Features

Fully enhanced the N -channel power MOSFET

8μA IQ. Capacitor

4.5V to 18V power supply range

Short -circuit protection

Pleurate the heat shutdown through PTC thermistor

Status output indicator shutdown

[123 ] Provide 8 stitches SOIC

Application

Last computer power supply switch

SCSI terminal power supply switch

Honeycomb phone power management

battery charging And Management

High -end industry and automotive switch

Step motor and DC motor control

Description

LTC1154 single high grid drive allows permission The cost of the use of low -side switching applications N channel field effect transistor. The internal charge pump increases the gate driver voltage above the track, which fully enhances the switch of the N -channel MOS without external components. Micro -power operation, 8μA spare current and 85μA working current, allows maximum efficiency in almost all systems. The chip includes a programmable over -current detection. You can add a time delay to prevent errors from triggering high impact current loads. The activated high -stop input also provides and directly connects to the standard PTC thermistor used for heat clearance. Open leakage output is used to report the switch state to μP. Effective low level enable inputs to control multiple switches in control. LTC1154 has 8 -needle DIP and 8 -needle SOIC packaging.

All components are installed on the surface.

IMS026 International Manufacturing Service Company (401) 683-9700 If the load is a resistance or induction load, it is not needed.

absolute value

Power voltage 22 volt

Input voltage (vs+0.3V) to (GND-0.3V)

Enable input voltage (vs VS +0.3v) to (GND-0.3V)

Gallery voltage (vs+24V) to (GND – 0.3V)

Status output voltage 15 volts

current (Any pins) 50 mAh

Work temperature

LTC1154C 0 ° C 0 ° C to 70 ° C

Storage temperature range –65 ° C to 150 ° C

Lead temperature (welding, 10 seconds) 300 degrees Celsius

Electric characteristics vs u003d 4.5V to 18V, TA u003d 25 ° C, VEN u003d 0V, vsd u003d 0V, unless there is another explanation.

indicates the specifications suitable for working temperature.

Typical performance features

Input and close pins

The LTC1154 input pin is in a high -level activation state and activates all the protection and charge pump circuits at the time of opening. Turn off the sales design to be detected immediately if the second failure (too high temperature, etc.) is detected. LTC1154 Logic and stop input high impedance CMOS doors have ESD protection diode grounding and power supply, so it should not be forced to exceed the power rail. When the stop selling is not used, it should be grounded.

Enable input pin

Enable input to enable

LTC1154 high -voltage side switch group or provide auxiliary control methods. It can also play a reversal input. The enable input is a high -impedance CMOS door using ESD clamping diode grounding and power supply, so it should not be forcibly beyond the power rail. When not in use, the pin should be ground. In the following circumstances, the switch is turned off or driven to the above -top switch to be turned on. This needle is relatively high in the impedance when driving above the orbit (equivalent to hundreds of K ). Pay attention to minimize the land parasitic resistance or supply.

Power pins

The power pins of the LTC1154 have two important uses. The first one is obvious: it is powered by input, gate driver, adjustment and protection circuit. The second purpose is to be less obvious: it provides a Kailvin connection to 100 millivol to internal drain resistance. LTC1154 is designed to supply continuous power, so the grid of MOSFET is always actively driven. If you need to cut off the power and then re -apply, the input pin (or enable pins) should be re -reset and the input lock and protection circuit should be replaced within a few milliseconds after re -connecting the power. In addition, this input and enable pins should be quarantine from the 10K resistance isolation limit to the power supply foot through the ESD -protected current. The power insertion of LTC1154 should not be forcibly inserted and may cause permanent damage equipment. 300 The resistor should be inserted in series if the negative power supply voltage transient is expected.

Differential response sales

Compare the discharge induction sales with fuel supply sales. If the voltage at the pin of the needle is lower than the 100 millivol to the feet, the input locks will be reset, and the MOSFET gate will be unloaded quickly. Cycle input, or enable input, reset the short -circuit lock and rotate MOSFET back. This pin is also a high impedance CMOS gate and ESD therefore should not be forcibly exceeded the protection range of electrical rails. In order to destroy over -current protection, the emission induction is shortened to the power supply. Some loads, such as large power capacitors, lights or motors, require a high impact current. RC delay can be added between sensing resistance and drain to ensure that the drain detection circuit is not triggered when it does not start. You can set this time constant from a few seconds to a few seconds. However, a long time delay may cause MOSFET to face the danger of being destroyed due to short circuit. (See the first section of the application information).

Status Pin

Status pins are a low -driving leakage output when the failure is detected. The 51K rally resistance should be connected to this output and logic power supply. The status pins of multiple LTC154S can be or, if no independent fault detection is required. No need to connect to the pin when not in use.

The truth display shows how LTC1154 receives to μP input and returns status information from μP. The input signal control switch is normal In the working mode, the grille driver is controlled to rise and fall to limit the electromagnetic interference and radio frequency interference emissions. However, the shutdown and over -current detection circuit shut down at a higher rate of exposure to the exposure of the grid to the MOSFET switch and the load. The state pin is kept at a high level because the switch is normal, only when the low level is detected when the failure is detected. Note that the shutdown pin is sensitive on the edge, even if the shutdown pin returns low state.

LTC1154 Operation

LTC1154 is a single -micro power MOSFET driver built -in protection, status feedback and door charge pump.

LTC1154 consists of the following functional blocks: TTL and CMOS compatible input LTC1154 input and close input have been designed to adapt to a wide range of logical series. Both input thresholds are set to approximately 1.3V, and the lag is about 100mV. Low-standby voltage regulator provides continuous bias for the TTL-CMOS converter. The output of the TTL to the CMOS converter makes the remaining circuits realize. In this way, in the standby mode.

Enable input

Enable input to be compatible with CMOS and inhibit the input signal, no matter when the logic is high. This input should be ground when it is not used.

Internal voltage adjustment

The output driver from TTL to CMOS converter two drives two voltage voltage power supply logic and analog blocks for low voltage CMOS power. The regulator output is isolated from the noise pump logic of the charged no coupling to 100MV reference or analog comparator.

Door charge pump

The gate driver of the MOSFET switch by the MOSFET switch is far higher than the power supply voltage that generates a grid's adaptive charge pump. Charge pumping electricityThe container includes a chip and therefore no external component to generate door drivers.

Leakage current detection

LTC1154 configuration to inductive current in high -voltage side applications, injection power MOSFET drain. Compare the internal 100 millivolo reference voltage and voltage to compare the sensor (usually 0.002 to 0.10 ) to connect with the drainage pipe. If the voltage on this resistor drops more than the internal 100 millivolo threshold, after entering the lock memory reset, a large N -channel transistor tube is passed.

The lift time of the control gate

When the input is opened and closed, the door is charged by the internal charging pump and is controlled by the internal charging pump. The charging and discharge rate is set to minimize RFI and EMI launch operations under normal circumstances. If the short -circuit or current is over load, when this is the case, the gate is quickly discharged by a large N -channel transistor (usually a few micro seconds).

Status output drive

The state circuit continuously monitor the logic of fault detection. When the grid of MOSFET is protected by the protection of the drive circuit. The status circuit is locked while the input or enable input is locked together.

MOSFET and load protection

LTC1154 Protect the power MOSFET switch in the following way Once the current occurs, remove the drive from the gate to detect the condition. Resistance and inductance loads can be no external delayed protection of emissions sensing. However, the lamp load is required to be long enough but short enough to ensure a safe MOSFET.

Resistance load

The main thing is that the load of the resistance should be delayed as short as possible to minimize the time MOSFET is in a overload state. The drain detection circuit has a built -in delay of about 10 μs to eliminate the error trigger or load transient conditions of the power supply. This delay is sufficient to ""shield"" short -term load current and small capacitors (u0026 lt; 1 μF) that is connected to the load. Therefore, induction sales can be directly connected to the drainage pipe current to detect the resistor, as shown in Figure 1.

Sensitive load

is mainly sensitive loads. For example, relay, electromagnetic coils, and step motor winding should be protected as short as possible to minimize the time conditions for the number of MOSFET overloads. The built -in 10 μS delay will ensure that over -current protection will not be transmitted due to power or load. No external delay components are required as shown in Figure 2. Large sensor loads (u0026 gt; 1.1MH) may require a diode to directly connect to the sensor to safely transfer the storage energy to the ground. Many inductive loads include these diode. If not, the diode with an appropriate rated current shall be connected across the load, as shown in the figure 2. The energy stored in safe transfer storage.

Capacity load

Large -scale capacitance loads, such as complex electrical systems with large bypass electrical containers, should use the circuit shown in Figure 3. The gate is delayed through the RC delay network, R1 and C1 through the RC, which greatly reduces the switch. Because of the source voltage of the MOSFET, the load is smooth and slowly powered on the ground. This greatly reduces the start -up current of inflowing power supply containers. In turn, reducing the power supply transient and allowing slower start -up sensitive electrical loads. (The diode D1 provides a path for a direct LTC1154 protection circuit to quickly release the grid charge under overcurrent).

RC network, RD and CD, and the interconnection with the leakage should be set to the input settings according to the expected characteristics of the load after startup. In this circuit, it is likely to supply a large capacitance load, but there is still a state of reaction quickly becoming overcurrent. The output when the switch leaves the ground is: dv/dt u003d (vgate -vth)/(R1 × C1)

Therefore, the startup time is about: Istart-up u003d CLOAD × DV/DT use Figure 3 The value shown is less than 100mA, which will not erly trigger the leakage settings to 2.7A, and the delay 1MS sensor circuit

Light load The current is 10 to 20 times the current working current. The circuit shown in FIG. 4 changes the current limit threshold increase of 11: 1 (to 30A), and the bulb is opened first 100ms. The current limit is reduced to 2.7A after weakening the peak current.

Select RD and CD

FIG. 5 is a standardized over -current offset diagram and standardized MOSFET current. This picture is used to select two delay components, RD and CD, and form a simple RC delay resistance and drain detection input between the leakage.

The y -axis standardization of FIG. X -axis specifications to current. (Scene) current is defined as the current of 100 millivolves required for development to detect the resistor through the drain). Note that over time, the shutdown time shorten the MOSFET current level. This can ensure that the energy scattered by MOSFET is always the boundary between the manufacturer as a security operation. (For more information, see the MOSFET data table). Under the short circuit of accelerated diode to reduce power MOSFET, a small signal diode of the ""bypass"" delayed resistor is shown in Figure 6. When the diodes are dropped when the voltage is dropped through the leakage sensor, the combination of about 7V provides a direct sensing of about 7V and greatly reduced

MOSFET is in a overload state. Leakage selection resistance value to limit the maximum DC current as the drain current exceeds 20A, shortening time to 15 μsEssence Battery reverse protection LTC1154 can prevent the battery from discharging reverse discharge by connecting a resistor to the grounding line in Figure 7. The resistor limits the power supply current less than 50mA, and the -12V is applied.

Because the LTC1154 was minimized when the LTC1154 was running normally. 5V μP (or control logic) input and state pins by 10K resistance series and state pins.

Flowing power supply

LTC1154 requires the power pins at least 3.5V to ensure that the operation is normal. Therefore, it is necessary to maintain the power supply voltage of the LTC1154 at a level higher than 3.5V, even if the output of the switch is short -circuit. The output voltage of the current limit regulator may drop quickly and drive the power supply foot of the LTC1154 to be less than 3.5V. When the turning circuit has time to respond and remove the driver, the grid of the power MOSFET is removed. Supply filter should be

As shown in Figure 8, the length of the power supply foot LTC1154 is sufficient to withstand the current closing circuit to respond and completely discharge the door. The most difficult to protect the five -volt stabilizer with a small output capacitor, because they can quickly change from the voltage mode to a current -limiting mode. The large output capacitance on this switch regulator can keep the power pins of the LTC1154 at more than 3.5V and no additional filtering. Because the LTC1154 is micro -power in the two standby conditions, in the connection state, the voltage drop on the power filter is less than 2mv, and it will not significantly change the accuracy of the 100MV drain detection threshold voltage.