LTC1266 Datasheet, PDF (1/20 Pages) Linear Technology – Synchronous Regulator Controller for N- or P-Channel MOSFETs

LTC1266
LTC1266-3.3/LTC1266-5
Synchronous Regulator
Controller for
N- or P-Channel MOSFETs
FEATURES
DESCRIPTIO
s _{Ultrahigh Efficiency: Over 95% Possible}
s _{Drives N-Channel MOSFET for High Current or}
P-Channel MOSFET for Low Dropout
s _{Pin Selectable Burst Mode Operation}
s _{1% Output Accuracy (LTC1266A)}
s _{Pin Selectable Phase of Topside Driver for Boost}
or Step-Down Operation
s _{Wide VIN Range: 3.5V to 20V}
s _{On-Chip Low-Battery Detector}
s _{High Efficiency Maintained Over Large Current Range}
s _{Low 170µA Standby Current at Light Loads}
s _{Current Mode Operation for Excellent Line and Load}
Transient Response
s _{Logic Controlled Micropower Shutdown: IQ < 40µA}
s _{Short-Circuit Protection}
s _{Synchronous Switching with Nonoverlaping Gate Drives}
s _{Available in 16-Pin Narrow SO Package}
U
APPLICATIO S
s _{Notebook and Palmtop Computers}
s _{Portable Instruments}
s _{Cellular Telephones}
s _{DC Power Distribution Systems}
s _{GPS Systems}
The LTC^®1266 series is a family of synchronous switching
regulator controllers featuring automatic Burst Mode^TM
operation to maintain high efficiencies at low output
currents. These devices drive external power MOSFETs at
switching frequencies up to 400kHz using a constant off-
time current mode architecture providing constant ripple
current in the inductor. They can drive either an N-channel
or a P-channel topside MOSFET.
The operating current level is user-programmable via an
external current sense resistor. Wide input supply range
allows operation from 3.5V to 18V (20V maximum).
Constant off-time architecture provides low dropout regu-
lation limited only by the R_DS(ON) of the topside MOSFET
(when using the P-channel) and the resistance of the
inductor and current sense resistor.
The LTC1266 series combines synchronous switching for
maximum efficiency at high currents with an automatic
low current operating mode, called Burst Mode operation,
which reduces switching losses. Standby power is re-
duced to only 1mW at V_IN = 5V (at I_OUT = 0). Load currents
in Burst Mode operation are typically 0mA to 500mA.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
V_IN
4V TO 9V ₊
C_IN
100µF
×2
LOW BAT IN
0V = NORMAL
>1.5V = SHUTDOWN
R_C
470Ω
C_C
3300pF
C_T
180pF
*TOKO 919AS-4R7M
V_IN
LB_IN
PWR V_IN
LB_OUT
PINV
TDRIVE
LTC1266-3.3
SHDN SENSE⁺
I_TH
C_T
BINH
SENSE ^–
BDRIVE
SGND PGND
D2
MBR0530T1
N-CHANNEL
Si9410
1000pF
N-CHANNEL
Si9410
C_B
0.1µF
LOW BAT OUT
100k
L*
R_SENSE
5µH 0.02Ω
V_OUT
3.3V
5A
+
D1
MBRS130LT3
1266 TA01
C_OUT
330µF
×2
Figure 1. High Efficiency Step-Down Converter
LTC1266-3.3 Efficiency
100
V_IN = 5V
95
90
85
80
0.01
0.1
1
LOAD CURRENT (A)
5
1266 TA02
1