LX1664/64A and LX1665/65A are the design of a single -chip switch regulator to control IC. high. Short -circuit current restrictions without expensive current detection resistors. The current sensing mechanism may use PCB marks resistance or parasitic resistance main electromoter. LX1664A and LX1665A use sensors to reduce the threshold of the current fluid amplifier to obtain the best performance. For high -precision applications, A traditional induction resistance can be used for induction current. CPU core programmable synchronization rectifier driver. The main output can be adjusted from 1.3V to 3.5V, and 5 -digit code is used. IC can read video signals

CPU core 5 -bit programmable output

Supply

can adjust linear regulator drive output

Short circuit restrictions do not need Sensor

Design for driving synchronization or

Non -synchronous output level

Soft startup capability

modulation, constant shutdown time architecture

[

123] Quick transient response and simplicity

System design

Overvoltage protection (OVP)

Tournament driver and power good flag (only LX1665)

socket 7 (Pentium class) microprocessor

Supply (including Intel Pentium processor,

AMD-K6TM and Cyrix #174; 6X86TM, GX86TM, M2TM processor) [123) [123) ]

Pentium II and Deschutes processors and L2-

cache supply

voltage regulator module

minimum packaging size. LX1664 is a installation IC packaging for the 16 -pin surface of narrow body for spatial sensitive applications. LX1665 provides additional overvoltage protection (OVP) functions and good power (PWRGD) output drives for application monitoring and protection functions that need output voltage. Ultra -fast transient response reduced system costs. The confinement time structure of the modulation to make the transmission response of the given sensor fastest, reduce the requirements of the output capacitor, and reduce the total cost of the regulator system. Overvoltage protection and good power flags. OVP output amp; AMP; LX1665A in LX1665 can be used for short -circuit events of the pry rod circuit owner of the derivative of the derivative of thyristor. LX1665 and LX1665A also have good logic levels. When the voltage exceeds the prescribed value

, the vast value value

Power voltage (VC1) 25 volts

Power voltage (VCC) 15 volts

Output drive peak current source (500ns) 1.5 amp

Output drive peak current absorption (500ns) 1.5 amp

Input voltage (SS, INV, VCC_CORE, CT, Video 0-VID4) -0.3 volt to 6 volts

Working temperature

Plastic (n, d, and dw packaging) 150 150 Celsius

Storage temperature range -65 ° C to+150 ° C

Lead temperature (welding, 10 seconds) 300 degrees Celsius

Note 1. More than these rated values u200bu200bmay may be Damage equipment. All voltages are grounded. The current of the specified terminal is positive input and negative output. The numeric numerals only refer to the DIL package

n (16 -pin DIP) packaging: environmental heat resistance, θJa 65 ° C/w

n (18 -pin DIP) package: environmental heat resistance, knot of environmental heat resistance, θja 60 ° C/W

D package: environmental heat resistance, θja 120 ° C/w

dw package: environmental heat resistance, θja 90 ° C/w

[ 123] Calculation of knot temperature: TJ u003d TA+(pd xθja).

θja is a guide to the thermal performance of the equipment/PC board system.以上都假设没有环境气流

电气特性

（除非另有规定，10.8 lt;VCC lt;13.2，0°C≤TA≤70°C。测试条件：VCCu003d12V， T u003d 25 ° C. Use application circuit.)

Note: In order to improve the transient response, one of the adaptive transient voltage output, one The 40 millivoltter offset is built into the current detection comparator. At high current, the peak output voltage is lower than the nominal set value, as shown in Figure 1. The actual output voltage is the function of sensing resistance, output current and output ripples.

Integrated circuit operation

Reference box diagram and typical application circuit

Output open the top MOSFET, allowing the increase in inductor current. At the error comparison threshold, the PWM locks are reset, the top MOSFET is closed, and the mosFet is opened. CT time capacitance CT is now okay. Under the Valley voltage, the MOSFET is cut off MOSFET. Special first -off and then combined circuits can prevent two MOSFETs from transmitting at the same time. VCC U core lending+40MV to enhance the transient response. INV pins are connected to the current influenza resistance, so the controller regulates the positive sensory resistanceEssence Under the light load, the output voltage is that the regulating voltage is higher than that of the nominal set value voltage. In the case of heavy load, the output voltage will be reduced to below the nominal set value voltage. As the output voltage changes and the frequency changes, the closing time is modulated according to the voltage at the VCC U core.

Error voltage comparator

Error voltage comparator comparative voltage sensor resistance side setting voltage plus 40 millivolves. External high -frequency noise is recommended to use filters.

current limit

The current limit is achieved by sensor current. The output driver is turned off by the current detection threshold and locks it until the PWM lock setting input becomes high again. See the current data behind the ""LX1664/65 Equipment"" behind this data.

Non -timed control timing

timing capacitor CT allows programming to close the time. This timing capacitor quickly charges MOSFET when connecting at the top, allowing discharge when the MOSFET is closed at the top. In order to provide a different power supply voltage, the discharge current is modulated from the VCC U core pin from the voltage. Close time and VCC U core voltage.

Obscashed lock

The purpose of UVLO is to keep the output drive off until the input voltage reaches the starting threshold. The voltage is lower than the starting voltage, the UVLO comparator disables the internal bias, and the output drive is turned off. SS (soft start) pins are low.

Synchronous control

The synchronous control part contains a unique first break -up function to ensure that the main switch and the synchronous switch are not connected at the same time. The disconnected circuit can provide about 100 nan seconds to protect the MOSFET switch.

Output voltage programming

The output voltage is set to identify (VID) by 5 digital voltage (see Table 1). The VID code can be hardly connected to the code -packet without VID, and the output voltage can be switched or skyrocketing through the DIP. For low or ""0"" signals, connect VID pins to ground (DIP open); for high signals or ""1"" signals, keep the VID pin open (DIP shutdown). The five VID pin design on the LX166X series is used to directly use the Pentium Pro or Pentium II processor. Therefore, all inputs should be ground or floating. Any floating object input will be raised by the interior. If you use the socket 7 processor or other loads, the VID code can directly set the jumper or DIP switch to the VID [0: 4] pin. The VID tube foot is not used to receive TTL inputs and should not be connected. Unpredictable output voltage may have results. If the LX166X device is connected to the logic of the logic for output voltage programming, such as BIOS should use the CMOS door with a leakage, such as 74HC125 or 74C906. Good power signal (Only LX1665) The output of the turbide set. When the output voltage is a programming VID voltage, measure at the SS pin. The impedance of the output window outside is very low. During the OVP operation, Power Good (good power) function will also be switched to LOW (low).

Overvoltage protection

Due to its constant shutdown time structure, the controller is inherently protected by overvoltage. However, the power switch fails, the driver's pin is provided (only LX1665), which can drive the external SCR crowbar (Q3), and then burn the fuse (F1). (See Figure 9).

Linear regulator

Product Highlight app displayed the application diagram using MOSFET as a stamina for linear regulators. This output is suitable for converting the 5V system power supply to a 3.3V processor I/O buffer, memory, chipset and other components. This output can adjust any voltage between 1.5V and 3.6V inch to provide other (lower) power requirements for the mother board. See the data table of the ""LX1664/1665 Equipment"" at the end.

LX1664/65 The device is very easy to design, and only a few simple calculations are required to achieve a given design. This procedure and precautions should provide effective operations for almost all applications. Refer to the ""Application Information"" section to understand the component reference code.

timing capacitor

Selecting LX166X's working frequency is the function cycle and closing time of the work. The closing time is proportional to the time -consuming capacitor (displayed as the data table in all applications in all applications), and the minimum frequency changes with the minimum frequency. The frequency is constant, running in a steady -state, due to the confinement of the confinement time. Timing capacitors (CT) should use the following formula:

fixed at 200 μFS is the switching frequency (it is recommended to optimize operating components at about 200kHz).

When using 5V input voltage, the switching frequency (FS) can be approximately as follows:

Selecting 680pf capacitors will cause operation. When the frequency is 183kHz, and the voltage is 2.8V, the electrical capacity must be changed (the best time-time-time-time-time-input capacitor should be within the range of 1000-1500pf). The inductance value selected by the L1 output sensor determines that the ripple current appears at the power output end. Determine the inductance size to allow nominal ± 10%to swing higher than and below the nominal DC power load current, use formula L u003d vl* #8710; T/ #8710; I, where #8710; t is the turnover time, VL is the voltage on the induction of the induction time, #8710; i is the peak ripple current in the inductor. It is necessary to choose a DC current of high -frequency magnetic core materials that can be processed, such as 3C8, which is suitable for the correct power level. The typical inductance range is 2 to 10 μH. Note that the ripple current will increase as the inductance decreases. The ripple current beyond the capacity of the capacitor may cause reliability problems.

Input sensor select

In order to cope with faster transient load changes, a smaller output inductor is required. However, reducing the output sensor will generate higher ripple voltage supply at the input terminal. The noise on the 5V guide will affect other loads, such as graphics cards. It is recommended to use a smaller input induction sensor. L2 (1-1.5 μH) is used for 5V guide to filter off the ripple. Make sure the rated current of this induction is the same sensor as the output.

C1 filter capacitor selection

The capacitors at the output end of the PWM part of the output terminal are used for filter output current ripples and helping the transition load conditions. Essence When the load current changes in the instantaneous (step) load current, the steps of the output voltage are equal to the volume -connected capacitor (ESR) and the current level leap ( #8710; i). When the current increases from low (sleep mode) to high output voltage, the output voltage will be lower than its stable state value. In advanced microprocessor power, the capacitor should usually be selected according to its ESR value, rather than a capacitor or a variety of square root current capabilities. Meeting the ability to meet the demand for electric slag melting usually has large capacitors and current applications required. The allowed ESR can: ESR*(Iriple+ #8710; i) lt; VEX where VEX is a ripple current for transient and rainbow. Like the LX166X series, the regulators have an adaptive output voltage positioning function. Therefore, increase the dynamic voltage allowed by the difference between the difference between the difference between the low load voltage between the low load and minimum voltage to the DC setting point voltage. The ripple current is a function of the output inductance value (LOUT). The approximation value is as follows:

Among the FS is the switching frequency.

The electrolytic capacitor can be used to output the filter capacitor group, but its stability is not as good as the capacitor. As their aging, ESR decreases, reducing the risk of failure to increase system performance. It is recommended that the use of multiple parallel containers so that as the age increases, ESR increases, and the overall performance can still meet the requirements of the processor. There are often strong stress requirements to use the cheapest, but this may lead to a decline in long -term reliability, especially in the case of filter capacitors. Lin Co., Ltd. Demonstration board uses Sanyo MV-GX filter capacitor C1 filter capacitor selection (continued) aluminum electrolyte, and has proven reliability. This OSCON series from SanyoIt is usually the best long -term ESR stability and general performance reliability, but the cost is huge. The MV-GX series provides excellent ESR performance to meet all Intel transient specifications and reasonable prices. Be careful, very low -cost filter capacitor, which has proven to change over time in these two ESR and general electrolyte characteristics.

current limitation

When the respondant voltage and load current, exceed the current detection comparator threshold values. The current can sensorize the parasitic resistance of the voltage of the voltage to the inductive voltage sensor with a capacitor and an inductive voltage sensor by using a fixed sensor to sensor the voltage of the inductor. The LX166X series provides two different comparative thresholds. The threshold of LX1664 and 1665 is 100 millivolttile, while the threshold of LX1664A is 100 millival LX1665A is 60 millivolttile. The 60 millivolo threshold is more suitable for higher current loads, such as Pentium II or showing processor.

current detection resistance

current detection resistor, R1, according to the formula: R1 u003d vtrip/itRip, where VTRIP is the current detection comparator threshold (100MV for LX1664/65, for LX1664A/65A/65A ) And itRip is an ideal current limit. Typical choices are shown below.

The resistance R decreases, the heat dissipation is reduced at a higher current, and the output voltage decreases less. There are several different types of sensors. The advantage of this surface -installed metal ""nail"" deformal resistor is that it is exposed to the free air, and its value can be controlled very strictly. However, its main disadvantage is cost. Another method is to use copper PCB to build sensing resistance tracking. Although the resistance can not be controlled so strictly that the PCB tracking cost is very low

current limit (continued)

PCB sensor resistor

The structure of the PCB sensing resistance is shown in the figure. As shown in the figure 10 Directly connect to the capacitor and sensor, and the larger copper effectively heat dissipates. As shown in the figure, the connection current detection line is avoided to avoid any errors.

The recommended induction resistor size as shown below:

Use the inductive resistance to achieve a lossless current sensing sensing sensing sensing. Any sensor has a parasitic resistance RL, which will cause the voltage drop when the DC current flows over the inductor. Figure 11 shows the sensor circuit, capacitors, CS, and inductors composed of the surface sticker RS u200bu200bRS RS, eliminating the current response resistor.

current limit (continued)

The current of the inductor is a triangular wave. If the selection of the sensor component should be ensured: left/right u003d the voltage on the rupee*CS capacitor is equal to the current flowOut resistor, that is,.VCS u003d ILRL reflects the sensor current because VCS reflects the sensor current. By selecting the appropriate RS and CS, the VCS can reach the comparator voltage (LX166XA is 60 millival, and LX166X is 100 millivoltturium) expected to check out.Design examples (Pentium II circuits, maximum static current 14.2A) sensors can be described as:

The hanging of the inductance.Test circuit (Figure 6) uses the following parameters: left behind u003d 3m #8486;, the rupee u003d 9K #8486;, carbon steel u003d 0.1 μF, 0A current L is 2.5 μH.