ANP015 Datasheet, PDF (14/15 Pages) List of Unclassifed Manufacturers – Application Note AP2011 High Efficiency Synchronous PWM Controller

Application Note
AP2011 High Efficiency Synchronous PWM Controller
ANP015
Preliminary
4. Design Example
4.1 Summary of Target Specifications
Input Power
V V IN (max) ^{= +20V;} IN (min) ^{= +20V}
Regulated Output Power
V I I = + 5V;
OUT
LOAD(max) ^{= 5A;}
LOAD(min) ^{= 0.5A}
Output Ripple Voltage
Output Voltage Load Regulation
V ≤ 50 mV peak-to-peak
RIPPLE
1% (0.2A to 5A)
Efficiency
87% minimum at full load.
Switching Frequency
F = Virtual Control (180KHz ± 10 %)
4.2 Calculating and Components Selection
Calculation Formula
Select Condition
VOUT=VFB x ((R7/R9) + 1)
L ^{[V V} _I ^{V ] T ≥} (min)
− − × _{IN (min)}
SAT
OUT
2 × _LOAD(min)
ON (max)
I I I ^{= −} PK
LOAD (max)
LOAD (min)
560Ω ≤ R9 ≤ 5KΩ
L(min) ^{≥ 21uH}
I I^{≥ = 4.5A}
rms
PK
VI _ESR
=


2
×
RIPPLE _
 _{LOAD (min)}
V V ^{≥ 1.5×}
WVDC
OUT
I ⁽I I ^{) (} I ^{) =} IN(rms)
δ
×


×
PK
1
m ⁺₃ ^∆
2
L 
V V ≥ 1.5×
WVDC
IN (max)
ESR ≤ 50mΩ
V ≥ 7.5V
WVDC
I I≥
ripple
IN (rms) ^=2.5A
V ≥ 30V
WVDC
Component spec.
R9=1kΩ; R7=3kΩ
Select L2=33uH
Select C12
680uF/16V*1pcs
Select C1
470uF/35V*1pcs
Anachip Corp.
www.anachip.com.tw
14/15
Rev. A.0 Oct, 29, 2004