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TDK-Lambda
DBM20
INSTRUCTION MANUAL
PA640-04-01B
4-10. The Buffer Current versus Buffer Time for
Fixed Mode and Nominal buffer Voltage.
Buffering time 0 – 2 seconds
NOTE : Ta=25⁰C and initial capacitance
Kindly refer to product specifications for more details
regarding hold up time.
4-11. Buffer Ripple and Noise
The standard specification for maximum ripple value is
measured according to measurement circuit shows in
figure 7. When load lines are longer, ripple becomes
larger. In this case, electrolytic capacitor,
film capacitor,
etc might be necessary across the load terminal.
4-12. The Timing Sequence Chart
Figure 7
(1)
The buffer module is connected to the upstream power supply. After AC input to the power supply, the output
from the power supply which is connected to the input/output of the buffer module will charge up the internal
circuit of the buffer module.
(2)
Once the input/output voltage reaches the threshold voltage of DC OK circuit, the DC OK signal will change
from logic high to logic low.
(3)
After approximately 40s, the bulk electrolytic capacitors voltage will be charged up to 220Vdc typical and the
Ready signal change from logic low to logic high.
(4)
If the AC input shutdown or brown out conditions, the output voltage from the upstream power supply will go
down. In this case, the input/output voltage of the buffer module will go down as well. The buffer module
senses this change and it will activate buffer mode. Please refer to section 4-2. for the nominal buffer voltage
level that the buffer module to supply back to the output line of the upstream power supply.
