PM6652 STMicroelectronics, PM6652 Datasheet - Page 39

• Manufacturer Part Number: PM6652
• Description: IC CTLR STEPDOWN SMPS 32VFQFPN
• Manufacturer: STMicroelectronics

Specifications of PM6652

• Applications: Controller, Intel IMVP-6.5™, VR11
• Voltage - Input: 4.5 V ~ 36 V
• Number Of Outputs: 1
• Voltage - Output: 0.3 V ~ 1.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 32-VFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PM6652
8.10.6
Overcurrent protection
The PM6652 controller can limit the maximum load current by skipping one or more
switching cycles if the valley current limit is detected. The current limit sensing is
independent from the current sensing for droop and IMON functions. Basically, the voltage
drop sensed between PGND and PHASE pins, when the low side MOSFET is on, is
compared with the voltage across the external R
program the valley current limit value (see
Equation 20
Figure 41. Valley current limit circuitry
The maximum programmable voltage on pin ILIM is 3.5 V (typ.); as a consequence the
maximum effective RILIM resistor is about 700 kΩ.
If, starting from the previous equation, an higher resistance is required the resultant low side
MOSFET on-resistance is not adequate for the designed application.
The maximum available load current, with the valley current limit technique, is equal to:
Equation 21
i.e. the maximum available current is the sum of the valley current limit value plus the half of
the inductor current ripple. The valley current limit is sensed each switching cycle, during
T
the typical behavior is the one shown in
OFF
time (when the low-side MOSFET is turned-on). This fault protection is not latched but
R
Doc ID 16867 Rev 3
ILIM
I
⋅
LOAD
5
μ
A
,
MAX
=
Figure 42 on page 40
20
Figure 41
=
⋅
I
(
VCL
V
PGND
ILIM
+
resistor. The following equation helps to
1
2
):
−
Δ ⋅
V
I
PHASE
L
)
:
Device description
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