SMH4046 Datasheet, PDF (15/51 Pages) List of Unclassifed Manufacturers – Hot-Swap, Active DC Output Control (ADOCTM) Power Manager with I2C lnterface

APPLICATIONS INFORMATION (CONTINUED)
SMH4046
Preliminary Information
Using the schematic in Figure 6 and assuming all input
voltages are within the programmed limits, application
of power to the SMH4046 will enable all DC-DC
converters according to the sequence programmed for
each channel in the SMH4046. An I²C software
Power-On command can also be used to enable the
DC-DC converters. The waveforms in Figure 7 were
generated using Channel 1 (12V output) for the time-
base trigger. Note the outputs are asserted once the
pre-programmed time limit is passed.
Conversely, the SMH4046 can issue an I²C Power-Off
command (Figure 8). The SMH4046 reverses the
Power-Off sequence; that is, the first supply to shut off
is the last to have turned on (Channel 4 in this case).
As displayed in Figure 8, the supplies are turned off in
reverse order of the turn-on sequence.
Figure 8: SMH4046EV Sequence-Off Waveforms
Tektronix TDS3054: Time/Horizontal division =
100mS
Ch 1(2V/Div) = 12V output (Yellow trace)
Ch 2 (1V/Div) = 1.8V DC-DC converter output (Blue trace)
Ch 3 (1V/Div) = 2.5V DC-DC converter output (Purple trace)
Ch 4 (1V/Div) = 5.0V output (Green trace)
The SMH4046’s has many features including the
ability to change the channel sequence positions and
slew-rates for system flexibility and software
programmability to simplify changes. Figure 9 displays
the SMH4046 margining the 2.5V converter high and
the 1.8V converter low.
Figure 7: SMH4046EV Sequence-On Waveforms
Tektronix TDS3054: Time/Horizontal division = 40mS
Ch 1(2V/Div) = 12V output (Yellow trace)
Ch 2 (1V/Div) = 1.8V DC-DC converter output (Blue trace)
Ch 3 (1V/Div) = 2.5V DC-DC converter output (Purple trace)
Ch 4 (1V/Div) = 5.0V output (Green trace)
Summit Microelectronics, Inc
2082 1.7 08/23/04
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