ltc1147l Linear Technology Corporation, ltc1147l Datasheet
ltc1147l
Available stocks
Related parts for ltc1147l
ltc1147l Summary of contents
Page 1
... For applications where even higher efficiency is required, refer to the LTC1148 data sheet and Application Note 54. , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation. *LTC1147L and LTC1147L-3.3 only 100 F ...
Page 2
... T = 125 C, = 150 C/W (S) JMAX JA Consult factory for Military grade parts. ELECTRICAL CHARACTERISTICS SYMBOL PARAMETER V Feedback Voltage (LTC1147L Feedback Current (LTC1147L Regulated Output Voltage OUT LTC1147-3.3, LTC1147L-3.3 LTC1147-5 V Output Voltage Line Regulation OUT Output Voltage Load Regulation LTC1147-3.3, LTC1147L-3.3 LTC1147-5 Burst Mode Output Ripple ...
Page 3
... C and 85 C. The D LTC1147I is guaranteed to meet the extended temperature limits )(150 C/W) Note 5: The LTC1147L/LTC1147L-3.3 allow operation Note 6: The LTC1147L is tested with external feedback resistors resulting in a nominal output voltage of 2.5V. LTC1147-3.3 LTC1147-5/LTC1147L = 0V, unless otherwise noted. SHDN MIN ...
Page 4
... LTC1147 • G07 4 Line Regulation 40 FIGURE 1 CIRCUIT LOAD –10 –20 –30 – INPUT VOLTAGE (V) Supply Current in Shutdown SHUTDOWN 18 (NOT AVAILABLE ON LTC1147L INPUT VOLTAGE (V) Off-Time vs V OUT 80 V SENSE 70 60 ...
Page 5
... Pin 6 high holds the P-channel MOSFET off and puts the LTC1147 in micropower shutdown mode. Requires CMOS logic signal with t On the LTC1147L this pin serves as the feedback pin from an external resistive divider used to set the output voltage. GND (Pin 7): Two independent ground lines must be routed separately to: 1) the (– ...
Page 6
... This causes the output of the gain stage APPLICATIO S I FOR ATIO U U LTC1147L Adjustable Applications When an output voltage other than 3. required, the LTC1147L adjustable version is used with an external resistive divider from (Pin 6) (see Figure 7). OUT FB The regulated voltage is determined by: ...
Page 7
... T (1.3)(10 Where V has been chosen graph for selecting C effects of input voltage is given in Figure 3. As the operating frequency is increased the gate charge losses will reduce efficiency (see Efficiency Consider- ations). The complete expression for operating frequency LTC1147-3.3 LTC1147-5/LTC1147L 0.20 0.15 0.10 0. MAXIMUM OUTPUT CURRENT (A) LTC1147 • ...
Page 8
... LTC1147-3.3 LTC1147-5/LTC1147L APPLICATIO S I FOR ATIO U U 1000 SENSE – V 800 600 400 V = 12V IN 200 200 100 FREQUENCY (kHz) Figure 3. Timing Capacitor Value is given by OUT f 1 – OFF IN where: V REG (1.3)(10 )(C ) OFF T V OUT V is the desired output voltage (i.e., 5V, 3.3V). V REG the measured output voltage ...
Page 9
... Always consult the manufacturer if there is any question. An additional 0 ceramic decoupling capacitor is also required on V high frequency decoupling. The selection of C series resistance (ESR). The ESR of C than twice the value of R LTC1147: C OUT LTC1147-3.3 LTC1147-5/LTC1147L (V – OUT LOAD ...
Page 10
... LTC1147-3.3 LTC1147-5/LTC1147L APPLICATIO S I FOR ATIO U U Optimum efficiency is obtained by making the ESR equal the ESR is increased SENSE efficiency degrades by less than 1%. If the ESR is greater than 2R , the voltage ripple on the output capacitor SENSE will prematurely trigger Burst Mode operation, resulting in disruption of continuous mode and an efficiency hit which can be several percent ...
Page 11
... The GATECHG P reduced. As expected, the I P-channel power diode loss dominate at high load currents. = 4mA in GATECHG LTC1147-3.3 LTC1147-5/LTC1147L to obtain I SENSE = 0 DS(ON) = 0.05 , then the total resistance is 0.3 SENSE 2V . This results in losses ranging from 3% OUT R losses cause the efficiency to roll off at high ...
Page 12
... LTC1147-3.3 LTC1147-5/LTC1147L APPLICATIO S I FOR ATIO U U Other losses including C and C IN losses, MOSFET switching losses, and inductor core losses, generally account for less than 2% total additional loss. Design Example As a design example, assume (nominal 3.3V 1A, and f = 130kHz; R ...
Page 13
... SHDN – SENSE SENSE SHUTDOWN 1000pF For additional High Efficiency application circuits see Application Note 54. LTC1147-3.3 LTC1147-5/LTC1147L – + and SENSE leads routed together with connect to the source of the IN (Pin 1) and ground (Pin 7 SENSE + + ...
Page 14
... SHDN 300pF 3300pF + – SENSE SENSE 0. SUMIDA CDR74-221 ** IRC LRC-LR2010-01-R068-F 14 3.3V Low Dropout High Efficiency Regulator 0.1 F LTC1147L-3.3 8 PDRIVE GND SHDN SHUTDOWN – SENSE SENSE 0. 10V TO 14V + Si3455DV D1 MBRS130LT3 L* 220 ...
Page 15
... Dimensions in inches (millimeters) unless otherwise noted. N8 Package 8-Lead PDIP (Narrow 0.300) (LTC DWG # 05-08-1510) 0.130 0.005 0.045 – 0.065 (3.302 0.127) (1.143 – 1.651) 0.125 (3.175) MIN 0.018 0.003 (0.457 0.076) LTC1147-3.3 LTC1147-5/LTC1147L V IN 3.5V TO 12V + Si9433DY D1 25V 2 MBRD330 ...
Page 16
... LTC1147-3.3 LTC1147-5/LTC1147L TYPICAL APPLICATION 220pF 3300pF COILTRONICS CTX20-4 ** KRL SP-1/2-A1-OR050 PACKAGE DESCRIPTIO 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" ...