LTC1266 Linear Technology, LTC1266 Datasheet
LTC1266
Available stocks
Related parts for LTC1266
LTC1266 Summary of contents
Page 1
... Q (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 Burst Mode operation are typically 0mA to 500mA ...
Page 2
... Storage Temperature Range ................ – 150 C Lead Temperature (Soldering, 10 sec)................. 300 C ELECTRICAL C HARA TERISTICS C SYMBOL PARAMETER V Feedback Voltage FB LTC1266ACS LTC1266CS I Feedback Current (LTC1266 Only Regulated Output Voltage OUT LTC1266CS-3.3 LTC1266CS-5 Output Ripple (Burst Mode Operation Output Voltage Line Regulation OUT Output Voltage Load Regulation LTC1266-3 ...
Page 3
... Max Sink Current into Pin 14 LBSINK I Max Leakage Current into Pin 13 LBIN – < T < (Note 4 10V, unless otherwise noted SYMBOL PARAMETER V Feedback Voltage (LTC1266 only Regulated Output Voltage OUT LTC1266-3.3 LTC1266 Pin DC Supply Current (Note ...
Page 4
... Note 4: The LTC1266, LTC1266-3.3, and LTC1266-5 are not tested and A not quality assurance sampled at – and 85 C. These specifications are guaranteed by design and/or correlation. Note 5: Unless otherwise noted the specifications for the LTC1266A are the same as those for the LTC1266. C HARA TERISTICS ...
Page 5
... Efficiency vs Input Voltage 100 FIGURE 11 CIRCUIT LOAD I = 2.5A LOAD 100mA 85 LOAD INPUT VOLTAGE (V) LTC1266 • TPC04 V DC Supply Current IN 3.0 2.5 ACTIVE MODE 2.0 1.5 1.0 0.5 SLEEP MODE INPUT VOLTAGE (V) LTC1266 • TPC07 Off-Time vs Output Voltage 100 – V ...
Page 6
... TH comparator threshold increases with the Pin 7 voltage. – Sense (Pin 8): Connects to internal resistive divider which sets the output voltage in LTC1266-3.3 and LTC1266-5 versions. Pin 8 is also the (–) input for the current comparator Sense (Pin 9): The (+) Input to the Current Comparator. A built-in offset between Pins 8 and 9 in conjunction with R sets the current trip threshold ...
Page 7
... The voltage comparator is the primary control element when the device is in Burst Mode operation, while the gain block controls the output voltage in continuous mode. W Pin 10 Connection Shown for LTC1266-3.3 and LTC1266-5; Changes Create LTC1266 14 LB – LB ...
Page 8
... The Burst Mode operation inhibit (BINH, Pin 4) allows the Burst Mode operation to be disabled by applying a CMOS logic high to this pin. With Burst Mode operation disabled, the LTC1266 will remain in continuous mode down to zero load. Burst Mode operation is disabled by allowing the lower current threshold limit to go below zero so that the voltage comparator will never trip ...
Page 9
... Since efficiency generally increases with ripple current, the maximum allowable ripple current is assumed, i.e 25mV/R (see C RIPPLE(P-P) SENSE Operating Frequency). Solving for R a margin for variations in the LTC1266 series and external component values yields: = 100mV R SENSE I MAX A graph for selecting R vs maximum output SENSE current is given in Figure 2 ...
Page 10
... L T Power MOSFET and D1 Selection SENSE Two external power MOSFETs must be selected for use with the LTC1266 series: either a P-channel MOSFET or an N-channel MOSFET for the main switch and an N-channel V T REG MOSFET for the synchronous switch. The main selection ...
Page 11
... This causes 1/2 (V – OUT Burst Mode operation to be activated when the LTC1266 V IN LTC1266 LTC1266-3.3/LTC1266 /2. This simple worst-case condition is com- is driven by the required ESR. The ...
Page 12
... This minimum capacitance requirement may be relaxed if Burst Mode operation is disabled. N-Channel vs P-Channel MOSFETs The LTC1266 has the capability to drive either an N-channel or a P-channel topside switch to give the user more flexibility. N-channel MOSFETs are superior in per- formance to P-channel due to their lower R lower gate capacitance and are typically less expensive ...
Page 13
... I series resistance of C LTC1266 LTC1266-3.3/LTC1266-5 100 Burst Mode OPERATION ENABLED 90 80 Burst Mode OPERATION INHIBITED 70 60 0.01 0 LOAD CURRENT (A) LTC1266 • F07 MIN shifts by an OUT (ESR), where ESR is the effective LOAD . I also begins to charge or OUT LOAD ) specified 13 ...
Page 14
... LTC1266 DC supply IN IN current is 170 A for no load, and increases proportion- ally with load constant 2.1mA after the LTC1266 series has entered continuous mode. Because the DC bias current is drawn from V increases with input voltage. For V losses are generally less than 1% for load currents over 30mA ...
Page 15
... Figure 11circuit. If this isn’t for each MOSFET true (as with the Figure 1 circuit) the R which in turn increases V Adjustable Applications = 0.076 When an output voltage other than 3. required, the LTC1266 adjustable version is used with an external = 0.147 resistive divider from V voltage is determined by about 0.04 at ...
Page 16
... I ) Burst Mode BURST 1. Are the signal and power grounds segregated? The pin waveform periodi- LTC1266 signal ground (Pin 12) must return to the (–) plate of C source of the bottom-side MOSFET, anode of the 3.3V Schottky diode and (–) plate of C have as short lead lengths as possible. ...
Page 17
... LB IN LTC1266-3 SGND SHDN SHUTDOWN – + SENSE SENSE 1000pF LTC1266 LTC1266-3.3/LTC1266 3.9V TO 18V ( < 0.8A) IN(MIN) LOAD + C IN 100 F 25V D1 MBRS140T3 OUT 220 F 10V + 2 R SENSE 0.033 V OUT 3.3V 3A LTC1266 • F11 17 ...
Page 18
... 3300pF – + SENSE SENSE C 1000pF D1 MBRS130LT3 V OUT 12V/500mA 118k + 1% C 0UT Si9410DY 100 F 20V 13.7k 100pF 1% 1N4148 SHUTDOWN LTC1266 • F12 PWR V – < 2.5A) IN(MIN) LOAD 100 F 20V D1 2 MBRS140T3 L* C OUT 5 H 220 F 10V + 2 R SENSE ...
Page 19
... LTC1266 LTC1266-3.3/LTC1266 10V OS-CON 3 D1 MBRS340T3 L* C OUT 5 H 330 F 10V + 3 R SENSE 0.01 V OUT 3.3V 10A LTC1266 • F14 3. < 1A) IN(MIN) LOAD 100 F + 10V OS-CON 2 D1 MBRS130T3 L* 100k 100pF OUT 330 F 10V + 2 ...
Page 20
... LTC1266 LTC1266-3.3/LTC1266-5 PACKAGE DESCRIPTION 0.010 – 0.020 45 (0.254 – 0.508) 0.008 – 0.010 0 – 8 TYP (0.203 – 0.254) 0.016 – 0.050 0.406 – 1.270 * DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" ...