NCP4201MNR2G ON Semiconductor, NCP4201MNR2G Datasheet - Page 13

• Manufacturer Part Number: NCP4201MNR2G
• Description: IC CTLR VR11.1 4PH PMBUS ITF
• Manufacturer: ON Semiconductor

Specifications of NCP4201MNR2G

• Applications: Controller, Intel VR11, VR11.1
• Voltage - Input: 1.7 ~ 24 V
• Number Of Outputs: 4
• Voltage - Output: 0.375 ~ 1.6 V
• Operating Temperature: 0°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The current limit and the load−line can be adjusted from the
circuit component values over the PMBus.
Current Limit Set−Point
programmed by a resistor between the I
CSCOMP pin. The I
with an internal current reference of 20 mA. If I
exceeds 20 mA then the output current has exceeded the limit
and the current limit protection is tripped.
Where V
Assuming that:
the R
Assuming we want a current limit of 150 A that means that
I
Solving this equation for R
resistor programmed value by using the PMBus interface
using Bits <4:0> of the Current Limit Threshold command
(0xE2). The limit is programmable between 50% of the
external limit and 146.7% of the external limit. The
resolution is 3.3%. Table 3 gives some examples codes.
Current Limit, Short−Circuit and Latchoff Protection
internal latchoff delay time will start, and the controller will
shut down if the fault is not removed. This delay is four times
LIMFS
Table 3. Current Limit
The CPU current can also be monitored over the PMBus.
The current limit threshold on the NCP4201 is
i.e. the external circuit is set up for a 1 mW load−line then
The current limit threshold can be modified from the
If the current limit is reached and TD5 has completed, an
ILIMFS
0 0000
0 0001
1 0000
1 0001
1 1110
1 1111
must equal 20 mA at that load.
Code
I
ILIMFS
I
V
ILIMFS
ILIMFS
CSREF
20 mA +
I
is calculated as follows:
ILIMFS
R
R
+
+
= V
* V
CS
PH
V
V
+
ILIMFS
CSREF
CSREF
1 mW
CSCOMP
LIMFS
1 mW
R
Current Limit (% of External Limit)
R
L
R
R
R
ILIMITFS
* V
+ 1 mW
ILIMITFS
ILIMFS
* V
ILIMFS
LIMITFS
current, I
150 A
+
CSCOMP
I
CSCOMP
LOAD
100% = default
R
R
CS
PH
we get 7.5 kW.
103.3%
143.3%
146.7%
+ 7.5 kW
53.3%
50%
ILIMFS
R
LIMFS
L
, is compared
I
LOAD
pin and the
(eq. 4)
(eq. 1)
(eq. 2)
(eq. 5)
http://onsemi.com
ILIMFS
(eq. 3)
13
longer than the delay time during the startup sequence. The
current limit delay time only starts after TD5 has completed.
If there is a current limit during startup, the NCP4201 will
go through TD1 to TD5 and then start the latchoff time.
Because the controller continues to cycle the phases during
the latchoff delay time, if the short is removed before the
timer is complete, the controller can return to normal
operation.
reapplying the supply voltage to the NCP4201, or by
toggling the EN pin low for a short time.
a secondary current limit is active. This is necessary because
the voltage swing of CSCOMP cannot go below ground.
This secondary current limit limits the internal COMP
voltage to the PWM comparators to 1.5 V. This limits the
voltage drop across the low−side MOSFETs through the
current balance circuitry. Typical overcurrent latchoff
waveforms are shown in Figure 9.
phases if one or more phases stop functioning because of a
faulty component. This limit is based on the maximum
normal mode COMP voltage.
Output Current Monitor
the total current being delivered to the load. It outputs an
accurate current that is directly proportional to the current
set by the I
from the I
accurately scaled and filtered voltage as per the
specification. The size of the resistor is used to set the I
scaling.
current of the processor. This means that the R
should be chosen as follows.
The latchoff function can be reset by either removing/
During startup when the output voltage is below 200 mV,
An inherent per phase current limit protects individual
I
The current is then run through a parallel RC connected
The scaling is set such that I
MON
Figure 9. Overcurrent Latchoff Waveforms
is an analog output from the NCP4201 representing
LIMFS
MON
pin to the FBRTN pin to generate an
resistor.
I
IMON
+ 10
MON
I
= 900 mV at the TDC
ILIMFS
IMON
resistor
(eq. 6)
MON