LT1616ES6#TRM Linear Technology, LT1616ES6#TRM Datasheet - Page 11

• Manufacturer Part Number: LT1616ES6#TRM
• Description: IC SW REG STEP-DN 1.4MHZ SOT23-6
• Manufacturer: Linear Technology
• Type: Step-Down (Buck)r

Specifications of LT1616ES6#TRM

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 3.3V, 5V
• Current - Output: 600mA
• Frequency - Switching: 1.4MHz
• Voltage - Input: 3.6 ~ 25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-6
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -
• Other names: LT1616ES6#TRMTR

APPLICATIO S I FOR ATIO
Shorted Input Protection
If the inductor is chosen so that it won’t saturate exces-
sively, an LT1616 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
LT1616 is absent. This may occur in battery charging
applications or in battery backup systems where a battery
or some other supply is diode OR-ed with the LT1616’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 fine if your
system can tolerate a few mA in this state. If you ground
Figure 8. Subtracting the Current When the Switch is On (a) from the Current When the Switch is Off (b) Reveals the Path of the High
Frequency Switching Current (c). Keep This Loop Small. The Voltage on the SW and BOOST Nodes Will Also be Switched; Keep These
Nodes as Small as Possible. Finally, Make Sure the Circuit is Shielded with a Local Ground Plane
IN
), then the LT1616’s internal circuitry will pull its
IN
pin is allowed to float and the SHDN pin
U
U
V
Figure 7. 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 LT1616 Runs Only When the Input is Present
IN
I
C1
V
GND
IN
SW
W
(a)
D4: MBR0530
100k
100k
D4
5
4
C1
V
SHDN
IN
GND
U
2
LT1616
BOOST
FB
V
IN
SW
3
GND
1
6
SW
(c)
the SHDN pin, the SW pin current will drop to essentially
zero. However, if the V
is held high, then parasitic diodes inside the LT1616 can
pull large currents from the output through the SW pin and
the V
the input voltage is present and that protects against a
shorted or reversed input.
PCB Layout
For proper operation and minimum EMI, care must be
taken during printed circuit board layout. Figure 8 shows
the high current paths in the buck regulator circuit. Note
that large, switched currents flow in the power switch, the
IN
pin. Figure 7 shows a circuit that will run only when
D1
L1
1616 F07
V
IN
GND
C2
1616 F08
V
V
BACKUP
SW
SW
OUT
(b)
IN
pin is grounded while the output
LT1616
11