Analog Devices ee-46 Application Notes

Engineer To Engineer Note EE-46

Notes on using Analog Devices’ DSP, audio, & video components from the Computer Products Division

Phone: (800) ANALOG-D or [phone], FAX: [phone], EMAIL: [e-mail]

SHARC Internal Power
Consumption Measurements

Last Modified: 6/6/96

There have been many customer inquiries concerning
typical power consumption of the SHARC processors.
As you all know we only supply a maximum Pint which
is based on experimentation. Iddin is measured while
executing a radix-2 FFT butterfly with instruction in
cache, one data fetch from each block of memory and a
DMA transfer from internal memory to internal memory.
A similar method of experimentation to try to determine
"typical power".

The first issue was to determine what "typical"
instructions would be so "typical" power can be
determined. A guess was taken. The following is a
description of the test cases:

Test Case 1 executes an addition, a subtraction, a PM
data access and a DM data access.

Test Case 2 executes a multiplication, an addition, a PM
data access and a DM data access.

Test case 3 executes a multiplication, an addition, a
subtraction, a PM data access and a DM data access.

Test Case 4 executes a multiplication, an addition and a
subtraction.

Test Case 5 executes an addition and a subtraction.
Test Case 6 executes a PM data access and a DM data

access.

Test cases were selected assuming "typical" instructions
would be associated with number crunching. A jump
statement was used to sustain these instructions.

The experiments where performed on an ADSP 21062 rev

2.0 using 3 separate clock rates, 25MHz, 33 MHz, and 40
MHz. (A rev 0.6 part with a 24 MHz clock was also
tested. The results were almost identical to those of the
rev 2.0). Vddin was fixed at 5.25v. The following table
describes the results:

Test CaseIddin @ 24 MHz Iddin @ 33 MHz Iddin @ 40
MHz
1 380 mA 410 mA 470 mA
2 400 mA 440 mA 500 mA
3 400 mA 440 mA 510 mA
4 280 mA 330 mA 370 mA
5 280 mA 320 mA 360 mA
6a 320 mA 380 mA 420 mA
(50% Switching)
6b 390 mA 440 mA
(100% Switching)

The following is a copy of the program used.
#include "def21060.h"

#define N 22

.SEGMENT/DM seg_dmda;
.VAR buffdm[4] =0x00000000,

0x55555555,
0xFFFFFFFF,
0xAAAAAAAA;

.ENDSEG;

.SEGMENT/PM seg_pmda;
.VAR buffpm[N] =0x4AA14B47,

0x8DF675D4,
0x43D49B8A,
0xD14BA018,
0x406E4387,
0xCDE5483D,
0x83C36DCA,
0x113A7239,
0x805D15C7,
0x363B3B7C,
0xC3B24032,
0x799065C0,
0x07076A2F,
0x762A0DBC,
0x03A1122C,
0x72C3B5B9,
0x28A1DB6F,
0xB618E025,
0x6BF705B2,
0xF96E0A21,
0x6890ADAF,
0x1E6ED365;

.ENDSEG;
.SEGMENT/PM seg_rth;

nop;

jump start;

a

.ENDSEG;
.SEGMENT/PM seg_pmco;
start:

l0=@buffdm;
b0= buffdm;
m0= 0x1;

l8=@buffpm;
b8= buffpm;
m8= 0x1;

r0=dm(i0,m0), r4 =pm(i8,m8);
r8=dm(i0,m0), r12=pm(i8,m8);

call addsub;
addsub:

r7=r0+r4, r15=r0-r4, r0=dm(i0,m0), r4 =pm(i8,m8);
jump addsub (db);
r7=r0+r4, r15=r0-r4, r0=dm(i0,m0), r4 =pm(i8,m8);
r7=r0+r4, r15=r0-r4, r0=dm(i0,m0), r4 =pm(i8,m8);

mulacc:
r7=r0*r4(SSFR), r15=r8+r12, r0=dm(i0,m0), r4
=pm(i8,m8);
jump mulacc (db);
r7=r0*r4(SSFR), r15=r8+r12, r0=dm(i0,m0), r4
=pm(i8,m8);
r7=r0*r4(SSFR), r15=r8+r12, r0=dm(i0,m0), r4
=pm(i8,m8);

mas: r7=r0*r4(SSFR), r15=r8+r12, r14=r8-r12,
r0=dm(i0,m0), r4 =pm(i8,m8);
jump mas (db);
r7=r0*r4(SSFR), r15=r8+r12, r14=r8-r12,
r0=dm(i0,m0), r4 =pm(i8,m8);
r7=r0*r4(SSFR), r15=r8+r12, r14=r8-r12,
r0=dm(i0,m0), r4 =pm(i8,m8);

.ENDSEG;

EE-46 Page 2

Notes on using Analog Devices’ DSP, audio, & video components from the Computer Products Division

Phone: (800) ANALOG-D or [phone], FAX: [phone], EMAIL: [e-mail]