TYPICAL PERFORMANCE
GRAPHS
PA94
�ꢓꢆꢎꢂꢄꢃꢂꢎ�ꢀꢉꢎꢂ
�ꢀꢁꢂꢃꢄꢅꢂꢃꢆꢇꢈꢉꢊ
ꢒꢋꢈꢂꢎꢏꢂꢉꢇꢄꢏꢋꢃꢃꢂꢉꢇ
ꢢ�
ꢱꢭ�
ꢱꢃꢀ�
ꢱꢃꢁ�
ꢱꢃꢠ�
ꢃꢬ�ꢠ
ꢃꢬ�ꢟ
ꢃꢬ��
ꢀꢁ
ꢀ�
ꢃꢁ
ꢄꢌꢧꢌꢄꢏ
ꢏꢏꢌꢧꢌꢀꢀꢌꢵꢙ
ꢏꢏꢌꢧꢌꢟꢬꢂꢵꢙ
ꢬꢭꢡ
ꢬꢭꢀ
ꢬꢠꢠ
ꢄꢌꢧꢌꢄꢉ
ꢃ�
ꢱꢀꢃ�
ꢱꢀꢟ�
ꢁ
�
ꢏꢏꢌꢧꢌꢀꢬꢀꢵꢙ
�
ꢀꢁ ꢁ� ꢂꢁ ꢃ�� ꢃꢀꢁ ꢃꢁ�
ꢄꢅꢆꢇꢅꢈꢉꢄꢊꢈꢅꢋꢌꢄꢌꢍꢎꢏꢐ
ꢃꢆ
ꢃ�ꢆ ꢀ�ꢆ
ꢙꢈꢅꢚꢊꢅꢒꢏꢛꢋꢌꢙꢌꢍꢜꢝꢐ
�
ꢀ��
ꢟ�� ꢡ��
ꢠ�� ꢃ���
ꢄꢔꢄꢉꢓꢌꢗꢊꢇꢇꢓꢛꢌꢤꢔꢓꢄꢉꢥꢅꢋꢌꢤꢗꢌꢍꢤꢐ
ꢎꢐꢆꢍꢍꢄꢎꢈꢊꢉꢆꢍꢄꢃꢂꢎ�ꢀꢉꢎꢂ
ꢀꢋꢇ�ꢋꢇꢄꢌꢀꢍꢇꢆꢊꢂꢄꢎꢁꢈꢉꢊ
�ꢀꢁꢂꢃꢄꢃꢂꢎ�ꢀꢉꢎꢂ
ꢟ�
ꢃꢀ�
ꢃꢘ
ꢃ��
ꢠ�
ꢢꢀ
ꢀꢟ
ꢃꢡ
ꢠ
ꢁ��
ꢏꢏꢌꢧꢌꢀꢬꢀꢵꢙ
ꢏꢏꢌꢧꢌꢟꢬꢂꢵꢙ
ꢏꢏꢌꢧꢌꢀꢀꢌꢵꢙ
ꢡ�
ꢀ��
ꢟ�
ꢃ��
ꢁ�
ꢀ�
�
ꢟ
ꢃ��
ꢃ�ꢘ
ꢃ��ꢘ
ꢃꢆ ꢀꢆ
�
ꢀ�
ꢟ�
ꢡ�
ꢠ�
ꢃ� ꢃ�� ꢃꢘ ꢃ�ꢘꢃ��ꢘ ꢃꢆ ꢃ�ꢆꢀ�ꢆ
ꢔꢊꢄꢇꢊꢄꢌꢏꢊꢈꢈꢅꢒꢄꢋꢌꢑꢔꢌꢍꢞꢉꢐ
ꢙꢈꢅꢚꢊꢅꢒꢏꢛꢋꢌꢙꢌꢍꢜꢝꢐ
ꢙꢈꢅꢚꢊꢅꢒꢏꢛꢋꢌꢙꢌꢍꢜꢝꢐ
ꢏꢋꢃꢃꢂꢉꢇꢄꢍꢈꢐꢈꢇ
ꢎꢆꢑꢂꢄꢀ�ꢂꢃꢆꢇꢈꢉꢊꢄꢆꢃꢂꢆ
ꢈꢉ�ꢋꢇꢄꢉꢀꢈꢎꢂ
ꢀ�
ꢃꢁ
ꢀꢁ�
ꢀ��
ꢃꢁ�
ꢃ��
ꢃꢀ�
ꢃ��
ꢃ�
ꢂ�
ꢁ�
ꢁ�
ꢀꢁ
ꢂ
ꢁ
ꢢ�
ꢀ�
ꢃꢁ
ꢃ�
ꢢ
ꢀ
ꢇꢊꢓꢗꢅꢌꢏꢊꢈꢤꢅꢗꢌꢩ
ꢃ�ꢪꢌꢖꢊꢄꢛꢌꢏꢛꢏꢓꢅꢌꢆꢉꢫ
ꢁ
ꢃ�
ꢁ�
ꢃ��
ꢀ��
ꢁ��
ꢃꢘ
ꢢ
ꢁ
ꢃ�
ꢀ�
ꢁ� ꢃ��ꢃꢁ�
ꢃ�
ꢃ��
ꢃꢘ
ꢃ�ꢘ
ꢃꢆ
ꢏꢊꢈꢈꢅꢒꢄꢌꢓꢑꢆꢑꢄꢌꢈꢅꢗꢑꢗꢄꢔꢈꢋꢌꢈꢏꢓꢌꢍꢣꢐ
ꢙꢈꢅꢚꢊꢅꢒꢏꢛꢋꢌꢙꢌꢍꢜꢝꢐ
ꢗꢊꢇꢇꢓꢛꢌꢄꢔꢌꢔꢊꢄꢇꢊꢄꢌꢖꢑꢙꢙꢅꢈꢅꢒꢄꢑꢉꢓꢋꢌꢤꢗꢌꢦꢤꢔꢌꢍꢤꢐ
Tc - Ta
INTERNAL POWER DISSIPATION AND HEATSINK SELECTION
RØSA
=
-0.1°C/W
PD + PDQ
With the unique combination of high voltage and speed
of the PA94, traditional formulas for heatsink selection will
falsely lower the apparent power handling capability of this
amplifier. To more accurately predict operating temperatures
use Power Design1 revision 10 or higher, or use the following
procedure:
Find internal dissipation (PD) resulting from driving the
load. Use Power Design or refer to Apex Applications Note
1, General Operating Considertaions, paragraph 7. Find total
quiescent power (PDQ) by multiplying 0.024A by VSS (total
Where: TC = maximum case temperature allowed
TA = maximum ambient temperature encountered
Calculateaheatsinkratingwhichwillmaintainoutputtransistor
junctions at 150°C or lower.
TJ - Ta - (PD + PDQOUT) *RØJC
RØSA
=
-0.1°C/W
PD + PDQ
Where: TJ = maximum junction temperature allowed.
RØJC = AC or DC thermal resistance from the specification
table.
supply voltage). Find output stage quiescent power (PDQOUT
)
Use the larger heatsink of these two calculations.
by multiplying 0.00012 by VSS.
Calculate a heatsink rating which will maintain the case at
85°C or lower.
Power Design is an Excel spreadsheet available free from
www.apexmicrotech.com
APEX MICROTECHNOLOGY CORPORATION • TELEPHONE (520) 690-8600 • FAX (520) 888-3329 • ORDERS (520) 690-8601 • EMAIL prodlit@apexmicrotech.com
3