Features

Ultra-power switch voltage voltage controller

It is used for 3.3V-5V to 1.xv-3.xv antihypertensive applications

No current fluid resistance resistance is required

Low input power supply voltage range: 3V to 8V

Maximum duty cycle gt; 91%ultra -temperature

All N channel external MOSFET

excellent Output adjustment: exceeding the line ± 1%, load and temperature changes

High efficiency: 95%or more

adjustable or fixed 3.3V output (16 -pin version)

Programmable fixed frequency operation: 100kHz to 500 kilohtz

External synchronization clock

Soft start (some model)

Low shutdown current: lt; 10μA ultra -temperature protection [123 123 ]

There are S8, S16 and SSOP-16 packaging

Application

CPU power supply

Multi-logic power generator

distribution Formulating Power Application

High-efficiency power conversion

Instructions

LTC #174; 3830/

LTC3830

-1 is a high-power, high-efficiency switch regulator Controller, used for 3.3V-5V to 1.xv-3.xv antihypertensive applications. The accurate internal reference and feedback system provides ± 1%output adjustment temperature, load current, and line voltage changes. LTC3830/ LTC3830-1 Use a N-channel synchronous exchange structure Mos Fitz. In addition, the chip induction output current passes through the leakage source resistance N channel field effect transistor of the above -mentioned leakage resistance, providing adjustable current limits without current resistance resistance. LTC3830/LTC3830-1 uses the working voltage of the input power supply to 3V, and the maximum duty cycle is gt; 91%ultra-temperature. They include a PWM oscillator running at a fixed frequency of low output ripples. The frequency of 200KHz free run clock can be adjusted or synchronized with external signals from 100kHz to 500kHz. In the shutdown mode, the LTC3830 power supply has dropped to lt; 10μA. LTC3830-1 is different from the LTC3830 S8 version. For similar, compatible DC/DC converters output voltage as low as 0.6V, please refer to LTC3832.

Most pair value

Power voltage

VCC 9 volts

pvcc1,2 14 volts

Input voltage

IFB, IMAX- 0.3 volts to 14 volts

Sense+, Sense -, FB,

SHDN, frequency setting -0.3V to VCC+0.3V

Jiev 125 degrees Celsius

Work temperature range (Note 9) -40 ° C to 85 ° C

Storage temperature range –65 ° C to 150 ° C

Lead temperature (welding, 10 seconds) 300 Celsius

Electrical characteristics

indicates the specification suitable for the entire working temperature

, otherwise the specifications are TA 25 ° C. VCC, PVCC1, PVCC2 5V, unless there is another instructions. (Note 2)

Electric characteristics

indicate the specification for the entire work temperature

, otherwise the specifications are TA 25 ° C. VCC, PVCC1, PVCC2 5V, unless there is another instructions. (Note 2)

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 be used with the working frequency, working voltage and external FET of the LTC3830.

Note 4: Open-loop DC gain and cross-guidance from sensory+and induction-pins to component pins will be (AV) (1.265/3.3) and (GM) (1.265/3.3).

Note 5: Rising and decreased at 10%and 90%measurement. Responsibilities use 50%horizontal measurement cycle and non -overlapping time.

Note 6: Design guarantee, without trial.

Note 7: For current, PVCC1 must be higher than VCC at least 2.5V to limit the protection circuit activation.

Note 8: The current limit amplifier can absorb current, but cannot provide current sources. Under normal (not limited by current), the output current is zero.

Note 9: LTC3830E/LTC3830-1E to ensure performance requirements from 0 ° C to 70 ° C. – 40 ° C to 85 ° C working temperature range is controlled by design, characteristics, and statistical process control sex.

Note 10: The minimum and maximum limit of IMAX ultra -temperature include the intentional temperature coefficient induction temperature coefficient of 3300PPM/° C to offset the typical temperature extra power MOSFET drive resistance coefficient. This will lead to a relatively flat current limitation of ultra -temperature applicationsEssence

Typical performance features

pin function (16 lead LTC3830// 8 Diversion LTC3830/LTC3830-1)

G1 (pin 1/pin 1/pin 1): upper grid drive output. Connect this pin connected to the gate of the upper N -channel MOSFET, Q1. The output is from PGND to PVCC1. If G2 is high or in the shutdown mode.

PVCC1 (pin 2/pin 2/pin 2): G1's power input. Connect the pin to the potential of at least VIN+VGS (on) (Q1). This potential can be pumped through an external power supply or oil supply.

PGND (pin 3/pin 3/pin 3): power supply ground. The two drivers return to this needle. Connect this pin to the ground with low impedance close to the Q2 source. See more details about PCB, please refer to the layout of some layout technology. LTC3830-1 and 8 Direction LTC3830 connect PGND and GND inside the pin 3.

GND (pin 4/needle 3/needle 3): Signal ground. All low -power internal circuits return to this pin. In order to minimize the adjustment error caused by the ground current, the GND is connected to the PGND at the LTC3830. Sense -, FB, Sense+(pin 5, 6, 7/needle 4/needle 4): These three pins are connected to the internal resistor separator and input end error amplifier. Use the internal partition to set the output voltage to be 3.3V, and connect Sense+to the terminal of the positive output capacitor and the negative polar terminal of the sensor. FB should keep floating. Use the external resistor division to set the output voltage, float sensor+and induction-and connect the external resistor to the FB. LTC3830-1 does not include internal resistor division and 8-line LTC3830.

SHDN (pin 8/pin 5/na): Close. When TTL compatible with low SHDN exceeds 100 μs, the LTC3830 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. This pinned needle also doubles as an oscillator with an external clock with the external clock as an external clock. The shutdown function is disabled in LTC3830-1.

SS (pin 9/na/pin 5): Soft start. Connect this pin to the external capacitor CSS to achieve the soft startup function. If the LTC3830 enters the current limit, CSS discharge reduces the duty cycle. The choice of CSS must ensure that the current of Q1 will not exceed the current limit level. Soft -start function is in the secondary 8 -drawing LTC3830.

Compensation (pin 10/pin 6/pin 6): external compensation. This pin is connected to the output end of the error amplifier and the input of the PWM comparator. Use the RC+C network to compensate the feedback circuit on this pin to provide the best transient response.

Freqset (pin 11/na/na): frequency settings. Use this PIN to adjust the free operating frequency of the internal oscillator. As the pin floats, the oscillator runs about 200kHz. The resistance from Frequeset to Group makes the oscillator accelerate; to the VCC resistance to slow down it.

IMAX (pin 12/na/na): current limit threshold settings. Maximum value Set the threshold of the internal current limit comparator. If the IFB drops below the IMAX when the G1 is turned on, the LTC3830 will run into the current limit. There are 12 μA drop -down land inside the IMAX. The main VIN power supply that connects this sales to the discharge port sets the current limit threshold through the external resistance. Connect a resistance of a 0.1 μF decouple capacitor to filter the switch noise.

IFB (pin 13/na/na): current restrictions. The exchange node connected to the Q1 source and Q2 via 1K resistance. The 1K resistor is required to prevent the voltage of transient damage. If this is the case, PIN is used to sensing the upper voltage drop N -channel MOSFET, Q1.

VCC (pin 14/pin 7/pin 7): Power input. They are all low -power internal circuits from this pin. Connect this pin to a clean power supply and provide the main VIN with the drainage outlet of Q1. This PIN requires 4.7 μF bypass electrical container. LTC3830-1 and 8 LTC3830 are connected to VCC and PVCC2 on the pin 7 and the need for 10 μF bypass capacitors.

PVCC2 (inserted 15/inserted 7/insert 7): G2's power input. Connect this pin to the main high -power power supply.

G2 (inserted 16/inserted 8/insert 8): output of the bottom grid drive. Connect this pin to MOSFET on the gate of the lower N channel, in the second quarter. Output from PGND to PVCC2. It is high in G1 or a short -term downtime. In order to prevent the output owes in the soft start -up loop, G2 kept at low until G1 rose for the first time. (FFBG chart in the block.)

Overview

LTC3830 is a voltage mode feedback, synchronous switching regulator control The device (see the square diagram) is designed for high -power, low -voltage antihypertensive (BUCK) converter. It includes a car PWM generator, a precision reference fine -tuning to ± 0.8%, two high -power MOSFET gate drivers and all necessary feedback and control circuits to form a complete switch regulatorCircuit. PWM Ring Road runs 200kHz nominally. The 16 -guided version of the LTC3830 includes a current -limited sensing sensing circuit power MOSFET using the upper external N channel as a current sensing element, eliminating an external sensing resistance. It also includes an internal soft startup function in the 16 leader version and LTC3830-1, and only one external capacitor is required. In addition, 16 lead components have adjustable oscillator and can run freely or synchronize to external signals. The frequency comes from 100kHz to 500kHz, which can increase the selection of external flexible components. The 8 -led version does not include current limit, internal soft start and frequency adjustability. LTC3830-1 does not include current limit, frequency adjustment, external synchronization, and closing function.

Operation theory

Main feedback circuit

LTC3830/LTC3830-1 sensing at the output capacitor, and feedback the internal interior cross-guided error of the voltage. Resistance division pressure device network. The error amplifier compares the voltage voltage of the resistance voltage with the internal 1.265V reference voltage, and the output error signal PWM comparator is compared. This error signal and fixed frequency slope waveform comes from the internal oscillator, generating pulse width modulation signals. This PWM signal via G1 drive external MOSFET and G2 pin. The generated wave wave shape closed the cycle through LO and COUT. Circular compensation is to achieve compensation pins through external compensation networks, and errors to place output nodes of large device. The smallest and maximum feedback circuit feedback circuit The two additional comparators in the loop provide high -speed output voltage correction errors, which may not respond fast enough. The youngest feedback signal is compared with an internal reference with voltage below 40 millivoli. If the signal is lower than the comparator threshold, the minimum comparator covers an error amplifier, and the compulsory circuit reaches the maximum duty cycle, gt; 91%.

ATIO application

Similarly, the maximum comparisoner output is 0%of the feedback signal greater than 40 millival, the duty ratio is higher than internal reference. In order to prevent these two components from triggered by noise, the response time of the minimum value and maximum value comparator deliberately delayed 2 to 3 microseconds. These two comparators have help to prevent extreme output disturbance load current by rapid output, and at the same time allow the main feedback circuit's stability to get the best compensation.

Hot shutdown

LTC3830/LTC3830-1 has a thermal protection circuit, which can be disabled by two door drives during activation. If the chip knot temperature reaches 150 ° C, both G1 and G2 are lower. G1 and G2 kept the low -level temperature drop below 125 ° C before the convergence point, and the chip resumed normal operation.

Soft startup and current limit

16 LTC3830 device includes soft startup circuits for startup and current limit operations. This LTC3830-1 has only a soft startup function; the current limit function is disabled. LTC388 Leading soft startup and current limit function is disabled. The stainless steel needle requires an external capacitor CSS to be determined by the required soft start time. The inside 12 μA current source is used for charging CSS. After the power is powered on, the COMP pin is sandwiched to the diodes (the connection of the QSS in the B-E (the QSS in the box diagram) is higher than the stainless steel needle. This can prevent the error amplifier from the maximum duty cycle. At 0.6V, run with a low -duty cycle (vicp≈1.2V). When the SS continues to rise, the QSS is closed and the error placing the large device is responsible for adjusting the output. The minimum comparator is prohibited during this soft launch to prevent it from covering the soft start of the soft start of the soft startup. Function.

16 LTC3830 device also includes another feedback circuit for controlling operations under the limit of current. Just at each decrease edge of the previous G1, current comparator, CC, sample and keep it on the outer upper part MOSFET, Q1, is located at IFB pin. The voltage at the IFB comparison of the IFB and the voltage at the IMAX tube. Below IMAX indicates that the leakage current of Q1 has exceeded the maximum level. The CC starts to pull the current outside the CSS, reduce the duty cycle and control the current level. The ratio and IMAX. In the case of slight overload, SS sales gradually declined, and a time delayed effect before current limit. Very short and slight overload may not affect the output voltage. The state, then the output keeps the lower voltage, until the overload is re -moved. Severe overload will be in CC, so that it can quickly pull the SS down and prevent the output component from damaging. By using RDS (opening), the output current is used to measure the output current, and the current limit circuit eliminates the elimination of the current limit circuit elimination. The expensive discrete sensor measured resistor, otherwise it is needed. This helps the number of components in the high current path. It can be supplied by the drainage port of the outer resistor RIMAX from the IMAX pin to the main VIN. :

OSC LTC3830 oscillator frequency 200kHz

LO inductor value

rds (on) q1 ilmax Q1 Direction resistance

IIMAX internal 12μ

q1 RDS (on) usually increases with the temperature increase. To maintain the current limit threshold, the leakage current of 12μA inside IMAX under IMAX is 12μA under IMAX leakage current under IMAX. The design provides the temperature coefficient of first -order correction to the temperature coefficient of the RDS (ON) Q1. In order to make the normal work of the current restriction circuit, in order to obtain a reasonable and accurate flow limit threshold IIMAX and IFB pin Foot. In addition, connect 0.1 μF to coupling through RIMAX's electricityContainer filter switch noise. On the other hand, the noise peak or ringing of the Q1 source will cause the actual current limit to the set value of the actual current limit than the required current limit. Due to the switching noise and RDS (ON), the actual streaming point is not high and accurate. The current limit circuit mainly refers to preventing the conditions of the fault. The accurate current horizontal circuit starts to take effect will change due to units. Generally, the changes in RDS (on) are ± 40%with the IMAX of the LTC3830, and the change to ± 25%current, which can limit the current limit of ± 65%. If the VGS applied to the MOSFET is low. This occurs during power -on, when PVCC1 tilted up. To prevent high RDS (ON) activation current, if the following situations occur, the LTC3830 will disabled current restricted circuit PVCC1 below 2.5V higher than VCC. To ensure the operation of an appropriate current restricted circuit, PVCC1 must be at least 2.5V higher than the VCC when G1 high. PVCC1 can be low. When G1 is lower, an external charge pump is allowed to use the external charge to the power PVCC1.

The frequency of the oscillator

LTC3830 includes a plate -load current control oscillator is usually freely run at 200kHz. The oscillator frequency can adjust the FreqSet pins through mandatory current. When the pin is floating, the oscillator runs about 200 kun. The 10kHz of the pins is set for each increase of 1 μA current input/output frequency. The internal servo of the pin to 1.265V, the 50K resistance connected from Freqset to the ground forced the 25μA output to run the internal oscillator at a frequency of about 450kHz. Forced an external 10μA current into Freqset to reduce the internal frequency to 100kHz. Internal clamping can prevent the operating speed of an oscillator below about 50 kg. Binding Frequeset to VCC will force the chip to run at this minimum speed. LTC3830-1 and 8 line LTC3830 do not have this frequency adjustment function.

Close

LTC3830 includes low -power shutdown mode, logical control of the SHDN pin. The climax of SHDN allows the part to work normally. SHDN's low level exceeding 100 μs will force the LTC3830 to close mode. In this mode, all internal switches stop, and the compressor stainless steel is pulled to the ground, Q1 and Q2 are closed. This LTC3830 power supply has dropped to lt; 10μA, but the external MOSFET corporal leakage may cause the vehicle recognition number (VIN) current to be higher, especially at high temperature. If SHDN returns high levels, the LTC3830 will re -run the soft start cycle and return to normal operation. This LTC3830-1 does not have this shutdown function.

External clock synchronization

LTC3830 SHDN pins are both an external clock input for applications that need to synchronize clocksEssence If the negative transition of the SHDN pin is detected. In this mode, the SHDN pin reset the internal oscillator and pull the slope signal low, which will force the LTC3830 to internal oscillator to lock to the external clock frequency. Is there any external synchronization function in LTC3830-1.

The internal oscillator of the LTC3830 can be synchronized from 100kHz to 500kHz. The frequency higher than 300kHz can lead to a maximum percentage of load reduction increase/decrease time and the period switch cycle of transmission. In the application of these circuit applications, it is important to check the frequency of frequency near dropout, such as 3.3V to 2.5V converters. The low cycle of the clock signal must be not greater than 100 μs, otherwise the LTC3830 enters the shutdown state mode. Figure 5 describes the operation of the external synchronization function. The negative leaps at the SHDN pin for compulsory internal slope signals are low to restart the new PWM cycle. Note that the slope amplitude in the traditional synchronization method decreases higher than the outer clock frequency. The effect of decreased slope amplitude increases the opening gain cycle of the controller feedback. Therefore, increased frequency of the ring circuit If the phase of the phase is insufficient. To solve this problem, the LTC3830 monitor the peak voltage of the slope signal and adjust the charging current of the oscillator to maintain a constant slope peak. Input Power Supply Precautions/Charging Pump 16 DRA LTC3830 requires four power supply voltage operations: VIN is used for the main power input, PVCC1 and PVCC2 are used for MOSFET gate drivers and a clean, low -grained VCCLTC3830 internal circuit (Figure 6). LTC3830-1 and 8 Direction LTC3830 connect PVCC2 and VCC pins together in the bag (Figure 7). This other needle brings the same low ripple requirements as the 16 leading part as the VCC/PVCC2. It must also be able to supply the port drive current to Q2. In many applications, VCC can pass the VIN power supply through the RC filter. This power supply can be as low as 3V low static current (usually 800 μA) allows the filter resistance is relatively large, and the corresponding is smaller

Filter capacitors. 100 #8486; and 4.7μF usually provide AD equivalent filtering for VCC. In order to get the best performance, please connect the 4.7μF bypass power container near the LTC3830 VCC pin component.

Provides a gate driver from PVCC1 for the top N -channel MOSFET Q1. This power supply must be higher than VIN (main power input) by at least one power MOSFET VG (open). The internal level converter allows PVCC1 to work at a voltage higher than VCC and VIN, with a maximum 14V. This higher voltage can be generated with a separate or charge pump. The grid driver at the bottom MOSFET Q2 is used by PVCC2 for 16-drawing LTC3830 or for LTC3830-1 and 8 leadLTC3830. This supply only requires efficiency operations higher than the power MOSFET VGS (on). PVCC2 can also be driven by the same power supply/charge pump for PVCC1, and it can also connect it to reducing supply to improve efficiency.

FIG. 8 shows a threex charging pump circuit that can be used to provide 2Vin and 3Vin door drive tops and bottom points. These should be enhanced MOSFET with a 5V logic level threshold. When the Q1 is connected, the circuit provides 3VIN -3VF2VIN -2VF to PVCC2 to PVCC1, where VF is the Schottky diode. The circuit needs to use the Schottky diode to minimize the front voltage drop of the diode. The three -fold charging pump circuit can correct any drainage outlet in the second quarter, and at PVCC1; PVCC1 should include a 12V Zina diode to prevent transient damage circuits from PVCC1 or Q1. When using the charge pump power supply, be careful of PVCC1 for applications or high switching frequencies with low VCC power voltage. The charging pump becomes higher and the switch nodes are lowered by Q2. The G2 connection time becomes LTC3830 narrowing (95%typical value) when working at the maximum occupy ratio. If the input power supply rises, this situation may occur from a soft startup capacitor or input slow load transient voltage. If the G2 becomes so narrow on time, so that the exchange node cannot be completely pulled to the ground, the charge pump voltage may collapse or cannot be started, causing the external MOSFET excessive loss problem 1. This is likely to be MOSFETs that reduce the conversion rate of G2 and exchange nodes at low VCC voltage and high switching frequencies.

The solution includes:

Increase the soft startup capacitor to limit the time to limit the duty cycle

Use smaller MOSFET and lower gate capacitors (if possible) Shorten the G2 rise/drop time exchange node conversion rate

Use the external high -voltage power supply to power PVCC1. If there is any way to increase one external circuit to limit the duty cycle when PVCC1 is low, as shown in Figure 9b Show. If the charging pump is not running, the PVCC1 will be less than or equal to VCC, and the voltage at the soft starting pin is about (VCC/6+VBE). This is about 1.2V, VCC is 3.3V, which limits about 50%of the duty ratio and allows the charging pump to start. Once the PVCC1 rises to (VCC+VTQ3), the voltage at the softening foot rises, and the duty cycle limit is canceled. For applications with 5V or higher VIN power supply, PVCC2 can be associated with VIN if you use logic level MOSFET. PVCC1 can be powered by dual -charge pumps, as shown in the figure 9A. When Q1 is connected, the circuit provides 2VIN -VF to PVCC1.

shows the use of 12.3V to 12 V's typical application dual -charge pump generates PVCC1.