LT1619
Low Voltage Current Mode
PWM Controller
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FEATURES
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DESCRIPTIO
The LT ®1619 is a fixed frequency PWM controller for
implementing current mode DC/DC converters with minimum external parts. The LT1619 operates with input
voltages ranging from 1.9V to 18V and is suitable for a
variety of battery-powered and distributed DC/DC converters. The internal rail-to-rail N-channel MOSFET driver
operates either from the input in the nonbootstrapped
mode or from the output in bootstrapped operation. The
driver is designed to drive a low side power transistor in
boost, SEPIC, flyback and other topologies.
Wide VIN Range: 1.9V to 18V
300kHz Fixed Frequency Current Mode Control
1A Rail-to-Rail N-Channel MOSFET Driver
Low 53mV Current Limit Threshold Voltage
Improves Efficiency
Implements Boost, SEPIC and Flyback Converters
Requiring Low Side Power Transistors
Internal Current Sense Amplifier
with Leading Edge Blanking
Up to 500kHz External Synchronization
Burst Mode® Operation for High Efficiency
at Light Load
140µA Quiescent Current
15µA Shutdown Current
8-Lead MSOP and SO Packages
Converter efficiency is improved at heavy loads with a
53mV current sense voltage and at light load with Burst
Mode operation. The operating frequency is internally set
at 300kHz. The oscillator can also be synchronized externally up to 500kHz. No load quiescent current is 140µA and
shutdown current is 15µA.
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APPLICATIO S
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The LT1619 is available in 8-lead MSOP and SO packages.
3.3V to 5V DC/DC Converters
Distributed Power Supplies
Isolated Power Supplies
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
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TYPICAL APPLICATIO
Efficiency
VIN
3.3V
12.4k
2
3
75k
220pF
4
VIN
S/S
FB
DRV
LT1619
VC
GATE
GND
15nF
SENSE
8
7
6
+
0.1µF
C1
22µF
90
L1
5.6µH
5A
VOUT
5V
2.2A
0.1µF
M1
Si9804
5
D1
+
RSENSE
0.01Ω
C1: PANASONIC EEFCDOK220R
COUT: KEMET T495X227K010AS (×2)
D1: MBRD835L
L1: COILCRAFT DO5022P-562
1619 F01
COUT
440µF
EFFICIENCY (%)
1
37.4k
95
85
80
75
70
1
10
100
LOAD CURRENT (mA)
1000
1619 F01a
Figure 1. High Efficiency 3.3V to 5V DC/DC Converter
1619fa
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