ZSPM1025A
True Digital PWM Controller (Single-Phase, Single-Rail)
Figure 3.2
Power Sequencing
VOUTnom
0 V
t
tON_DELAY
tON_RISE
tOFF_DELAY
tOFF_FALL
OPERATION_ON
Control pin
OPERATION_OFF
Control pin
tON_MAX
tOFF_MAX
3.3.5.
Pre-biased Start-up and Soft Stop
Dedicated pre-biased start-up logic ensures proper start-up of the power converter when the output capacitors are
pre-charged to a non-zero output voltage. Closed-loop stability is ensured during this phase.
The ZSPM1025A also supports pre-biased off, i.e. the output voltage is not ramped down to zero and instead
remains at a predefined level (VOFF_nom). This value can be configured via the Pink Power Designer™. After
receiving the shutdown command via the PMBus™ or the CONTROL pin, the ZSPM1025A ramps down the
output voltage value to the predefined value. Once the value is reached, the PWM output will be put into tri-state
mode in order to put the output driver into its tri-state mode.
Figure 3.3
Power Sequencing with Non-zero Off Voltage
VONnom
Tri-state
VOFFnom
0 V
t
tON_DELAY
tON_RISE
tOFF_DELAY
tOFF_FALL
tON_MAX
tOFF_MAX
© 2013 Zentrum Mikroelektronik Dresden AG — Rev. 1.00
All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the
prior written consent of the copyright owner. The information furnished in this publication is subject to changes without notice.
Data Sheet
October 24, 2013
18 of 46
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