FEATURES
s Wide VIN Range: 1.9V to 18V
s 300kHz Fixed Frequency Current Mode Control
s 1A Rail-to-Rail N-Channel MOSFET Driver
s Low 53mV Current Limit Threshold Voltage
Improves Efficiency
s Implements Boost, SEPIC and Flyback Converters
Requiring Low Side Power Transistors
s Internal Current Sense Amplifier
with Leading Edge Blanking
s Up to 500kHz External Synchronization
s Burst Mode® Operation for High Efficiency
at Light Load
s 140µA Quiescent Current
s 15µA Shutdown Current
s 8-Lead MSOP and SO Packages
U
APPLICATIO S
s 3.3V to 5V DC/DC Converters
s Distributed Power Supplies
s Isolated Power Supplies
LT1619
Low Voltage Current Mode
PWM Controller
DESCRIPTIO
The LT®1619 is a fixed frequency PWM controller for
implementing current mode DC/DC converters with mini-
mum 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 con-
verters. 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.
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 exter-
nally up to 500kHz. No load quiescent current is 140µA and
shutdown current is 15µA.
The LT1619 is available in 8-lead MSOP and SO packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
VIN
3.3V
37.4k
12.4k
220pF
75k
15nF
1
S/S
8
VIN
2
FB
7
DRV
LT1619
36
VC GATE
45
GND SENSE
C1: PANASONIC EEFCDOK220R
COUT: KEMET T495X227K010AS (×2)
D1: MBRD835L
L1: COILCRAFT DO5022P-562
+
0.1µF
C1
22µF
0.1µF
L1
5.6µH
5A
M1
Si9804
D1
+
RSENSE
0.01Ω
1619 F01
VOUT
5V
2.2A
COUT
440µF
Figure 1. High Efficiency 3.3V to 5V DC/DC Converter
Efficiency
95
90
85
80
75
70
1
10 100
LOAD CURRENT (mA)
1000
1619 F01a
1619fa
1
