSP56156 Data Sheet

MOTOROLA

AC Electrical Characteristics

(GND = 0 V dc)

The timing waveforms in the AC Electrical Characteristics are tested with a VIL maximum of

0.5 V and a VIH minimum of 2.4 V for all pins, except EXTAL, RESET, MODA, MODB and

MODC. These five pins are tested using the input levels set forth in the DC Electrical Charac-

teristics

. AC timing specifications which are referenced to a device input signal are measured

in production with respect to the 50% point of the respective input signal’s transition. The

DSP56156 output levels are measured with the production test machine VOL and VOH refer-

ence levels set at 0.8 V and 2.0 V respectively.

Clock Operation Timing

The system clock to the DSP56156 must be externally supplied to EXTAL as illustrated in

Figure 6.

NOTES: 1. Rise and fall time may be relaxed to 12 ns maximum if the EXTAL input frequency is less than or equal

to 20 MHz. If the EXTAL input frequency is between 20 MHz and 40 MHz, rise and fall time should

meet the specified values in the 40 MHz column (4 ns maximum).

2. The duty cycle may be relaxed to 43-57% if the EXTAL input frequency is less than or equal to 20 MHz.

If the EXTAL input frequency is between 20 MHz and 40 MHz, the duty cycle should be such that TH

and TL meet the specified values in the 40 MHz column (12 ns minimum).

3. T = ICYC / 4 is used in the electrical characteristics. The exact length of each T is affected by the duty

cycle of the external clock input.

4. Duty cycles and EXTAL widths are measured at the EXTAL input signal midpoint when AC coupled and

at VCC/2 when not AC coupled.

Table 11 Clock Operation Timing

Num

Characteristics

Sym

40 MHz

50 MHz

60 MHz

Unit

Min

Max

Min

Max

Min

Max

Frequency of Operation (EXTAL)

MHz

Instruction Cycle Time = 2TC

ICYC

×40×33

Wait State Time = TC = 2T

—

16.6

EXTAL Cycle Period

16.6

EXTAL Rise Time (See Note 1)

—

EXTAL Fall Time (See Note 1)

—

EXTAL Width High

48-52% duty cycle

(See Notes 2, 3, 4)

9.6

EXTAL Width Low

48%-52% duty cycle

(See Notes 2, 3, 4)

9.6

Clock Operation Timing

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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