LT1111 LINER [Linear Technology], LT1111 Datasheet
LT1111
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LT1111 Summary of contents
Page 1
... The device requires only three external components to deliver a fixed output 12V. Supply voltage ranges from 2V to 12V in step-up mode and to 30V in step-down mode. The LT1111 functions equally well in step-up, step- down, or inverting applications. The LT1111 oscillator is set at 72kHz, optimizing the device to work with off-the-shelf surface mount inductors ...
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... V Gain Block Output Low Operating Temperature Range LT1111C ............................................... LT1111I ......................................... – 105 C IN LT1111M ....................................... – 125 C Storage Temperature Range ................ – 150 C Lead Temperature (Soldering, 10 sec)................. 300 ORDER PART NUMBER I 1 LIM LT1111CN8 ...
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... – 400 – 350 mV LT1111M MIN TYP MAX UNITS 300 500 100 kHz 0.2 0.4 %/V 0.8 %/V 0.5 0.65 V 1.5 V 2.0 V LT1111C MIN TYP MAX UNITS 300 450 5.0 7 9.0 s 3.3 5 7.8 s 0.2 0.7 %/V 0.5 0.65 V 1.1 1. ...
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... IN 0.9 I 650mA SW = 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 –50 – 100 TEMPERATURE ( C) LT1111 • TPC05 Switch ON Voltage Step-Down Mode 1 12V IN 1.2 1.0 0.8 0.6 0.4 0 0.2 0.4 0.6 0.8 SWITCH CURRENT (A) LT1111 • TPC08 Switch ON Time 10 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 –50 – TEMPERATURE ( C) Saturation Voltage Step-Up Mode 1.4 1 1.0 0.8 0.6 0.4 0.2 0 125 0 0.2 0.4 0.6 0.8 1.0 1.2 SWITCH CURRENT (A) Minimum/Maximum Frequency ...
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... SET pin and negative input connected to 1.25V reference. FB/SENSE (Pin 8): On the LT1111 (adjustable) this pin goes to the comparator input. On the LT1111-5 and LT1111-12, this pin goes to the internal application resistor that sets output voltage. Maximum Switch Current vs R LIM 1 ...
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... The LT1111-5 and LT1111-12 are functionally identical to and V OUT IN the LT1111. The -5 and -12 versions have on-chip voltage setting resistors for fixed 5V or 12V outputs. Pin 8 on the fixed versions should be connected to the output. No external resistors are needed. LT1111-5/LT1111-12 ...
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... The inductance must also be high enough so maxi- mum current ratings of the LT1111 and inductor are not exceeded at the other worst case condition of maximum input voltage and ON time. Additionally, the inductor core must be able to store the required flux ...
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LT11 PPLICATI S I FOR ATIO Picking an inductor value with 0.2 DCR results in a peak switch current of: – ...
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... Corporation (San Diego, CA). These units are physically ( ) 15 quite small and have extremely low ESR. To illustrate, Figures 1, 2, and 3 show the output voltage of an LT1111 based converter with three 100 F capacitors. The peak switch current is 500mA in all cases. Figure 1 shows a Sprague 501D, 25V aluminum capacitor. V over 120mV when the switch turns off, followed by a drop in voltage as the inductor dumps into the capacitor ...
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... V at the internal reference voltage of 1.25V. R1 and FB R2 set the output voltage according to the formula V OUT Step-Down (Buck Mode) Operation A step-down DC/DC converter converts a higher voltage to a lower voltage. The usual hookup for an LT1111 based step-down converter is shown in Figure – IN ...
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... D1 turns on when SW2 reaches 0.4V below ground. D1 MUST BE A SCHOTTKY DIODE . The voltage at SW2 must never be allowed to go below –0.5V. A silicon diode such as the 1N4933 will allow SW2 –0.8V, causing potentially destructive power dissipation inside the LT1111. Output voltage is deter- mined by ...
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... Figure 8. Negative-to-Positive Converter Using the I Pin LIM The LT1111 switch can be programmed to turn off at a set switch current, a feature not found on competing devices. This enables the input to vary over a wide range without exceeding the maximum switch rating or saturating the inductor. Consider the case wh ...
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... S I FOR ATIO Using the Gain Block The gain block (GB) on the LT1111 can be used as an error amplifier, low-battery detector or linear post regulator. The gain block itself is a very simple PNP input op amp with an open collector NPN output. The negative input of the gain block is tied internally to the 1 ...
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... AT 6.5V INPUT 22 F LT1111 • TA04 732k 1% 0.1 F 39. 220k –22V OUTPUT 7mA AT 2V INPUT LT1111 • TA03 20V to 5V Step-Down Converter V IN 100 I V LIM IN SW1 LT1111-5 SENSE GND SW2 L1 OUTPUT 300mA + 47 F MBRS130T3 * L1 = SUMIDA CD74-680M LT1111 • TA06 ...
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... MTM20P08 BAT54 2k 51 2N3904 SW1 1N4148 FB 40. SUMIDA CDR105-100M –5V OUTPUT 75mA LT1111 • TA05 L1 MBRD320 –V = –5.13 V OUT C 2W MAXIMUM OUTPUT 39k V (0V TO 5V) C LT1111 • TA07 L1 500mA + MBRD320 220 F 121k LT1111 • TA20 LT1111 15 ...
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LT11 11 PACKAGE DESCRIPTIO CORNER LEADS OPTION (4 PLCS) 0.290 – 0.320 (7.366 – 8.128) 0.023 – 0.045 (0.584 – 1.143) HALF LEAD OPTION 0.045 – 0.068 (1.143 – 1.727) 0.008 – 0.018 FULL LEAD 0° – 15° (0.203 – ...