LT1913EDD#PBF Linear Technology, LT1913EDD#PBF Datasheet - Page 15

• Manufacturer Part Number: LT1913EDD#PBF
• Description: IC REG STEP DOWN 3.5A 10-DFN
• Manufacturer: Linear Technology
• Type: Step-Down (Buck)r

Specifications of LT1913EDD#PBF

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 0.79 ~ 25 V
• Current - Output: 3.5A
• Frequency - Switching: 200kHz ~ 2.4MHz
• Voltage - Input: 3.6 ~ 25 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 10-DFN
• Primary Input Voltage: 25V
• No. Of Outputs: 1
• Output Voltage: 25V
• Output Current: 3.5A
• No. Of Pins: 10
• Operating Temperature Range: -40°C To +125°C
• Msl: MSL 1 - Unlimited
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -

APPLICATIONS INFORMATION
more than 2.3V above the SW pin for best effi ciency. For
outputs of 3V and above, the standard circuit (Figure 4a)
is best. For outputs between 2.8V and 3V, use a 1μF boost
capacitor. A 2.5V output presents a special case because it
is marginally adequate to support the boosted drive stage
while using the internal boost diode. For reliable BOOST pin
operation with 2.5V outputs use a good external Schottky
diode (such as the ON Semi MBR0540), and a 1μF boost
capacitor (see Figure 4b). For lower output voltages the
boost diode can be tied to the input (Figure 4c), or to
another supply greater than 2.8V. The circuit in Figure 4a
Figure 4. Three Circuits For Generating The Boost Voltage
4.7μF
4.7μF
4.7μF
V
V
V
IN
IN
IN
(4b) For 2.5V < V
V
V
V
IN
IN
IN
(4a) For V
(4c) For V
LT1913
LT1913
LT1913
GND
GND
GND
BD
BD
BD
BOOST
BOOST
BOOST
SW
SW
SW
OUT
OUT
OUT
< 2.5V
> 2.8V
< 2.8V
C3
C3
C3
D2
1913 FO4
V
OUT
V
V
OUT
OUT
is more effi cient because the BOOST pin current and BD
pin quiescent current comes from a lower voltage source.
You must also be sure that the maximum voltage ratings
of the BOOST and BD pins are not exceeded.
The minimum operating voltage of an LT1913 application
is limited by the minimum input voltage (3.6V) and by the
maximum duty cycle as outlined in a previous section. For
proper startup, the minimum input voltage is also limited
by the boost circuit. If the input voltage is ramped slowly,
or the LT1913 is turned on with its RUN/SS pin when the
output is already in regulation, then the boost capacitor
may not be fully charged. Because the boost capacitor is
Figure 5. The Minimum Input Voltage Depends on
Output Voltage, Load Current and Boost Circuit
6.0
5.5 TO START
5.0
4.5
4.0
3.5
3.0
2.5
2.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1
1
TO RUN
V
T
L = 8.2μH
f = 600kHz
TO RUN
V
T
L = 8.2μH
f = 600kHz
(WORST CASE)
TO START
(WORST CASE)
A
A
OUT
OUT
= 25°C
= 25°C
= 3.3V
= 5V
10
10
LOAD CURRENT (mA)
LOAD CURRENT (mA)
100
100
1000
1000
1913 F05
10000
10000
LT1913
15
1913f