SM645 Datasheet, PDF (3/4 Pages) Microsemi Corporation – SWITCHING REGULATOR POWER OUTPUT STAGES

ELECTRICAL CHARACTERISTICS (continued)
Parameter
Test Conditions
Dynamic Characteristics (See Figures 1 & 2) (Notes 4 & 5)
Current Delay Time
Current Rise Time
Voltage Rise Time
Voltage Storage Time
Voltage Fall Time
Current Fall Time
Efficiency (Note 5)
AC TEST CIRCUIT AND SWITCHING TIME WAVEFORMS (Note 6)
SM645
SM646
SM647
SM645/SM646/SM647
SG645/646/647 _Units
Min. Typ. Max.
35 60 _ns
65 150 _ns
40 60 _ns
700
ns
70 175 _ns
175 300 _ns
85
%
FIGURE 1 - SM645/646/647 SWITCHING SPEED CIRCUIT
FIGURE 2 - SM645/646/647 SWITCHING WAVEFORMS
Note 4. In switching an inductive load, the current will lead the voltage on turn-on and lag the voltage on turn-off (see Figure 2). Therefore, Voltage
Delay Time (t_DV) ≅ t_di + t_ri and Current Storage Time (t_si) ≅ t_sv + t_fv .
Note 5. The efficiency is a measure of internal power losses and is equal to Output Power divided by Input Power. The switching speed circuit of Figure
1, in which the efficiency measured, is represenative of typical operating conditions for the SM600 series switching regulators.
APPLICATION CIRCUITS
SM64X
SM64X
FIGURE 3 - STEP DOWN (BUCK) CONVERTER
4/90 Rev 1.1 2/94
Copyright © 1994
FIGURE 4 - NEGATIVE OUTPUT DOWN/UP (BUCK-BOOST) CONVERTER
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