AND8079 Datasheet, PDF (12/20 Pages) ON Semiconductor – A Low Cost DDR Memory Power Supply Using the NCP1571 Synchronous Buck Converter and a LM358 Based Linear Voltage Regulator

AND8079/D
Channel 1: 5.0 V Input Voltage
Channel 2: Transient current load of I_Vdd = 0 to 8.0 A
Figure 20. Switching Noise Reflected to the 5.0 V Input Power Supply with a Transient Load I_Vdd = 0 to 8.0 A,
I_Vtt = 0 to 4.0 A Sourcing (i.e. –2.0 A Sinking to +2.0 A Sourcing Transient Current Load) and V_REF = 2.45 mA
Table 1: Component temperature measured in still air at an
ambient temperature of 23_C. The load conditions were:
1. V_dd Transient current load I_Vdd = 0 to 8.0 A
2. V_tt Transient current load I_Vtt = 0 to 4.0 A
sourcing (i.e. –2.0 A sinking to +2.0 A sourcing
transient current load)
3. Steady state V_REF current load I_REF = 2.5 mA
Table 1.
Circuit
V_dd
V_dd
V_dd
V_dd
V_dd
V_dd
V_dd
V_dd
V_tt
V_tt
V_tt
Component
FET Diode (Q₁)
Top FET (Q₂)
Bottom FET (Q₃)
Input Inductor (L₁)
Output Inductor (L₂)
Input Capacitor (C₂)
Output Capacitor (C₁₀)
NCP1571 (U₁)
LM358 (U₂)
Top FET (Q₄)
Bottom FET (Q₅)
Temperature (5C)
41.6
54.2
56.4
42.1
57.9
33.0
31.2
55.0
46.2
42.1
49.3
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