Features

Constant 200kHz switch frequency

1.21V reference voltage

fixed 5V output option

Easy synchronization

Battery charger

distributed power supply

Description

LT #174; Series 1576 is 200kHz single -chip antihypertensive mode switch regulator. The mold includes all the necessary oscillators, control and logical circuits on the 1.5A switch. This topology is a good circuit stability with a good current mode of fast transient response. LT1576 is an optimized application of the industrial standard LT1376. In addition, the reference voltage has been reduced to the output voltage of as low as 1.2V that allows the device to generate as low as 1.2V. Static current decreases by double. The connection resistance was reduced by 30%. The switch conversion time has slowed to reduce the generation of electromagnetic interference. The frequency of oscillator is reduced to 200kHz in a wide output current range. Put your footsteps to improve the PC layout so that the high -current high -frequency switch circuit is easy to isolate the control circuit from the low -current noise sensitive circuit. The new SO-8 component, including a fuse, has a significantly reduced thermal resistance of the device, thereby extending the temperature range of the environment. There is an optional shutdown function or synchronization. External parts installed on the standard surface can be used to include inductance and capacitors.

Absolutely maximum rated value (Note 1)

Input voltage 25 volts

The increased voltage pins are higher than the input voltage 10 volt

SHDN pin pressure 7 volts

Partial pressure pins 7 volts

FB pins voltage (adjustable part) 3.5 volts

FB pins current (adjustable part) 1 millhhhhhhhhhhhhhhhhhhhh

Synchronous pins voltage 7 volts

The temperature range of the work knot

LT1576C0 ° C to 125 ° C

LT1576i –40 ° C to 125 ° C

Storage temperature range –65 ° C to 150 ° C

Lead temperature (welding, 10 seconds) 300 degrees Celsius

Electric characteristics indicate to the specification range of the entire work temperature. OtherwiseFor TA, TJ 25 ° C, vin 15V, VC 1.5V, boost vin+5V, the switch is turned on unless there is another explanation.

The electrical characteristics indicate the scope of the entire working temperature, otherwise the specifications are TA, TJ 25 ° C, vin 15V, VC 1.5V, boost vin vin +5V, the switch is turned on unless there is another explanation.

Note 1: The absolute maximum rated value means that the life span exceeds that the device may be damaged.

Note 2: The gain is 200MV with the VC switching to the level below the top of the top.

Note 3: The minimum input voltage does not measure directly, but it is guaranteed to pass other tests. It is defined as an internal bias line that still exists to keep the reference voltage and the frequency of oscillator unchanged. The actual minimum input voltage that maintains stable output depends on the output voltage and load current. See application information.

Note 4: This is to ensure that the internal power switch needs to be completely saturated through the minimum voltage required by the voltage capacitor.

Note 5: Boost Current means that the current that flows into the pyramid pipe foot through the foot of the pipe is kept higher than the input voltage 5 volt. It only flows within the connection time.

Note 6: VIN's power current is that the current when the current keeps the pressure pins is disabled when the current is 5V. The total input reference power current is calculated to calculate the power supply current (ISB) ITOT ISI+(ISB) (VBIAS/VIN) (1.15) by the input power supply current (ISI). Identification number 5V, ISI 0.55mA, ISB 1.6ma, when itot 1.16ma. If the bias pipe foot is not available or opens, the total power current of the vehicle recognition number and bias will be led by the vehicle identification number pins.

Note 7: The vehicle identification number (VIN) is divided by vehicle voltage (VSW) to calculate the connection resistance through the mandatory current (1.5A). See the typical performance characteristics of the switch voltage diagram under other current.

Note 8: Cross -guidance and voltage gain refers to the internal amplifier does not include a separator. In order to calculate the gain and cross -guidance, please refer to the detection and sales on the fixed voltage component. Except for the display value VOUT/1.21.

Note 9: Slipping compensation is the current limit when the current minusing the current minus to the current is 80%. See the largest output load current application information part to learn more about more details.

Note 10: The typical minimum opening time is 400ns. For 200kHz, the running frequency means that the minimum duty cycle is 8%. The frequency folding mode, the effective occupation ratio is less than 8%.

Typical performance features

vsw (pin 1): The switch pins are the power supply of the launcher on the film NPN switch. The pins are driven to the voltage during the input pin. During the shutdown of the inductor current, the pin is switched to negative poles. The negative voltage captures the diode with external capture. The negative switch voltage allowed to the maximum value is -0.8V.

VIN (pin 2): This is the collector switching of the power NPN on the film. This pin is a regulator when the internal circuit and internal bias are sold. Open and off at the NPN switch, the edge of the high DI/DT appears on this pin. Keep the external bypass and capture the diodes close to this pin. All tracking of the inductance on this path will generate a voltage peak at the switch and increase the VCE voltage of the internal NPN.

Boost (pin 3): Boost pins are used to provide internal voltage higher than the input voltage bipolar NPN power switch. If there is no typical switching voltage loss of this additional voltage, the additional voltage voltage of 1.5V allows the switch saturated voltage loss to the 0.2ΩFet structure. Efficiency increases from 75%of the traditional bipolar. The design ratio of these new parts exceeds 88%.

GND (pin 4): There are two reasons to consider that the GND pin connection is connected. First, it is used as a regulating output, so if the ground " end voltage of the load and the grounding of the integrated circuit. This situation will occur at the metal path between the current or other current flowing through the ground pins and the load ground when loading. Keep ground pins and loads and use ground planes as much as possible. The second consideration is EMI caused by the peak of the GND pin. The capacitance of the internal VSW pin and GND pins generates extremely narrow ( lt; 10NS) current peak at GND pins. If the ground pins are connected to the system grounding traces with long metals