VPOL16A-12W-SIP Datasheet, PDF (6/14 Pages) CUI INC – point of load converter

PART NUMBER: VPOL16A-12W-SIP
rev.
page 6 of 14
date 08/2007
DESCRIPTION: point of load converter
5.7 UVLO (Under-Voltage Lockout)
The voltage on the Vcc pin determines the start of the operation of the
Converter. When the input Vcc rises and exceeds about 5.0V the
converter initiates a soft start. The UVLO function in the converter has a
hysteresis (about 1V) built in to provide noise immunity at start-up.
5.8 Output Voltage Sequencing (Tracking)
The VPOL16A-12W-SIP series including a sequencing feature. It is able
implement various types of output voltage sequencing in customer
applications, VPOL16A-12W-SIP series is accomplishable through an
additional sequencing pin. When not using the sequencing feature, tie
the SEQ pin to +Vin. When the signal voltage is applied to the SEQ pin,
the output voltage tracks this voltage until the output reaches the set
point voltage. The SEQ voltage needs to be set higher than the set point
of the module. The output voltage will be follow by the voltage on the
SEQ pin. On the multiple modules application, we can connect SEQ pin
and input signal voltage together to apply on the SEQ pin. Customers
can get multiple modules to track their output voltages to follow the
voltage of the SEQ pin.
To control this module for sequen cing, when the input voltage
applied to the module. The on/off pin is left unconnected so that
the module is ON by default. After applying input voltage to the module, a
minimum of 10msec delay is required before applying voltage on the
SEQ pin and slew rate of the voltage on the SEQ pin see technical
specifications “ dVSEQ/dt “. After 10msec delay, an Analog voltage is
applied to the SEQ pin and the output voltage of the module will track
this voltage until output voltage reaches the set point voltage. To initiate
simultaneous shutdown of the modules, the SEQ pin voltage is lowered
in a controlled manner. Output voltage of the modules track the voltages
below their set-point voltage voltages. A valid input voltage must be
maintained until the tracking and output voltages reach ground potential
to ensure a controlled shutdown of the modules.
A typical example testing circuit used master DC/DC converter and
VPOL16A-12W-SIP Module as shown as below:
Power ₊
Supply
C1 CH1
+Vin
+Vo
Master DC/DC Converter
Common
Common
R1
Load
+Vin
+Vo
SEQ
CH2 ^{VPOL16A-12W-SIP}
R2
C2
CH3
Load
Common
Common
Figure 5. Example testing circuit of sequencing function
Power start up with SEQ signal
Input Voltage=12Vdc
Master DC/DC output voltage (CH1) = 5Vdc
Salve DC/DC output voltage (CH2)=3.3Vdc
Sequencing voltage= 0.6V/msec
Figure 6. Example testing circuit of sequencing function
Power turn off with SEQ signal voltage
Input Voltage=12Vdc (CH1)
Master DC/DC output voltage (CH2) = 5Vdc
Salve DC/DC output voltage (CH3)=3.3Vdc
Figure 7. Example testing circuit of sequencing function
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