ANP015 Datasheet, PDF (7/15 Pages) List of Unclassifed Manufacturers – Application Note AP2011 High Efficiency Synchronous PWM Controller

Application Note
AP2011 High Efficiency Synchronous PWM Controller
ANP015
Preliminary
across the inductor and the duration of the VFC_Pulse. A VFC control loop is then formed whereby the
duration of the VFC_Pulse is modified as a result of the FB_Pulse duration. The VFC loop arrives at a state
of equilibrium, where the operating frequency remains inherently constant.
V_IN
ERROR
COMP
Vref
+
-
VFC Pulse
VIRTUAL FREQ
OSCILLATOR
GATE
CONTROL
LOGIC
FB Pulse
Lout
Cout
Vout
Rfb1
Rfb2
D_ON
> 0.1,
240-50 × (1-
V_OUT
V_IN
)
- V_IN
D_ON < 0.1,
10000× VOUT/ VIN
5.9 - 0.01V_IN
Figure 5: Virtual Frequency Control Loop-
Synchronous single supply application.
Virtual frequency control is a technique that provides stable, constant frequency of operation for pulse
controlled architectures such as constant off-time/on-time. This is all done internal to the IC with minimal
number of components and without the need for connections to external terminals such as input and/or
output. No external compensation is required, thus providing a low cost, high performance fix frequency
solution for switching voltage regulators.
Virtual Frequency Control is a trademark of PWRTEK, LLC.
Anachip Corp.
www.anachip.com.tw
Rev. A.0 Oct, 29, 2004
7/15