Document
U U
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 ModeTM operation to maintain high efficiencies at low output currents. These devices drive external power MOSFETs at switching frequencies up to 400kHz using a constant offtime 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 regulation limited only by the RDS(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 reduced to only 1mW at VIN = 5V (at IOUT = 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
VIN
4V TO 9V +
CIN 100µF
×2
LOW BAT IN
0V = NORMAL >1.5V = SHUTDOWN
RC 470Ω
CC 3300pF
CT 180pF
*TOKO 919AS-4R7M
VIN LBIN
PWR VIN LBOUT
PINV
TDRIVE
LTC1266-3.3
SHDN SENSE+
ITH CT BINH
SENSE – BDRIVE
SGND PGND
D2 MBR0530T1
N-CHANNEL Si9410
1000pF
N-CHANNEL Si9410
CB 0.1µF
LOW BAT OUT 100k
L* RSENSE 5µH 0.02Ω
VOUT 3.3V
5A
+
D1 MBRS130LT3
1266 TA01
COUT 330µF
×2
Figure 1. High Efficiency Step-Down Converter
EFFICIENCY (%)
LTC1266-3.3 Efficiency
100 VIN = 5V
95
90
85
80 0.01
0.1 1 LOAD CURRENT (A)
5
1266 TA02
1
U WW W
LTC1266 LTC1266-3.3/LTC1266-5
ABSOLUTE AXI U RATI GS
(Note 1)
Input Supply Voltage (Pins 2, 5) ............... 20V to – 0.3V Continuous Output Current (Pins 1, 16) .............. 50mA Sense Voltages (Pins 8, 9) ....................... 13V to – 0.3V SHDN Voltage (Pin 11) ............................. 12V to – 0.3V PINV, BINH, LBIN (Pins 3, 4, 13)................20V to – 0.3V LBOUT Output Current ........................................... 12mA Operating Ambient Temperature Range ...... 0°C to 70°C Industrial Temperature Range ................ – 40°C to 85°C Extended Commercial
Temperature Range ........................... – 40°C to 85°C Junction Temperature (Note 2) ............................ 125°C Storage Temperature Range ................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec)................. 300°C
UW U PACKAGE/ORDER I FOR ATIO
TOP VIEW
TDRIVE 1 PWR VIN 2
PINV 3 BINH 4
VIN 5 CT 6 ITH 7 SENSE– 8
16 BDRIVE 15 PGND 14 LBOUT 13 LBIN 12 SGND 11 SHDN 10 VFB (NC*) 9 SENSE+
S PACKAGE 16-LEAD PLASTIC SO
*FIXED OUTPUT VERSIONS
TJMAX = 125°C, θJA = 110°C/ W
ORDER PART NUMBER
LTC1266CS LTC1266CS-3.3 LTC1266CS-5 LTC1266ACS LTC1266IS LTC1266IS-3.3 LTC1266IS-5 LTC1266AIS
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS The q denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 10V, VSHDN = VBINH = 0V unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX
VFB Feedback Voltage
LTC1266ACS LTC1266CS
VIN = 9V, ILOAD = 700mA, VPINV = VPWR = 14V, Topside Switch = N-Ch
q 1.252 1.265 1.278 q 1.210 1.265 1.290
IFB Feedback Current (LTC1266 Only)
VOUT Regulated Output Voltage
LTC1266CS-3.3 LTC1266CS-5
VIN = 9V, ILOAD = 700mA, VPINV = VPWR = 14V, Topside Switch = N-Ch
q 0.2 1
q 3.23 3.33 3.43 q 4.90 5.05 5.20
∆VOUT
IQ1 IQ2
Output Ripple (Burst Mode Operation)
Output Voltage Line Regulation
Output Voltage Load Regulation LTC1266-3.3 LTC1266-3.3 LTC1266-5 LTC1266-5
VIN Pin DC Supply Current (Note 3) Normal Mode Sleep Mode Shutdown
PWR VIN DC Supply Current (Note 3) Normal Mode Sleep Mode Shutdown
ILOAD = 150mA
ILOAD = 50mA VPINV = 0V, Topside Switch = P-Ch, VIN = 7V to 12V VPINV = VPWR.