Datasheet

+
( )
1
C11
2 R8 fc
=
× × ×p
ESR
R Co
C6 =
R4
´
TPS54521
SLVS981C JUNE 2010REVISED AUGUST 2013
www.ti.com
(16)
5. Type III compensation can be implemented with the addition of one capacitor, C11. This allows for slightly
higher loop bandwidths and higher phase margins. If used, C11 is calculated from Equation 17.
(17)
APPLICATION INFORMATION
Design Guide Step-By-Step Design Procedure
This example details the design of a high frequency switching regulator using a Poscap output capacitor and
Type III frequency compensation. A few parameters must be known in order to start the design process.
These parameters are typically determined at the system level. For this example, we start with the following
known parameters:
Table 1.
Parameter Value
Output Voltage 5 V
Output Current 5 A
Transient Response to a 3A load step ΔVout = 1 % (50 mV)
Input Voltage 12 V nominal, 8 V to 17 V
Output Voltage Ripple 1.5% (75 mV p-p)
Start Input Voltage (Rising Vin) 6.806 V
Stop Input Voltage (Falling Vin) 4.824 V
Switching Frequency 700 kHz
Typical Application Schematic
The application schematic of Figure 34 was developed to meet the requirements above. The design procedure is
given in this section. For more information about Type II and Type III frequency compensation circuits, see
Designing Type III Compensation for Current Mode Step-Down Converters (SLVA352) and
Design Calculator (SLVC219).
Figure 34. Typical Application Circuit
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