MB39C308 Datasheet, PDF (21/60 Pages) Fujitsu Component Limited. – 6ch DC/DC Converter IC for LPIA Platform VR

MB39C308
■ DESCRIPTION OF SOFT-START AND SOFT-STOP OPERATION
Soft-start function is featured to avoid inrush current when each channels is turned-on. When the CTL1, CTL2,
CTL34, CTL5 and CTL6 are set to “H” level, ramped-up voltage is fed on an inverting input of an error amplifier
of a channel. Start-time of the soft-start can be predefined and the start time is kept constant independent from
a load of the output of the channels. When the CTL1, CTL2, CTL34, CTL5 and CTL6 are set to “L” level, ramped-
down voltage is fed on an inverting input of an error amplifier of a channel then the output voltage goes low.
Stop-time of the Soft-stop can be predefined and the stop-time is kept constant independent from a load of the
output of the channel.
The time of both soft-start and soft-stop can be predefined with combination of the level on the SS1 and the
SS2 pins as shown in the “• Soft-Start/Soft-Stop time (tson/tsoff) Setting Conditions”, and external capacitors
and resistors aren't required
• Soft-Start/Soft-Stop time (tson/tsoff) Setting Conditions
SS1 pin
SS2 pin
Soft-Start time Soft-Stop time
(tson) (Typ) * (tsoff) (Typ) *
Unit
Connecting to AGND pin
Connecting to AGND pin
1.4
1.4
ms
Connecting to AGND pin
Connecting to VREF pin
2.2
2.2
ms
Connecting to AGND pin
Connecting to VB pin
2.9
2.9
ms
Connecting to VREF pin
Connecting to AGND pin
3.5
3.5
ms
Connecting to VREF pin
Connecting to VREF pin
4.1
4.1
ms
Connecting to VREF pin
Connecting to VB pin
5.1
5.1
ms
Connecting to VB pin
Connecting to AGND pin
5.9
5.9
ms
Connecting to VB pin
Connecting to VREF pin
7.3
7.3
ms
Connecting to VB pin
Connecting to VB pin
8.2
8.2
ms
* : Accuracy : Typ ±15%
DS04-27261-6E
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