LTC1871-7_15 Datasheet, PDF (1/34 Pages) Linear Technology – High Input Voltage, Current Mode Boost, Flyback and SEPIC Controller

LTC1871-7
High Input Voltage,
Current Mode Boost,
Flyback and SEPIC Controller
Features
Description
n _{Optimized for High Input Voltage Applications}
n _{Wide Chip Supply Voltage Range: 6V to 36V}
n _{Internal 7V Low Dropout Voltage Regulator}
Optimized for 6V-Rated MOSFETs
n _{Current Mode Control Provides Excellent}
Transient Response
n _{High Maximum Duty Cycle (92% Typ)}
n _{±2% RUN Pin Threshold with 100mV Hysteresis}
n _{±1% Internal Voltage Reference}
n _{Micropower Shutdown: IQ = 10µA}
n _{Programmable Operating Frequency}
(50kHz to 1MHz) with One External Resistor
n _{Synchronizable to an External Clock Up to 1.3 × fOSC}
n _{User-Controlled Pulse Skip or Burst Mode}^® _Operation
n _{Output Overvoltage Protection}
n _{Can be Used in a No RSENSE™ Mode for VDS < 36V}
n _{Small 10-Lead MSOP Package}
Applications
n _{Telecom Power Supplies}
n _{42V Automotive Systems}
n _{24V Industrial Controls}
n _{IP Phone Power Supplies}
The LTC^®1871-7 is a current mode, boost, flyback and
SEPIC controller optimized for driving 6V-rated MOSFETs
in high voltage applications. The LTC1871-7 works equally
well in low or high power applications and requires few
components to provide a complete power supply solution.
The switching frequency can be set with an external resistor
over a 50kHz to 1MHz range, and can be synchronized to
an external clock using the MODE/SYNC pin. Burst Mode
operation at light loads, a low minimum operating supply
voltage of 6V and a low shutdown quiescent current of
10µA make the LTC1871-7 well suited for battery-operated
systems. For applications requiring constant frequency
operation, Burst Mode operation can be defeated using
the MODE/SYNC pin. The LTC1871-7 is available in the
10-lead MSOP package.
PARAMETER
INTV_CC
INTV_CC UV⁺
INTV_CC UV^–
LTC1871-7
7.0V
5.6V
4.6V
LTC1871
5.2V
2.1V
1.9V
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. No R_SENSE is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Typical Application
V_IN
36V TO 72V
604k
26.7k
2.2µF
100V
X7R
100k
D1
9.1V
Q1
FMMT625
10Ω
D3
10BQ060
3:1
V_OUT
12V
0.4A
T1
VP1-0076
47µF
16V
X5R
2.2nF
3.4k
RUN
SENSE
I_TH
V_IN
LTC1871-7
D2
4148
12.4k
110k
120k
FB
FREQ
INTV_CC
GATE
MODE/SYNC GND
4.7µF
X5R
M1
FDC2512
0.1µF
X5R
0.12Ω
18717 F01
Figure 1. Small, Nonisolated 12V Flyback Telecom Housekeeping Supply
18717fd
1