LT1074 Linear Technology, LT1074 Datasheet
LT1074
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LT1074 Summary of contents
Page 1
... The switch output is specified to swing 40V below ground, allowing the LT1074 to drive a tapped- inductor in the buck mode with output currents up to 10A. The LT1074 uses a true analog multiplier in the feedback loop. This makes the device respond nearly instanta- neously to input voltage fluctuations and makes loop gain independent of input voltage ...
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... LT1074/ LT1076 .................................................. 45V LT1074HV/LT1076HV ......................................... 64V Switch Voltage with Respect to Input Voltage LT1074/ LT1076 .................................................. 64V LT1074HV/LT1076HV ......................................... 75V Switch Voltage with Respect to Ground Pin (V LT1074/LT1076 (Note 7) ..................................... 35V LT1074HV/LT1076HV (Note 7) ........................... 45V Feedback Pin Voltage ..................................... –2V, +10V Shutdown Pin Voltage (Not to Exceed V U PACKAGE/ORDER I FOR ATIO ...
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... C j > 125 through 2k (Note (Note 8) IN MAX 2V 2.5V REF = 2V C (Nominal) = 2.21V REF V (Note 8) IN MAX = 2.5V) SH THRESHOLD LT1074/LT1076 MIN TYP MAX UNITS 1.85 V 2.1 V 2.3 V 2.5 V 1 300 A 10 500 A 150 A 250 A 8 140 ...
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... MULTIPLIER – PULSE WIDTH Z COMPARATOR Y V 24V (EQUIVALENT – – 1k LIM LIM (LT1074) I (LT1076). LIM 2k 5.5k = 40V for the LT1074/76 and 60V for the LT1074HV/76HV. LT1074 500 CURRENT LIMIT 0.04 COMP + C2 250 – 400 15 SWITCH OUTPUT ( LT1076 0.1 100 ...
Page 5
... A current LIM source. When this pin is left open, it self-clamps at about 4.5V and sets current limit at 6.5A for the LT1074 and 2.6A for the LT1076. In the 7-pin package an external resistor can be connected from the I current limit. A capacitor in parallel with this resistor will soft-start the current limit ...
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... LT1074•PC05 Supply Current DEVICE NOT SWITCHING INPUT VOLTAGE (V) LT1074•TPC11 Feedback Pin Characteristics 500 400 300 200 START OF FREQUENCY SHIFTING 100 0 –100 –200 –300 –400 –500 ...
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... Error Amplifier Phase and 10k 100k 1M FREQUENCY (Hz) LT1074•TPC17 2.5 3.0 LT1074•TPC19 LT1074/LT1076 Switch “On” Voltage 3.0 2.5 2.0 LT1074 1.5 LT1076 1.0 0 SWITCH CURRENT (A) Switching Frequency vs Temperature 200 120 150 115 100 110 50 105 0 100 – –100 85 – ...
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... Figure 1. Input Capacitor Ripple L = Total inductance in input bypass connections P and capacitor. “Spike” height (dI/dt • approximately 2V per P inch of lead length for LT1074 and 0.8V per inch for LT1076. “Step” for ESR = 0.05 and I SW “Ramp” for C = 200 and 0.12V. ...
Page 9
... Switching frequency 100kHz, t must drop to 0.2 s when V ON and the output is shorted (V = 0V). In current limit, OUT the LT1074 can reduce minimum value of ON 0.6 s, much too long to control current correctly for correct this problem, switching frequency OUT is lowered from 100kHz to 20kHz as the FB pin drops from 1 ...
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... Example: An undervoltage lockout is required such that the output will not start until V to operate until GND LT1074•PD08 LIM SHUT LT1074 D1 LIM R2 OPTIONAL CURRENT LIMIT RESISTOR *1N4148 LT1074•PD09 Figure 7. Adding Hysteresis R 1 int ...
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... LIM LIM (5. (LT1076) LIM LIM As an example current limit would require 3A(2k for the LT1074. The accuracy of these formulas is 25% for 2A I LIM 7A I 1.8A (LT1076 LIM LIM 25% above the peak switch current required. Foldback current limiting can be easily implemented by adding a resistor from the output to the I in Figure 9 ...
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... Low clamp voltage is approximately one diode drop ( 0.7V – 2mV/ C). variations, O Note that both the FB pin and the V , which is m connections. Refer to the frequency shifting and synchro- nizing discussions. and 5. EXTERNAL FREQUENCY COMPENSATION LT1074 • PD11 pin have other internal C ...
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... VOLTAGE OF 4.5V. HIGHER MINIMUM INPUT VOLTAGE WILL ALLOW MUCH HIGHER OUTPUT CURRENTS. SEE AN44. LT1074/LT1076 OUT † 5V, 10A R1 2. 4400 2200 16V) 390 F 2.21k 16V LT1074 •TA02 R3* 2.74k + C2 1000 F 10V OPTIONAL FILTER – 200 F R4 10V + 1.82k* –5V,1A*** LT1074 • TA03 13 ...
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... LT1074/LT1076 PACKAGE DESCRIPTIO 0.320 – 0.350 0.420 – 0.480 (10.67 – 12.19) 0.060 0.256 (1.524) (6.502) 0.060 0.183 (1.524) (4.648) 0.075 (1.905) 0.300 (7.620) BOTTOM VIEW OF DD PAK HATCHED AREA IS SOLDER PLATED COPPER HEAT SINK 14 U Dimensions in inches (millimeters) unless otherwise noted. K Package ...
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... SEATING PLANE 0.152 – 0.202 (3.861 – 5.131) 0.260 – 0.320 (6.60 – 8.13) 0.135 – 0.165 (3.429 – 4.191) LT1074/LT1076 0.165 – 0.180 0.045 – 0.055 (4.191 – 4.572) (1.143 – 1.397) 15 TYP +0.008 0.004 –0.004 ...
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... R1 12.7k R2 2.21k + C1 1000 F 25V V OUT –15V** + 100 F LT1074 • TA04 0.045 – 0.055 (1.143 – 1.397) 0.620 (15.75) TYP 0.095 – 0.115 (2.413 – 2.921) 0.155 – 0.195* (3.937 – 4.953) 0.013 – 0.023 (0.330 – 0.584) *MEASURED AT THE SEATING PLANE T7 (TO-220) 0399 ...