IR3521MTRPBF International Rectifier, IR3521MTRPBF Datasheet - Page 32

• Manufacturer Part Number: IR3521MTRPBF
• Description: IC CTRL XPHASE3 SVID 32-MLPQ
• Manufacturer: International Rectifier
• Series: XPhase3™r

Specifications of IR3521MTRPBF

• Applications: Processor
• Current - Supply: 10mA
• Voltage - Supply: 4.75 V ~ 7.5 V
• Operating Temperature: 0°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: *
• Package: 32-Lead MLPQ
• Circuit: X-Phase Control IC
• Switch Freq (khz): 250kHz to 1.5MHz
• Pbf: PbF Option Available
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

When a step load is applied, the capacitor acts as a short-circuit, at that instant, and pushes the OCSET signal up by
∆V (i.e. change in IIN) instantaneously. After an increase in its level, the OCP signal starts decaying exponentially
towards its original value. The rate of decay is determined by the RC time constant. The VR will enter hiccup mode
when the OCSET signal falls below the IIN value. The following equation (18) is use to calculate the ideal capacitor
value:
where,
The following graph shows a dynamic OC response with t
C
IDD
OC Threshold
OC Threshold
_
IDD_Spike Boundary
IDD_Spike Boundary
TDC
TDC
Spike
t
R
I
I
I
spike_oc
spike
OC
TDC
Figure 20 Showing Dynamic OC Response
oc


= Thermal Design Current.
= IDD_Spike Max,
= TDC OC Threshold,
= IDD_Spike OC time (choose >1.5ms),
= OC resistor (TDC),
R
OC
tspike_oc
tspike_oc

t
In
spike
I
I
_
spike
spike
oc
Page 32


Figure X:
I
I
IDD_Spike OC Threshold
IDD_Spike OC Threshold
TDC
OC
,
spike
set for 1.5ms.
(18)
IR3521
V3.03