Features

The input voltage range is wide: 3V to 60V

Low static current: 6MA

Internal 5A switch (LT1171 is 2.5A, LT1172 is 1.25 to 1.25 A)

The shutdown mode only consumes 50 μA power current

Rarely requires external parts

overload self -protection

Working in almost all switching topology [ 123]

Anti -excitement mode has a full floating output

standard 5 -needle packaging

LT1172 provides 8 -needle micro -mini DIP and surface installation

] Can be synchronized with external

Application

Logic power supply 5V, 10A

5V logic to ± 15V operation amplifier power supply

Battery upper inverter [ 123]

Power inverter (+to-) or (-to+)

Full floating output

Instructions

lt #174; 1170/LT1171 /LT1172 is a single -piece high -power switch regulator. They can switch configurations according to all standard operations include buck, boost, Flyback, positive, inverter and ""CUK"". A high current, high -efficiency switch, together with all oscillators, control and protect the circuit. Combining all functions allows 5-pin To-3 or TO-220 power packs and 8-stick packaging (LT1172) of the 5-pin TO-3 or To-220 (LT1172) of the built-in LT1170/LT1171/LT1172 standard (LT1172). This makes them easy to use and provide a similar ""anti -chest"" operation 3 needle linear stabilizer. LT1170/LT1171/LT1172 works under the power supply voltage of 3V to 60V, and only 6mA current is consumed during static. They can provide up to 100W load power without external power equipment. By using the current mode switching technology, they provide excellent communication and DC load and line adjustment. LT1170/LT1171/LT1172 has many unique features even available even more difficult to use low power control chips. They use adaptive scratch -resistant switch drivers to allow very wide load currents without loss efficiency. External activation shutdown mode reduces the total power supply to 50 μA for spare operation.

absolute axis ratio (NOTE 1)

Power voltage

Note 7271 (LT722/1172) 60 volt

lt1170/71/72 (Note 2 2 ) 40 volts

Switch output voltage

LT1170/71/72HV75 volt

LT1170/71/72 65 volt

LT117278 60 il

Storage temperature range –65 ° C to 150 ° C

Lead temperature (welding, 10 seconds) 300 degrees Celsius

Working temperature range

LT1170 /71/72-55 ° C to 150 ° C

LT1170/71/72HVC,

LT1170/71/72C (operation) 0 ° C to 100 ° C

] LT1170/71/72HVC

LT1170/71/72C (shell) 0 ° C to 125 ° C

LT1170/71/72HVi,

LT1170/71/72i (Operation) – 40 ° C to 100 ° C

LT1170/71/72HVI,

LT1170/71/72i (shell) –40 ° C to 125 ° C

] The electrical characteristics indicate the specifications suitable for the entire working temperature range, otherwise the specifications are TA u003d 25 ° C. VIN u003d 15V, VC u003d 0.5V, vfb u003d vREF, output pins, unless there is another explanation.

Note 1: The absolute maximum rated value means that the value of exceeding life may damage the device.

Note 2: LT1170/71/72 (current) minimum effective switch ""open"" time is only ≈0.6μs. This limits short -circuits in the output. The short -circuit conditions of the input voltage output voltage of the antihypertensive mode and the inverter mode are limited to:

R u003d DC resistance of the inductor

For LT1170, IL u003d 10A; LT1172, IL u003d 2.5A

The output capture diode positive voltage when the output capture diode

t u003d 0.6μs, F u003d 100kHz switch frequency

The maximum input voltage can pass through Increase R or VF to increase. External current restrictions, as shown in FIG. 39 of AN19, will provide the protection of the rated voltage of high full power supply. The C1 in Figure 39 should be reduced to 200pf.

The transformer design will withstand higher input voltage, because the leakage limits the rise rate of the current in the switch. These designs must be evaluated separately to ensure good current restrictionsGood control to the maximum input voltage. The design of the booster mode will never be protected by short -circuited output, because the input and output of the diode and the inductors are captured outside.

Note 3: Use VC measurement in Hi fixture, VFB u003d 0.8V. LT1170's isw u003d 4A, LT1171 is 2A, and LT1172 is 1A.

Note 4: When the duty cycle (DC) is between 50%and 80%, the guarantee switch current with the minimum value of LT1170 is given by ILIM u003d 3.33 (2 -DC). For LT1171, ILIM u003d Ilim u003d 1.67 (2 -DC), for LT1171, Ilim u003d 0.833 (2 – DC) LT1172.

Note 5: The minimum input voltage of the isolation anti -gratifying mode is 7V.VMAX u003d in a complete isolation mode, the high voltage level is 55V to avoid switching through.

典型性能特征

[123 ] Be sure to connect E1 to MINIDIP, 8 stitches, and 16 -needle surface to install the ground needle foot. E1 and E2 are enclosed in the to-3 and TO-220 internal ground.

Operation

LT1170/LT1171/LT1172 is a current mode switch. This means that the occupation ratio switch directly controls the switch current instead of the output voltage. Refers to in the box diagram, the switch is in each oscillator cycle. When switching current, it is closed to the predetermined level. The output voltage control obtains a amplifier that sets the position of the market through the output of the voltage induction error. There are several advantages of this technology. First of all, it is different in the input voltage changes. It is different from the ordinary switch. Second, it reduces energy storage sensors. This greatly simplifies the closed -loop frequency compensation voltage or output load conditions under a large range of input. Finally, it allows simply providing the maximum switch -by -pulse current limit output overload or short circuit protection. A2.3V internal antihypertensive power supply LT1170/LT1171/LT1172. This low -voltage difference design allows input voltage from 3V to 60V, and the equipment performance has almost no change. A100KHz oscillator is the basic clock of all internal timing. It opens the output switch circuit through logic and drive. Special adaptive anti -satellite circuit detection of the disease at the power switch and adjust the driver saturated instantaneous current limit switch saturation. This reduces the driver's loss to the maximum extent and provides the function of quickly shut down the switch. 1.2V gap benchmark will make an error amplifier. The negative input is the output voltage induction. This feedback tube foot has a function; when the external resistor is pulled down, the program is programmed LT1170/LT1171/LT1172Connect the anti -tights to the comparator input terminal. LT1170/LT1171/LT1172 will regulate the pulse related to the power supply voltage. *This anti -trap and output voltage is proportional to the traditional transformer coupling coupled anti -fierce topology regulator. By adjusting the amplitude output voltage of the anti -trap pulse, there is no need to be directly connected between the input and output. The output completely floats to the breakdown voltage of the transformer winding. Multiple floating outputs can easily get extra winding. LT1170's internal special latency network/LT1171/LT1172 ignored the cutting -edge of the anti -trammal pulse and increased the output regulations.

The error signal generated by the comparator input end is brought out of the outside. This pin (VC) has four different functions. Used for frequency compensation, current limit adjustment, soft startup and total regulator shutdown. During the operation of the normal regulator, the output current was sold at 0.9V (low output current) and 2.0V (high)). The error amplifier is the current output (GM) type, so this voltage can be adjusted by external restrictions. Similarly, the capacitor coupling external clamping will provide soft start. The switching ratio of the switch is placed in the idle mode of LT1170/LT1171/LT1172 through the diode. Pulling the VC pin below 0.15V will cause the entire regulator to stop, and the current source current is only 50 μA circuit bias. For a complete application of a complete application, see AN19.

The 8 -needle and 16 -needle version of the 8 -needle and 16 -needle version of the minidip and surface installation of the packaging of the power transistor have the ground pins of the power transistor, respectively. This eliminates the decrease of error pins caused by grounding, allowing users to reduce the connection of the switching volume by disconnecting the second transmitter (E2), and the current limit is 2: 1. The first transmitter (E1) should always be connected to the ground. Note that when the switch ""ON"" resistance is counted, when the E2 is opened, the efficiency will be affected to a certain extent that when the switch current exceeds 300mA. In addition, pay attention to the operation of the chip in normal load, even if the current dispersing restriction mode will be reduced. See the next one. The use of Minidip and software package power currents is small, and the switching efficiency is high. LT1172 allows applications to select TO-220 or to-3 software packages without using a radiator in most cases. The rated temperature of these packaging is 50 ° C/W and 35 ° C/W, respectively. However, the rated temperature of Minidips is 100 ° C/W ceramic (J) and plastic (N) 130 ° C/W. Pay attention to the Minidip application to ensure that the input voltage and load current conditions will not cause the mold temperature to be too high in the worst case. The following formulas can be used as a rough calculation guide LT1172 power consumption. For more details, readers reference to application comments 19 (An19), ""efficiency calculation"" section. The average power supply current (including the driver current) is: IIN≈6MA+ISW (0.004+DC/40)

ISW u003dSwitch current

dc u003d switch occupation ratio

The power consumption of the switch is obtained from the following formulas:

psw u003d (ISW) 2 (RSW) (DC)

RSW u003d LT1172 switch ""connect"" resistance (maximum 1 #8486;)

The total power consumption is the total power current time and the input voltage plus switching power supply:

pd (tot) u003d (IIN) (vehicle recognition number)+PSW In a typical example, use Boost converter to generate 12V, 0.12A, 5V input, the duty cycle is about

60%, the switching current is about 0.65 A, generate:

iin u003d 6ma+0.65 (0.004+dc/40) u003d 18ma

psw u003d (0.65) 2 (1 #8486;) (0.6) u003d 0.25W [123 [123) ]

PD (TOT) u003d (5V) (0.018A)+0.25 u003d 0.34W

The temperature in the plastic microlithic fluid is 130 ° C/W, multiply at 0.34W, or about 44 ° C. The maximum room temperature will be limited at 100 ° C (commercial temperature limit) to -44 ° C or 56 ° C. In most applications, the mold temperature calculated with a full -load current. However, if the overload conditions must be separated, there are four possible methods. First, if the loss of adjustment output can be accepted under overload conditions, the internal thermal limit of the LT1172 will be protected by closing the switch in most applications. However, the heat limit is not a test parameter, only non -critical applications should be temporarily overloaded. The second method is to use larger to-220 (t) or to-3 (k) packaging. Even if there is no heat sink, the mold temperature may be limited to overload. In emergency situations, these packaging is necessary; especially when the overload must be endured for a long time. The third method of low -current applications is to keep the second switch transmitter (only MINIDIP) open. This switch ""open"" resistance increases by 2: 1, but the reduction of the switching current limit is also 2: 1, resulting in the net current to reduce the I2R switch loss condition under 2: 1 current limit. The fourth method is to clamp the VC's foot in a low voltage position. The internal clamp level is 2V. When the LT1172 switch is about 1V, the current on the VC pin is limited to zero, and the 2V voltage on the VC pin is 2A. The peak switch current can be clamped outside the diode between these two levels. See AN19 for details.

LT1170/LT1171/LT1172 synchronization

LT1170/LT1171/LT1172 can perform external synchronization within the frequency range of 120kHz to 160kHz. This is as shown in the attached figure. When the VC pin is pulled to the groundThere is an external transistor in synchronization. To avoid interference with the characteristics of the internal error amplifier of the DC power, the synchronization pulse should be less than 0.3 μs. The pulse width of the C2 group at #8773; 0.2 μs. Synchronous effect LT1170/LT1171/LT1172 amplifier offset the pulse calculation formula on CAN:

ts u003d pulse width

fs u003d pulse frequency

[

[

[

[

[

[

123] IC u003d VC source current (≈200 μA)

VC u003d operating voltage (1V to 2V)

R3 u003d The frequency compensation network for setting the intermediate frequency ""zero"" resistor.

TS u003d 0.2 μs, FS u003d 150kHz, VC u003d 1.5V, R3 u003d 2K, and the offset voltage drift ≈3.8MV. This is not particularly troublesome, but please note that if R3 is reduced to a very low value. At the same time, the leakage current R3 of the synchronous transistor must be higher, so a larger driver may be used. The transistor must be able to pull the VC pins to the 200mv out of the ground to ensure synchronization.

d2, d3 u003d ER82.004 600ma Shawki. You can use other fast switching types. Vehicle identification number (VIN) and battery may be connected. The maximum value of VBAT is equal to #63718; negative output #63718;+1V battery voltage. Runing the LT1172 VIN pin from 5V to get the highest efficiency. Closing the 5V power supply will automatically turn off the LT1172. When iOut u003d 25mA, the efficiency is about 80%. R1, R2, and R3 become larger to minimize the battery consumption at the time of shutdown, about VBAT/(R1+R2+R3). In order to improve the efficiency, L1 should be made on iron or molybdenum alloy magnetic cores. The output voltage of the peak inductor current is 600 mAh u003d 0.7 #8486;. The inductor series resistance should be less than 0.4 #8486; to improve efficiency. In the case of C2 u003d 2 μF 情况, the output ripples are about 200mvp-P to 400mvp-P. If you need lower ripples, increase C2, or increase 10 #8486; 1 μF 钽 output filter.

典型应用（注意，LT1171的最大输出电流除以2，LT1172的最大输出电流除以4。）

[123 ]