LT1933ES6#PBF Linear Technology, LT1933ES6#PBF Datasheet - Page 13

• Manufacturer Part Number: LT1933ES6#PBF
• Description: IC, STEP-DOWN REGULATOR, 6-TSOT-23
• Manufacturer: Linear Technology

Specifications of LT1933ES6#PBF

• Primary Input Voltage: 36V
• No. Of Outputs: 1
• Output Current: 600mA
• No. Of Pins: 6
• Operating Temperature Range: -40°C To +85°C
• Supply Voltage Range: 3.6V To 36V
• Switching Frequency Max: 600kHz
• Msl: MSL 1 - Unlimited
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS INFORMATION
Shorted and Reversed Input Protection
If the inductor is chosen so that it won’t saturate exces-
sively, an LT1933 buck regulator will tolerate a shorted
output. There is another situation to consider in systems
where the output will be held high when the input to the
LT1933 is absent. This may occur in battery charging ap-
plications or in battery backup systems where a battery
or some other supply is diode OR-ed with the LT1933’s
output. If the V
is held high (either by a logic signal or because it is tied
to V
quiescent current through its SW pin. This is fi ne if your
system can tolerate a few mA in this state. If you ground
the SHDN pin, the SW pin current will drop to essentially
zero. However, if the V
is held high, then parasitic diodes inside the LT1933 can
pull large currents from the output through the SW pin
IN
), then the LT1933’s internal circuitry will pull its
IN
pin is allowed to fl oat and the SHDN pin
IN
pin is grounded while the output
Figure 5. Diode D4 Prevents a Shorted Input from Discharging a Backup
Battery Tied to the Output; It Also Protects the Circuit from a Reversed
Input. The LT1933 Rns Only When the Input is Present
V
IN
D4: MBR0540
D4
V
SHDN
IN
GND
LT1933
BOOST
FB
SW
and the V
when the input voltage is present and that protects against
a shorted or reversed input.
Hot Plugging Safely
The small size, robustness and low impedance of ceramic
capacitors make them an attractive option for the input
bypass capacitor of LT1933 circuits. However, these capaci-
tors can cause problems if the LT1933 is plugged into a
live supply (see Linear Technology Application Note 88 for
a complete discussion). The low loss ceramic capacitor
combined with stray inductance in series with the power
source forms an under damped tank circuit, and the voltage
at the V
input voltage, possibly exceeding the LT1933’s rating and
damaging the part. If the input supply is poorly controlled
or the user will be plugging the LT1933 into an energized
supply, the input network should be designed to prevent
this overshoot.
IN
IN
pin of the LT1933 can ring to twice the nominal
pin. Figure 5 shows a circuit that will run only
1933 F05
BACKUP
V
OUT
LT1933
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