LM2576SX-5.0 View Datasheet(PDF) - Unspecified
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Description
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LM2576SX-5.0 Datasheet PDF : 23 Pages
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LM2576/LM2576HV
Definition of Terms (Continued)
CAPACITOR EQUIVALENT SERIES RESISTANCE (ESR)
The purely resistive component of a real capacitor’s impedance
( see Figure 16 ). It causes power loss resulting in capacitor
heating ,which directly affects the capacitor’s operating lifetime.
When used as a switching regulator output filter, higher ESR
values result in higher output ripple voltages.
dependent upon the type of core, the core area, the number of
turns, and the duty cycle.
Connection Diagrams (Note 15)
Straight Leads
5-Lead TO-220(T)
Top View
FIGURE 16. Simple Model of a Real Capacitor
Most standard aluminum electrolytic capacitors in the 100μF
-1000 μ F range have 0.5 Ω to 0.1 Ω ESR. Higher-grade
capacitors (“low-ESRâ€, “high-frequencyâ€, or “low-inductanceâ€) in
the 100μF -1000μF range generally have ESR of less than
0.15Ω.
EQUIVALENT SERIES INDUCTANCE (ESL)
The pure inductance component of a capacitor ( see Figure 16 ).
The amount of inductance is determined to a large extent on the
capacitor’s construction. In a buck regulator, this unwanted
inductance causes voltage spikes to appear on the output.
OUTPUT RIPPLE VOLTAGE
The AC component of the switching regulator’s output voltage.
It is usually dominated by the output capacitor’s ESR multiplied
by the inductor’s ripple current (△I IND ). The peak-to-peak
value of this sawtooth ripple current can be determined by
reading the Inductor Ripple Current section of the Application
hints.
CAPACITOR RIPPLE CURRENT
RMS value of the maximum allowable alternating current at
which a capacitor can be operated continuously at a specified
temperature.
STANDBY QUIESCENT CURRENT (ISTBY)
Supply current required by the LM2576 when in the standby
mode ( /OFF pin is driven to TTL-high voltage, thus turning
the output switch OFF).
INDUCTOR RIPPLE CURRENT (â–³I IND)
The peak-to-peak value of the inductor current waveform,
typically a sawtooth waveform when the regulator is operating
in the continuous mode (vs. discontinuous mode).
CONTINUOUS/DISCONTINUOUS MODE OPERATION
Relates to the inductor current. In the continuous mode, the
inductor current is always flowing and never drops to zero, vs.
the discontinuous mode, where the inductor current drops to
zero for a period of time in the normal switching cycle.
INDUCTOR SATURATION
The condition which exists when an inductor cannot hold any
more magnetic flux. When an inductor saturates, the inductor
appears less inductive and the resistive component dominates.
Inductor current is then limited only by the DC resistance of the
wire and the available source current.
OPERATING VOLT MICROSECOND CONSTANT (Eâ—Top)
The product (in Voltâ—μs) of the voltage applied to the inductor
and the time the voltage is applied. This Eâ—Top constant is a
measure of the energy handling capability of an inductor and is
01147621
LM2576T-XX or LM2576HVT-XX
NS Package Number T05A
TO-263(S)
5-Lead Surface-Mount Package
Top View
LM2576S-XX or LM2576HVS-XX
NS Package Number TS5B
LM2576SX-XX or LM2576HVSX-XX
NS Package Number TS5B, Tape and Reel
Bent, Staggered Leads
5-Lead TO-220 (T)
Top View
Side View
LM2576T-XX Flow LB03
Or LM2576HVT-XX Flow LB03
NS Package Number T05D
Note15:(XX indicates output voltage option. See ordering
information table for complete part number.)
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