CS5166GDWR16 View Datasheet(PDF) - ON Semiconductor
Part Name
Description
MFG CO.
'CS5166GDWR16' PDF : 25 Pages View PDF
CS5166
Soft Start capacitor is charged to its upper 2.7 V threshold.
During an overload condition the Soft Start
charge/discharge current ratio sets the duty cycle for the
pulses (2.0 μA/60 μA = 3.3%), while actual duty cycle is half
that due to the extended off time mode (1.65%) when VFB
is less than 1.0 V. The Soft Start hiccup pulses last for a 3.0
ms period at the end of which the duty cycle repeats if a fault
is detected, otherwise normal operation resumes.
The protection scheme minimizes thermal stress to the
regulator components, input power supply, and PC board
traces, as the overcurrent condition persists. Upon removal
of the overload, the fault latch is cleared, allowing normal
operation to resume. The current limit trip point can be
adjusted through an external resistor, providing the user with
the current limit set−point flexibility.
MOSFET to shut off, disconnecting the regulator from it’s
input voltage. The bottom MOSFET is then activated,
resulting in a “crowbar” action to clamp the output voltage
and prevent damage to the load (see Figures 21 and 22 ). The
regulator will remain in this state until the overvoltage
condition ceases or the input voltage is pulled low. The
bottom FET and board trace must be properly designed to
implement the OVP function. If a dedicated OVP output is
required, it can be implemented using the circuit in Figure
23. In this figure the OVP signal will go high (overvoltage
condition), if the output voltage (VCORE) exceeds 20% of
the voltage set by the particular DAC code and provided that
PWRGD is low. It is also required that the overvoltage
condition be present for at least the PWRGD delay time for
the OVP signal to be activated. The resistor values shown in
Figure 23 are for VDAC = +2.8 V (DAC = 10111). The VOVP
(overvoltage trip−point) can be set using the following
equation:
ǒ Ǔ VOVP
+ VBEQ3
1
)
R2
R1
M 25.0 ms
Trace 4− 5.0 V Supply Voltage (2.0 V/div.)
Trace 3− Soft Start Timing Capacitor (1.0 V/div.)
Trace 2− Inductor Switching Node (2.0 V/div.)
Figure 19. Demonstration Board Hiccup Mode Short
Circuit Protection. Gate Pulses are Delivered While
the Soft Start Capacitor Charges, and Cease During
Discharge
M 10.0 μs
Trace 4− 5.0 V from PC Power Supply (5.0 V/div.)
Trace 1− Regulator Output Voltage (1.0 V/div.)
Trace 2− Inductor Switching Node 5.0 V/div.)
Figure 21. OVP Response to an Input−to−Output
Short Circuit by Immediately Providing 0% Duty
Cycle, Crow−Barring the Input Voltage to Ground
M 50.0 μs
Trace 4− 5.0 V from PC Power Supply (2.0 V/div.)
Trace 2− Inductor Switching Node (2.0 V/div.)
Figure 20. Demonstration Board Startup with
Regulator Output Shorted To Ground
Overvoltage Protection
Overvoltage protection (OVP) is provided as result of the
normal operation of the V2 control topology and requires no
additional external components. The control loop responds
to an overvoltage condition within 100 ns, causing the top
M 5.00 ms
Trace 4− 5.0 V from PC Power Supply (2.0 V/div.)
Trace 1− Regulator Output Voltage (1.0 V/div.)
Figure 22. OVP Response to an Input−to−Output Short
Circuit by Pulling the Input Voltage to Ground
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