LTC1871
Wide Input Range, No R
SENSE
Current Mode Boost,
Flyback and SEPIC Controller
FEATURES DESCRIPTION
n
High Ef ciency (No Sense Resistor Required)
The LTC 1871 is a wide input range, current mode, boost,
n
Wide Input Voltage Range: 2.5V to 36V
yback or SEPIC controller that drives an N-channel power
n
Current Mode Control Provides Excellent
MOSFET and requires very few external components. In-
Transient Response
tended for low to medium power applications, it eliminates
n
High Maximum Duty Cycle (92% Typ)
the need for a current sense resistor by utilizing the power
n
2% RUN Pin Threshold with 100mV Hysteresis
MOSFETs on-resistance, thereby maximizing ef ciency.
n
1% Internal Voltage Reference
The ICs operating frequency can be set with an external
n
Micropower Shutdown: I = 10A
Q
resistor over a 50kHz to 1MHz range, and can be syn-
n
Programmable Operating Frequency
chronized to an external clock using the MODE/SYNC
(50kHz to 1MHz) with One External Resistor
pin. Burst Mode operation at light loads, a low minimum
n
Synchronizable to an External Clock Up to 1.3 f
OSC
operating supply voltage of 2.5V and a low shutdown
n
User-Controlled Pulse Skip or Burst Mode Operation
quiescent current of 10A make the LTC1871 ideally suited
n
Internal 5.2V Low Dropout Voltage Regulator
for battery-operated systems.
n
Output Overvoltage Protection
n
For applications requiring constant frequency opera-
Capable of Operating with a Sense Resistor for
tion, Burst Mode operation can be defeated using the
High Output Voltage Applications
n
MODE/SYNC pin. Higher output voltage boost, SEPIC
Small 10-Lead MSOP Package
and yback applications are possible with the LTC1871
by connecting the SENSE pin to a resistor in the source
APPLICATIONS
of the power MOSFET.
n
Telecom Power Supplies
The LTC1871 is available in the 10-lead MSOP package.
n
Portable Electronic Equipment
L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation.
No R is a trademark of Linear Technology Corporation. All other trademarks are the
SENSE
property of their respective owners.
TYPICAL APPLICATION
V
IN
3.3V Ef ciency of Figure 1
L1
100
1H
D1 90
RUN SENSE Burst Mode
V
OUT
80 OPERATION
5V
I V
TH IN
7A
R C
OUT1
C
+ (10A PEAK)
LTC1871 70
22k 150F
PULSE-SKIP
6.3V
FB INTV
CC
MODE
C
C1 R1 4 C 60
OUT2
6.8nF FREQ GATE M1
12.1k
22F
C
IN
1%
C 6.3V
VCC +
R2 R 50
T MODE/SYNC GND 22F
C
C2
4.7F
X5R
37.4k 80.6k
47pF 6.3V
X5R
2
1% 1%
2
40
GND
1871 F01a
30
C : TAIYO YUDEN JMK325BJ226MM D1: MBRB2515L
IN
0.001 0.01 0.1 1 10
C : PANASONIC EEFUEOJ151R L1: SUMIDA CEP125-H 1R0MH
OUT1
OUTPUT CURRENT (A)
C : TAIYO YUDEN JMK325BJ226MM M1: FAIRCHILD FDS7760A
OUT2
1871 F01b
Figure 1. High Ef ciency 3.3V Input, 5V Output Boost Converter (Bootstrapped)
1871fe
1
EFFICIENCY (%)LTC1871
ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION
(Note 1)
TOP VIEW
V Voltage ............................................... 0.3V to 36V
IN
RUN 1 10 SENSE
INTV Voltage ............................................ 0.3V to 7V I 2 9 V
TH IN
CC
FB 3 8 INTV
CC
INTV Output Current .......................................... 50mA
CC FREQ 4 7 GATE
MODE/ 5 6 GND
GATE Voltage ............................ 0.3V to V + 0.3V
INTVCC
SYNC
MS PACKAGE
I , FB Voltages ....................................... 0.3V to 2.7V
TH
10-LEAD PLASTIC MSOP
RUN, MODE/SYNC Voltages ....................... 0.3V to 7V
T = 125C, = 120C/W
JMAX JA
FREQ Voltage ............................................ 0.3V to 1.5V
SENSE Pin Voltage .................................... 0.3V to 36V
Operating Temperature Range (Note 2)
LTC1871E ............................................. 40C to 85C
LTC1871I............................................ 40C to 125C
LTC1871H .......................................... 40C to 150C
Junction Temperature (Note 3)
LTC1871E/LTC1871I ......................................... 125C
LTC1871H .........................................................150C
Storage Temperature Range ................... 65C to 150C
Lead Temperature (Soldering, 10 sec) .................. 300C
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC1871EMS#PBF LTC1871EMS#TRPBF LTSX 10-Lead Plastic MSOP 40C to 85C
LTC1871IMS#PBF LTC1871IMS#TRPBF LTBFC 10-Lead Plastic MSOP 40C to 125C
LTC1871HMS#PBF LTC1871HMS#TRPBF LTCXS 10-Lead Plastic MSOP 40C to 150C
LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC1871EMS LTC1871EMS#TR LTSX 10-Lead Plastic MSOP 40C to 85C
LTC1871IMS LTC1871IMS#TR LTBFC 10-Lead Plastic MSOP 40C to 125C
LTC1871HMS LTC1871HMS#TR LTCXS 10-Lead Plastic MSOP 40C to 150C
Consult LTC Marketing for parts speci ed with wider operating temperature ranges.
For more information on lead free part marking, go to: