IR3513Z International Rectifier Corp., IR3513Z Datasheet - Page 19

• Manufacturer Part Number: IR3513Z
• Description: Xphase3tm Pol Control Ic
• Manufacturer: International Rectifier Corp.

Linear Regulator Output (VCCL)
The IR3513Z has a built-in linear regulator controller, and only an external NPN transistor is needed to create a linear
regulator. The output voltage can be programmed between 4.75V and 7V by the resistor divider at VCCLFB pin. The
regulator output powers the gate drivers of the phase ICs and circuits in the control IC, and the voltage is usually
programmed to optimize the converter efficiency. The linear regulator can be compensated by a 4.7uF capacitor at the
VCCL pin. As with any linear regulator, due to stability reasons, there is an upper limit to the maximum capacitor value
that can be used at this pin and it is a function of the number of phases used in the multiphase architecture and their
switching frequency. Figure 10 shows the stability plots for the linear regulator with 5 phases switching at 750 kHz.
Page 19
VRRDY
ENABLE
SS/DEL
IOUT
VOUT
EA
OCP THRESHOLD
3.12V
3.08V
3.2V
1.4V
Figure 9 - Constant over-current control waveforms during and after soft start
Figure 10 - VCCL regulator stability with 5 phases and PHSOUT equals 750 kHz
START-UP WITH
OUTPUT SHORTED
HICCUP OVER-CURRENT
PROTECTION (OUTPUT
SHORTED)
NORMAL
START-UP
NORMAL
OPERATION
(OUTPUT
SHORTED)
OCP
DELAY
OVER-CURRENT
PROTECTION
(OUTPUT SHORTED)
NORMAL
START-UP
May 11, 2009
NORMAL
OPERATION
IR3513Z
POWER-DOWN