LT1611CS5 datasheet(6/12 Pages) LINER

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LT1611

Transient Response

The inverting architecture of the LT1611 can generate a

very low ripple output voltage. Recently available high

value ceramic capacitors can be used successfully in

LT1611 designs with the addition of a phase lead capaci-

tor, CPL (see Figure 7). Connected in parallel with feedback

resistor R1, this capacitor reduces both output perturba-

OPERATIO

tions due to load steps and output ripple voltage to very

low levels. To illustrate, Figure 7 shows an LT1611 invert-

ing converter with resistor loads RL1 and RL2. RL1 is

connected across the output, while RL2 is switched in

externally via a pulse generator. Output voltage wave-

forms are pictured in subsequent figures, illustrating the

performance of output capacitor type and the effect of CPL

connected across R1.

–(VIN + VOUT)

SWX

1611 F05

RLOAD

–VOUT

VIN

VCESAT

VIN + VOUT+ VD

SWX

1611 F06

RLOAD

–VOUT

VIN

Figure 5. Switch-On Phase of Inverting Converter. L1 and L2 Current Have Positive dI/dt

Figure 6. Switch-Off Phase of Inverting Converter. L1 and L2 Current Have Negative dI/dt

LT1611CS5 Datasheet(PDF) 6 Page - Linear Technology