Datasheet LT1611 (Analog Devices) - 6

LT1611
U OPERATIO
V –(V CESAT IN + VOUT) C2 L1 L2 SW SWX V –V IN OUT Q1 D1 + C1 + C3 RLOAD 1611 F05
Figure 5. Switch-On Phase of Inverting Converter. L1 and L2 Current Have Positive dI/dt
VIN + VOUT+ VD VD C2 L1 L2 SW SWX V –V IN OUT Q1 D1 + C1 + C3 RLOAD 1611 F06
Figure 6. Switch-Off Phase of Inverting Converter. L1 and L2 Current Have Negative dI/dt Transient Response
tions due to load steps and output ripple voltage to very low levels. To illustrate, Figure 7 shows an LT1611 invert- The inverting architecture of the LT1611 can generate a ing converter with resistor loads R very low ripple output voltage. Recently available high L1 and RL2. RL1 is connected across the output, while R value ceramic capacitors can be used successfully in L2 is switched in externally via a pulse generator. Output voltage wave- LT1611 designs with the addition of a phase lead capaci- forms are pictured in subsequent figures, illustrating the tor, CPL (see Figure 7). Connected in parallel with feedback performance of output capacitor type and the effect of C resistor R1, this capacitor reduces both output perturba- PL connected across R1. 6