Features

high power 5V to 1.xv-3.xv switch controller: can output more than 10A

maximum duty cycle gt; 90%, allow 3.3V To 2.xv

Use 5V low -power power supply for conversion

All N -channel outer MOSFET

Frequently operating small L

excellent output adjustment: More than the line ± 1%, load

and temperature change

High efficiency: 95%or more

No low -value response resistor is required

Output can drive Gundam Gundam

10000pf grid capacitance

Static current: 350 μA typical values, 1 μA

Quick transient response

adjustable or fixed 3.3V output [ 123]

There are 8-line SO and 16 line GN

So packaging

Pentium power supply

II and AMD-K6 #174;

Micro Processor

Local regulations of high power 5V to 3.xv regulator

Dual voltage logic board

Low -voltage, large current battery adjustment

Instructions [ 123]

LTC #174; 1430A is a high-power, high-efficiency switching power supply optimizer controller for 5V to 1.xv-3.xv applications. It includes a accurate internal reference and an internal feedback system rotation system that can provide ± 1%of the temperature, load current, and line voltage output adjustment.

LTC1430A

Use a synchronous switch structure with two N -channel output equipment to eliminate a high -power and high -cost P channel device. In addition, it can sensorize the resistance of the upper part of the output current of the leak source source, which provides a adjustable current limited resistor without external low -value sensing. The LTC1430A includes a fixed frequency PWM oscillator under almost all operating conditions, and the output ripples are low. The frequency of 200kHz free run clock can be adjusted from 100kHz to above 500kHz. The maximum occupy ratio of this LTC1430A is usually 93.5%, while the maximum duty cycle of LTC1430 is 88%. This allows 3.3V to 2.xv to use 5V low -power power supply for conversion. The LTC1430A has a static current of 350 μA, which allows larger to output current from 1A to 50A. The shutdown mode drops the LTC1430A power supply current to 1 μA. A UG WA WU B absolute value

Power supply voltage

VCC 9 volts

Pvcc1, 2 13 volts

Input voltage

Bidding — 0.3 volt to 18 volts

All other inputs — 0.3v to (VCC+0.3V)

] 150 degrees Celsius

Work temperature range

LTC1430ac 0 ° C to 70 ° C

LTC1430AI – 40 ° C to 85 ° C

Storage stored storage storage Temperature range -65 ° C to 150 ° C

Lead temperature (welding, 10 seconds) 300 degrees Celsius

Electric characteristics

VCC 5V, TA 25 ° C ( Note 2), unless there is another instructions

electrical characteristics

VCC 5V, TA 25 ° C (Note 2), unless there is another instructions [ 123]

indicates the standard temperature range suitable for the entire operation.

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

Note 2: The current of all entering device pins is positive; the current output from the device is positive. Unless there are other regulations, all voltages are clearly stipulated in reference.

Note 3: The current power supply current at normal operation needs to charge the external FET door. This will use FET with LTC1430A working frequency, working voltage and external use.

Note 4: ILIM amplifier can absorb current, but cannot provide a current source. The ILIM output current will be zero below normal (not subject to current restrictions).

Note 5: The opening DC gain of the FB pin and the transmissions (Sense+and Sense – Floating) to the COMP pins will be av and GMV separately

Typical performance features

G1 (pin 1/pin 1): Drive output 1. Connect this pin to the gate of the upper N -channel MOSFET, Q1. This output will be transferred from PVCC1 to PGND. When G2, it is always very low.

PVCC1 (pin 2/pin 2): Power VCC of Driver 1. This is the G1 power input. G1 will swing from PGND to PVCC1. PVCC1 must be connected to at least PVCC+VGS (open) (Q1). This potential can be connected to the upper MOSFET and the lower MOSFET with an external power supply or a simple charge pump; please refer to the application information for details.

PGND (pin 3/pin 3): power supply ground. Both drivers returned to this needle. it shouldConnected to the source of low impedance ground near Q2. 8-The leading parts are connected to the pins of 3 pins.

GND (pin 4/needle 3): signal ground. All low -power internal circuits return to this pin. Try to reduce the adjustment error due to the ground current, GND should be connected to the PGND of the LTC1430A. The 8 -lead parts are connected to PGND and GND in the internal pins 3.

Sense -, FB, Sense+(pin 5, 6, 7/needle 4): These three pins are connected to the internal resistor division and internal feedback nodes. Use the internal partition to set the output voltage to 3.3V, and connect to the terminal and induction ground to the positive output capacitor. Food and beverages are used internally. Set output voltage, float sensor+and induction-and connect the external resistor to FB with the external resistor division.

SHDN (pin 8/pin 5): Close. When TTL compatible with low SHDN exceeds 50 μs, the LTC1430A will shut down mode. In the shutdown state, both G1 and G2 will turn lower internal circuits to be disabled. When the static current is SHDN, the maximum is reduced to 10 μA. TTL is compatible with high levels to allow components to work normally.

SS (pin 9/na): Soft start. SS pin allows external connection capacitors to achieve soft startup function. The startup time and compensation current restriction loop from SS to the ground to the ground allows LTC1430A to enter and exit the current restrictions. For details, see the application information.

Compensation (pin 10/pin 6): external compensation. The company's pin is directly connected to the output end of the error amplifier and the input of PWM. Here is a node that uses the RC network compensation feedback circuit to provide the best transient response. For related, please refer to the application information salary details.

Freqset (pin 11/na): frequency settings. This pin is used to set the free operating frequency of the internal oscillator. As the pin floats, the oscillator runs about 200kHz. The resistance from Freqset to the ground line will accelerate the oscillator; VCC resistance will slow down it. For more information on the selection of resistors, see the application information.

IMAX (inserted 12/na): Set current limit. IMAX sets the threshold of the internal current limit comparator. If IFB drops when G1 is opened, lower than IMAX, LTC1430A will enter the current limit. IMAX has 12 μA pulled down to GND. It can adjust the external resistance or external voltage source of PVCC.

IFB (pin 13/na): current restrictions. The exchange node connected to the Q1 source and Q2 leakage via 1K resistance. It is required to prevent the voltage caused by the destructive IFB. This unintellable can be ground voltage up to 18V,No damage.

VCC (pin 14/pin 7): power supply. All low -power internal circuits extract the power from this step. Connected to a clean main power supply separately from the main power supply Q1 drainage pipe. This pin requires 4.7μF or higher bypass container. 8 Dissue components to connect VCC and PVCC2 together need at least 10 μF bypass to GND.

PVCC2 (pin 15/pin 7): Power VCC of Driver 2. This is the power input of G2. G2 will be transferred from GND to PVCC2. PVCC2 is usually connected to the main power supply. 8 Dissiler components connect VCC and PVCC2 to pins together 7 and require at least 10 μF to bypass to GND.

G2 (pin 16/pin 8): Drive output 2. Connect this pin to the lower N channel MOSFET grid, Q2. This output will be transferred from PVCC2 to PGND. When G1, it is always very low.

Application information Overview: LTC1430A is a voltage feedback PWM switch regulator controller (See Fragments) Design is designed in a high -power, low voltage antihypertensive (BUCK) converter. It includes a plate PWM generator, a precise reference value adjustment to ± 0.5%, two high -power MOSFET gate drivers and all necessary feedback and control circuits to form a complete switching voltage voltage circuit. The pulse width adjustment ring is nominally running with 200kHz. The 16 -drawing version of the LTC1430A includes a current with a limit sensing circuit MOSFET using the upper external power supply as an current sensing element, eliminating an external sensing resistance. The 16 guide version also includes only one external capacitor operation. In addition, 16 lead components have adjusted oscillator, which can increase the flexibility selection of external components from 50kHz to 500kHz. The 8 -led version does not include current limit, internal soft start or frequency adjustment.

Operation theory

Main feedback circuit

LTC1430A induction circuit output voltage belt with the output capacitor of Sense+and Sense-pins and feedback this voltage to the internal cross-guide amplifier to the inside cross-guide amplifier FB. FB compares the resistance output voltage with the internal 1.265V reference voltage, and then outputs an error signal sent to the PWM comparator. Then compare it from the generated fixed frequency jagged wave to generate pulse width modulation signals from the internal oscillator. This PWM signal is fed back to the external MOSFET through G1 and G2, closed the loop. Cycling compensation is the output node of the FB cross -guide amplifier through external compensation.

The two additional comparators in the minimum and maximum feedback circuit provide not to respond quickly in the FB amplifier. MIN is more antiThe feed signal to the voltage of less than 40 millivolves (3%) internal reference. At this time, the smallest comparator Super Chi FB amplifier and the full load cycle of the ring road, set up from the internal oscillator to about 93.5%. Similarly, the MAX comparator monitoring the output voltage is higher than the internal reference value of 3%, and the duty ratio of 0%when the output is output. These two comparators can prevent extreme output disturbances through rapid output, and at the same time allow the main feedback circuit to compensate for the best stability

Flow Limited Circuit

16 LTC1430A device also includes another feedback Detaiser is used to control operations under current limit. The current limit circuit is disabled in the 8 -line device. ILIM amplifier monitor the voltage on external MOSFET Q1 as high as G1. It compares this voltage with the voltage on the IMAX pin. When the peak current rises, the RDS (opening) increases. When IFB is lower than the IMAX, it means that the leakage current of the Q1 exceeds the maximum value, and ILIM began to draw a current capacitor from the external soft start to reduce the duty cycle and control the current level. At the same time, the ILIM comparator generates a signal to disable the minimum comparator to prevent conflict with the current limit circuit. If the voltage of the internal feedback node drops below 0.8, indicates that the serious output overload will be indicated, and the circuit will slow the internal oscillator. Undertake short circuit unlimited overcurrent conditions. Use Q1's RDS (ON) to measure the output current, and the current limit circuit is eliminated. Otherwise, it will be required and components in the external large current circuit diameter. Because the power MOSFET RDS (on) is not strictly controlled, and the changes are under temperature conditions, the current limit of the LTC1430A is not accurate; it is to prevent the power circuit in the state of damage. When the actual current limit circuit starts to take effect, the current level may be different according to the power, and MOSFETS may be used. For details, please refer to the details of soft startup and current restrictions.

Application information

MOSFET gate driver

provides a gate driver from PVCC1 for the top N channel MOSFET Q1. The power supply must be higher than the PVCC (main power input) and operate effectively by at least one power MOSFETVGS (on). The internal level converter allows PVCC1 to run at a voltage higher than VCC and PVCC, with a maximum of 13V. Can provide higher voltage or simple charge pumps are shown in Figure 5. When using a separate PVCC1 power supply, PVCC input may show that if PVCC1 occurs during power -powered, it will flow. This 93.5%maximum duty ratio ensures that the oil supply pump will always provide sufficient door drive to Q1. The bottom of the door drive MOSFET Q2 provides a VCC/PVCC2 of 16 -line devices or 8 -line devices through PVCC2. PVCC2 type can usually be directly from the PV of 16 leader 16The CC driver can also connect the charge pump or parts if it is required to provide a spare power supply. 3.3V input is applied to use 3.3V at PVCC, and 5V is used at VCC and PVCC1. See 3.3V input to provide operations to understand more details. The 8 lead part of the lead needs to be operated from PVCC to VCC to ensure the correct operation; see the precautions for input power.

LTC1430A adopts a synchronous switch structure, MOSFET Q2 instead of the diode classic antihypertensive circuit in A ( Image 6). This can improve efficiency by reducing voltage and lowering from Q2 to VON (i) (RDSON (q2)), usually much lower than the VF of the diode in the traditional circuit. This exceeds the required additional gate driver through the second MOSFET, which makes the LTC1430A efficiency of about 90%, suitable for various load currents.

Another feature of the synchronization architecture is that unlike the diode, Q2 can conduct current in any direction. This makes the output attenuation of the typical LTC1430A circuit flowing and purchasing it under the premise of maintaining supervision. The ability to absorb current at the output end allows the LTC1430A to react or other unconventional may provide current to the regulator to provide current and absorb current from it. An example is the high -current logic terminal power supply, such as the typical application part of the GTL terminal shown in it.

Outside component selection

Power golden oxygen semi -electrocarmoid

MOST needs two N -channel power MOSFETLTC1430A circuits. Selected according to threshold and resistance; thermal dissipation is usually the second high -efficiency design. The required MOSFET threshold should be based on the complexity of the available power supply voltage and the/or door drive charge pump

In the 5V input design, the auxiliary 12V power supply can be the standard MOSFET PVCC1 and PVCC2 power in VGS 5V or or Specify RDS (open) when 6V, which can be good with the effect. The current from this power supply is different from the frequency of using MOSFET and LTC1430A, but generally less than 50mA. The LTC1430A design uses the multiplier charging pump to generate a gate driver to Q1, and runs below 7V from the PVCC voltage that cannot provide sufficient grid drive voltage to enhance the standard power MOSFET. When running at 5V, the A double-frequency circuit can work with the standard MOSFET, but the MOSFET-RON may be quite high, increasing FETS and cost efficiency. Logic level FET is a better choice for the 5V PVCC system; they can fully enhance the charge pump and will be the highest efficiency. The voltage of the multipliers running from PVCC will begin to occur if the voltage of 4V will begin to occur. Even if the logical grade FET is used, it should also be established to use such a three -twice charging pump(See Figure 7) or update, ultra -low threshold MOSFET. Note that the design of double charge pumps runs from 7V above 7V, and the full three times charge pump design should include DZ at the Qina clamp diode PVCC1 to prevent the absolute maximum rated value of the stance exceeding the pin.

Once the threshold voltage is selected, RON should choose according to the input and output voltage, allowing power consumption and maximum output current. In a typical LTC1430A antihypertensive converter circuit, the average electrical sensor current is equal to the output load current. The current is always through Q1 or Q2, and the power consumption is separated according to the duty cycle:

The RON required for the given conduction loss can now be re -arranged. P P P I2R calculation:

PMAX should mainly calculate the efficiency according to the requirements. A typical 5V high -efficiency circuit input, the 3.3V voltage during 10A output requires no more than 3%of the efficiency loss of each MOSFET at full load. Assuming that at the current level, about 90%of the efficiency PMAX value (3.3V) (10A/0.9) (0.03) 1.1W/FET and the required RON:

[123 ] Note that the RON required for Q2 is about Q1 in this example. This application may specify a single 0.03 #8486; the device is Q2 and more than two or more. It should also be noted that the value indicates that the MOSFET is large, and the scattered number

A very practical program

Each device is only 1.1W or smaller-large to 220 packs. Need radiator. Silicon SI4410DY (in SO-8) and Motorola MTD20N03HL (in DPAK) are two small, the surface installation RON value is 0.03 #8486; or lower 5V device door drives; Work well to 10A output current. The higher PMAX value usually reduces MOSFET costs and circuit efficiency, and improves MOSFET heat sink requirements.

Electrochemical

The inductor is usually the largest component design and choice in LTC1430A. The inductor value and the type selection type should be selected according to the output conversion requirements and the expected peak current. The inductor value is mainly controlled by the required current conversion rate. The maximum increase rate of this sensor current is based on its value, the input output voltage difference and the maximum occupation ratio of the LTC1430A. In the typical 5V to 3.3V applications, the maximum rise time is:

, L is an inductor value in the unit of μH. The 2 μH inductor will be applied here to 0.76A/μs, resulting in a delay of 6.5 μs in response to the 5A load current. During this period 6.5μs, inductanceThe instrument current and output current must be compensated by the output capacitor, causing the output current to temporarily decrease. Under the influence of minimizing, the inductor value should usually be 1 μH for the most typical 5V to 2.xv-3.xv LTC1430A, and the range is 5 μH. Different combinations of input and output voltage and expected loads may require different values. Once the required value is known, the type of inductor iron core can be selected according to the peak current and efficiency. The peak current in the inductor is equal to the maximum output load current plus half of the inductive peak ripple current. The ripple current consists of electrical sensor value, input and output voltage, and working frequency. If the efficiency is about 1, the ripple current is about equal to:

The iron core of the inductor must be sufficient to withstand the peak current, the copper resistance winding group should be as low as possible, so as to be as low as possible, so Minimize resistance power loss. Note that the current may rise to the failure of the maximum level of unlimited circuit in the circuit that is lower than or lower than the current limit;

Input and output capacitors

The typical LTC1430A design pairs of input and output capacitors. The load runs under normal stability state. For example, the antihypertensive converter of the LTC1430A comes from the square wave current switching frequency of the input power supply. Most of the current must come from the input bypass container, because few raw materials can provide the current conversion rate to feed this kind of thing directly. The generated square root current will heat it in the input capacitor, causing a capacitor failure under premature extreme situation. When the maximum balance of the root current occurs when the PWM duty cycle is 50%, the generated square current current is equal to 2. Low ESR input capacitors must use enough ripple current rated values u200bu200bto ensure reliable operation. Please note that the rated value of the ripple current of the capacitor manufacturer is usually based on the life span of 2000 hours (3 months); the input capacitor further reduces the ripple current that exceeds the manufacturer's specifications.

The output capacitors in the Buck converter see less stable and stable conditions are greater than the input capacitor. Peak current is equal to inductors, usually accounting for a small part of the total load current. The output capacitor occupies the duty ratio without considering power consumption but low blood. During the output load transient state, the output capacitor must provide the current required to all the additional load load until the LTC1430A can adjust the sensor current to the new value. The ESR output capacitor causes the output voltage level to jump equal to the ESR value multiplied by a load change current. The 5A load order jump with 0.05 #8486; ESR output capacitor will cause 250 millivoltage output voltage to shift; this is the output voltage offset of the 7.6%3.3V power supply! Because the output capacitance ESR and the output load transient response, the output capacitor is usually selected ESR, not the capacitor value; A has a capacitance with appropriate ESR.

The electrolytic capacitor for the rated switching power supply has fingerFixed -line wave current rated value and ESR CAN power supply is suitable for the LTC1430A application. OS-Cons Sanyo's electrolytic container has excellent performance and has extremely high performance/size than electrolytic capacitors. Surface -installed applications can use electrolytic or dry capacitors. The capacitor must be tested and specified for switching power supply; low -cost universal alloy is known for short life, and then the death of the switch power supply application. The AVX TPS series of surface installation devices is a common 钽 capacitor, working well in the LTC1430A application. The method of normal reduction of ESR and the ability to improve ripple current is to connect several capacitors in parallel. The typical LTC1430A application may require a 5A ripple input capacitor current capacity and 2%output displacement. The 10A output loan is entered, and the output capacitor ESR is required for 0.007 #8486. Sanyo OS-CON part number 10sA220M (220 μF/10V) capacitors at 85 ° C have 2.3A allowed ripple currents and 0.035 #8486; ESR; three parallel connection at the input end, and six parallel parts at the input end will meet the input end. The above requirements

Input Power Note/Charging Pump

16 Direct LTC1430A requires four power supply voltage operations: PVCC, PVCC1 and PVCC2 cleaning and low ripple driver in the main power supply MOSFET CLTC1430A Circuit (Figure 8). In many applications, PVCC and PVCC2 can be connected together and have high voltage voltage from ordinary high -power power supply, which can fully enhance the external gate MOSFET Q2. This can be a 5V system power supply, if the logic level MOSFET is used for Q2. VCC can usually filter static current (usually 350 μA) that is powered by the same high -power power supply (usually 350 μA) allows the filter resistance to be relatively large and the corresponding smaller filter capacitor. 100 #8486; and 4.7μF usually provide AD equivalent filtering for VCC. The 8 -draw version of the LTC1430A has a unique needle tied together in the packaging (Figure 9). This other needle, as a VCC/PVCC2, has the same low ripple requirements as the 16 -drawing component, but must also be able to provide a gate -drive current to Q2. This can be obtained

Use a larger RC filter from PVCC pins; 22 #8486; and 10 μF works well here. The 10 μF capacitor must be very close to the component (preferably directly below the device) or output supervision may be affected. For the two versions of the LTC1430A, PVCC1 must be higher than that of PVCC at least one external MOSFET VGS (on) to fully enhance the Q1 door. The higher voltage can provide a separate power supply (usually 12V), which should be powered after PVCC, or you can use a simple charge pump (Figure 5). The oil supply pump includes PVCCFrom PVCC1 and 0.1 μF, the Schartki diode from PVCC1 to capacitive problems 2. This circuit provides 2PVCC -VF for PVCC1, Q1 is ON and PVCC -VF, and Q1 is OFF. Among them, VF is the voltage of the ON Schottky diode. Q2 Drainage port sounding may cause the transients at PVCC1 to be higher than 2PVCC; if PVCC is higher than 7V, 12V Zina diode should include PVCC1 to PGND to prevent transient damage to PVCC2 or Q1 door circuits. The more complicated charge pump can provide an additional voltage with a low PVCC voltage used with the 16 leading versions of the LTC1430A to provide additional voltage with the standard threshold MOSFET. The three -fold charge pump (Figure 7) can provide 2PVCC and 3PVCC voltage. They can be connected to PVCC2 and PVCC1 respectively, allowing standard threshold MOSFET to use the logical flat threshold MOSFETPVCC company with 3.3V AT when PVCC or 5V. VCC can drive from the same potential as PVCC2 to allow the entire system to run under a 3.3V voltage. The three -fold charging pump needs to use the Schottky diode to minimize the positive pressure drop of the diode. The three -fold charging pump circuit will tend to correct any sound of the Q2 drainage port, and can provide a good PVCC1 exceeding 3PVCC; all three times frequency (or higher multiplication coefficient) circuit shall include 12V Qina diode DZ to prevent PVCC1 from passing PVCC1 Voltage

3.3V input power operation

LTC1430A can be used below 5V with the input power supply voltage. As long as 5V low power power supply is LTC1430A itself, and is an external MOSFET. The typical 3.3V to 2.5V application is shown in Figure 10. The circuit is output at 2.5V and obtained this power supply from 3.3V power. The 5V power supply usually needs to provide a gate driver to the external MOSFET and keep the LTC1430A control circuit power power. It is suitable for available without 5V power supply, please refer to the LTC1649 data. Compensation and transient response LTC1430A voltage feedback loop is in COMP PIN; this is an internal GM output node error amplifier. Circuit can usually be compensated

A very practical program

Via a small C (Figure 11 To. Circular stability is affected by inductance and output capacitors. The best circuit response to find the ring and zero through the use of the network analyzer to find the ring road; it is almost effective and easy to adjust the RC value according to the experience until the temporarily resume output loading steps look correct. Table 1 shows the application values u200bu200bof the recommended compensation element from 5V to 3.3V. Use multiple parallel 330 μF AVX TPS series surface stickers 钽 calculationThese value capacitors are used as output capacitors

The output transient response is determined by three main factors: the time constant of the inductors and the output capacitor ESR and ring circuit compensation component of the output capacitor Essence The first two factors usually have a lot of impact on the overall transient recovery time to the third. Unless the circuit compensation is too poor, more can be used by optimizing the sensor and output capacitors to compare the circuit compensation components. Generally speaking, the smaller inductance value will improve the transient response at the cost of sacrifice ripples

and the saturated rated value of the inductors. To minimize output capacitors ESR also helps optimize output transient response. For more information, see input and output capacitor information.

Soft startup and current limit

The 16 -lead version of the LTC1430A includes the circuit at the SS pin at the SS pin; the circuit is used for initial startup and current limit operation. Soft startup and current limiting circuits are disabled in the 8 -line version. Stainless steel requires an external capacitor to ground by the required soft start time. The inner line includes a 12μA current source for external charging capacitors. The soft startup function can swing the voltage that can be swinged by clamping the maximum compensation pin, thereby controlling the duty cycle (Figure 12). When the LTC1430A will start when the SS pin rises to about 2V, running below VCC at a low duty cycle. As the SS continues to rise, the duty cycle will increase until the error amplifier will be taken over and starts to adjust the output. When SS reaches VCC below 1V