TS1583CM5 查看數據表（PDF） - TSC Corporation

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TS1583CM5

1.5A Dual Input LDO

TSC Corporation 

TS1583

1.5A Dual Input LDO

Application Information (Continue)

Stability

The circuit design used in the TS1583 Series requires the use of an output capacitor as part of the device frequency

compensation. The addition of 150uF aluminum electrolytic or a 22uF solid tantalum on the output will ensure stability

for all operating conditions. In order to meet the transient performance of the processor larger value capacitors are

needed. To limit the high frequency noise generated by the processor high quality bypass capacitors must be used. In

order to limit parasitic inductance (ESL) and resistance (ESR) in capacitors to acceptable limits, multiple small ceramic

capacitors in addition to high quality solid tantalum capacitors are required.

When the adjustment terminal is bypass to improve the ripple rejection, the requirement for an output capacitor

increases. The Adjust pin is brought out on the fixed voltage device specifically to allow this capability. To further

improve stability and transient response of these devices larger values of output capacitor can be used. The modern

processors generate large high frequency current transients. The load current step contains higher order frequency

components than the output coupling network must handle until the regulator throttles to the load current level.

Because they contain parasitic resistance and inductance, capacitors are not ideal elements. These parasitic elements

dominate the change in output voltage as the beginning of a transient load step change. The ESR of the output

capacitors produces and instantaneous step in output voltage

ΔV = ΔI (ESR). The ESL of the output capacitors produces a drop proportional to the rate of change of the output

current V = L (ΔI / Δt). the output capacitance produces a change in output voltage proportional to the time until the

regulator can respond ΔV = Δt (ΔI / C).

Output Voltage

The TS1583 (adjustable version) develops a 1.25V reference voltage between the Sense Pin and the Adjust Pin

(Figure 5). Placing a resistor between these two terminals causes a constant current to flow though R1 and down

though R2 to set the output voltage. In general R1 is chosen so that this current is the specified minimum load current

of 10mA. The current out of the Adjust pin is small, typically 50uA and it adds to the current from R1.For best regulation

the top of the resistor divider should be connected directly to the Sense pin.

Figure 5. Setting Output Voltage

Figure 6. Optional Clamp Diodes Protect

Against Input Crowbar Circuits

5/9

Version: A07

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