NCP5212A_09 ONSEMI [ON Semiconductor], NCP5212A_09 Datasheet - Page 14

• Manufacturer Part Number: NCP5212A_09
• Description: Single Synchronous Step-Down Controller
• Manufacturer: ONSEMI [ON Semiconductor]

The load line impendence R
Where DCR is inductor DC resistance. Gain_CS is a gain
from [(CS+)−(CS−)] to IDRP Gain (At electrical table, the
symbol is IDRP_GAIN), the typical value is 0.525 mA/mV.
Rocp resistor into ground.
resistor Rt can affect the amount of R
recommended to define the amount of R
defining the compensation component value. And if the user
wants to fine tune the compensation network for optimizing
the transient performance, it is NOT recommend to adjust
the value of Rt. Otherwise, both transient performance and
AVP amount will be affected. The following diagram shows
the typical waveform of AVP. Note that the Rt typical value
should be above 1 kW.
Over Current Protection (OCP)
over current event occurs. The current is continuously
monitored by the differential current sensing circuit. The
current limit threshold voltage VOCSET can be
programmed by resistor ROCSET connecting at the
IDRP/OCP pin. However, fixed default VOCSET can be
achieved if ROCSET is less than 2 kW.
continuously, the top gate driver will be turned off cycle by
cycle. If it happens over consecutive 16 clock cycles time
(16 x 1/f
bottom gate drivers are off. EN resets or power recycle the
device can exit the fault. The following diagram shows the
typical behavior of OCP.
The AVP function can be easily disable by shorting the
From the equation we can see that the value of “top”
The NCP5212A/NCP5212T protects power system if
If the inductor current exceeds the current threshold
R
SW
Figure 22. Typical waveform of AVP
LL
Top to Bottom: SWN, Vo, Transient Signal
), the device is latched off such that top and
+ DCR * Gain_CS * Rt *
LL
is given by:
Rs1 ) Rs2
LL
Rs2
FRIST before
LL
, so it is
(eq. 3)
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14
current sensing for acquiring current information. In
addition, the threshold OCP voltage can be programmed to
some desired value by setting the programming resistor
Rocp.
Rocp resistor. If Adaptor Voltage Position (AVP) is used, the
Rocp should be connected to FB pin. If AVP is not used, the
Rocp should be connected to ground. At the IDRP/OCP pin,
there is a constant current(24 mA typ.) flowing out during the
The NCP5212A/NCP5212T uses lossless inductor
It should be noted that there are two configurations for
DCR
DCR
Vo
L
Figure 23. Overcurrent Protection
Vo
L
Top to Bottom : SWN, Vo, PGOOD, Io
Figure 24. OCP Configuration
Rs1
Cs
Rb
Rt
Cs
Rs1
Rb
IDRP/OCP
Rt
IDRP/OCP
Rocp
Rs2
Rocp
CS+
CS−
CS+
Rs2
CS−
FB
FB
+
−
+
−
Without AVP
Vref
Vref
With AVP
+
+
+
+
G i
G i
I DRP
I DRP
COMP
COMP