1
LT1619
1619fa
Low Voltage Current Mode
PWM Controller
, LTC and LT are registered trademarks of Linear Technology Corporation.
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.
■
Wide V
IN
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
■
3.3V to 5V DC/DC Converters
■
Distributed Power Supplies
■
Isolated Power Supplies
Figure 1. High Efficiency 3.3V to 5V DC/DC Converter
Burst Mode is a registered trademark of Linear Technology Corporation.
LOAD CURRENT (mA)
75
EFFICIENCY (%)
80
85
90
95
1 100 1000
1619 F01a
70
10
Efficiency
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
+
0.1µF
0.1µF
15nF
220pF
V
IN
3.3V
L1
5.6µH
5A
D1
M1
Si9804
V
OUT
5V
2.2A
R
SENSE
0.01Ω
1619 F01
75k
37.4k
12.4k
C1
22µF
C1: PANASONIC EEFCDOK220R
C
OUT
: KEMET T495X227K010AS (×2)
D1: MBRD835L
L1: COILCRAFT DO5022P-562
+
C
OUT
440µF
S/S
FB
V
C
GND
8
7
6
5
1
2
3
4
V
IN
DRV
GATE
SENSE
LT1619