Function description

LM5070 power interface port and pulse width is completely compatible with 802.3AF power interface port modulation (PWM) controller provides complete 80V, 1 , 400 mA internal MOSFET integrated solution, applicable In the programmable wave current restricted access to Ethernet power supply (POE) system. This detection resistance blocking function LM5070 integrates 80V and 400MA line connections to the programmable sorting of the switch with complete IEEE802.3AF and the related control controller. There are two options.

The programmable classification current compatible interface with a full-function current mode

A programmable under pressure lock, with a pulse wide adjustment DC-DC converter. All power

The heat clearance protection interface and switching power supply (SMPS) are integrated into the integrated circuit.

The vein width of the current mode pulse width provides 80%maximum duty cycle limit

supports isolation and non-isolation device with slope compensation (suffix-80) or

Application Compensation on the maximum duty cycle and non-sloping (-50 suffix) device.

Error amplifier and non-isolation benchmark

Application

Packaging

The frequency of programmable oscillator

TSSOP-16

[ 123] Programmable soft start

WSON-16 (5 mm x 5 mm)

80%maximum duty cycle limit limiter, slope

compensation (-80 device)

50%of the maximum duty cycle limit, no slope

compensation (-50 device)

800 mAh door driver

Electrical characteristics (1)

In TJ type, operation specifications above 25 ° C are suitable for the full cross section temperature range. Unless there are other regulations: vin u003d 48V, VCC u003d 10V, RT u003d 30.3K

(1) The minimum and maximum limit is performed under 25 ° C under 25 ° C. 100%production test. The statistical quality control (SQC) method within the working temperature range is specified through the correlation. Restricted to calculate the average shipment quality level (AOQL).

Electrical characteristics (1) (continued)

In TJ type, operation specifications above 25 ° C are suitable for the full section temperature range. Unless there are other regulations: vin u003d 48V, VCC u003d 10V, RT u003d 30.3K

123]

(2) Equipment heat limit may limit the available range.

(3) Specifications are suitable for the frequency of oscillator. The operating frequency of the LM5070-50 device is divided by 2.

Detailed operation instruction (PWM) The controller provides a complete integrated power supply device (PD) solution for the Ethernet power supply (POE) system. The PD interface part of the main characteristics of integrated circuits includes detection, classification, programmable wave surge current restrictions, heat restrictions, programming that can be lock -up, current restrictions monitoring. The high -voltage range switching voltage voltage supply also includes the control part of the high -voltage start -up switch integrated circuit includes good sensing, voltage locking VCC regulator, circulating current limit, error amplifier, slope compensation, soft startup, and synchronization with the oscillator. This high -speed BICMOS integrated circuit has a total transmission delay of less than 100NS, and a 1MHz oscillator is programmed by an external device. The LM5070 PWM controller is a single -drive output, such as rejuvenation and positive topology. LM5070 PWM controls the current mode control, including line feedback, circular current limit, and simplified loop compensation. The oscillator slope is added to the PWM comparator into the slope in the PWM comparator to provide the compensation required for the current mode control when the slope occupy the duty cycle (only-80 suffix).

Operation mode

LM5070 PD interface aims to provide completely compatible IEEE 802.3AF systems. Therefore, the mode operation considers that barrel -shaped rectifiers are usually used to correctly input cable TVs from Ethernet. Table 1 shows the working mode of the LM5070 and the related input voltage range.

When the vehicle recognition number (VIN) exceeds 1.8 volts, the external feature resistance is connected to the VEE to start the detection mode. In the period detection mode, the static current consumed by LM5070 is less than 10UA. The device enters the classification mode between 10.0V and 12.5V, and the feature resistance is disabled. The category range mode is 11.5V to 21.5V. Once the voltage of the grading range is exceeded, the classification current will be closed to reduce power consumption. Between 21.5V and UVLO, the device is in a standby state, waiting for the input voltage to reach the operating range to complete the power -on program. Once the VIN voltage increases higher than the upper-limit UVLO threshold voltage, the internal power MOSFET can charge the input capacitor to the DC-DC converter. When the MOSFET VDS voltage is lower than 1.5V, the internal power supply has a good signal to enable the SMPS controller. The input voltage of LM5070 is up to 75V. whenWhen VIN dropped to lower UVLO, the SMPS controller and internal MOSFET were banned.

Detection

In order to detect the potential power supply equipment, PSE will apply 2.8V to 10V voltage PD terminals on the input terminal. The voltage can be any polarity, so a diode network is required on both lines to ensure this ability. PSE will measure twice, at least 1V and 2ms. The voltage slope between this measuring point must not exceed 0.1V/US. Triangular voltage/triangular current is calculated and then executed; if the detected impedance is higher than 23.75k below 26.25k , PSE will consider PD. If the impedance is less than 15K or greater than 33K then it is considered that there is no PD and will not get energy. The impedance between these values u200bu200bmay indicate a effective local discharge, or it may not indicate. The LM5070 will use the feature resistor when the controller input voltage is 1.5V to consider the decrease of diode voltage. The offset voltage that PSE can withstand does not exceed 1.9V (caused by the external diode) or higher offset current (bias current) is greater than 10UA. The input capacitance must be greater than 0.05UF and less than 0.12. In order to improve efficiency, once the input voltage is disabled by the LM5070 controller, the signature resistance will be disabled higher than the detection range ( gt; 11V).

Classification

In order to classify local discharge, PSE will provide PD with a voltage between 14.5V and 20.5V. LM5070 makes the rated input voltage of 11.5V. The internal 1.5V linear regulator and the external resistor are connected to the RCLASS pin to provide a classified programming current. Table 2 shows the classification resistor required for external specific grades. Classified current flows into the classification resistor through IC. The recommended resistance value takes into account the bias current flowing into the integrated circuit. By dividing 1.5V, different expectations of RCLASS can be calculated according to the required classification current. According to the IEEE802.3AF specification, the classification is optional, if the classification current is not detected. If you do not need a PD classification (that is, level 0), you only need to leave the RCLASS to open it. According to IEEE 802.3AF, the duration of the classification period must not exceed 75ms. LM5070 will maintain a classification mode until the vehicle identification number (VIN) is greater than 22 volts.

IOU Lock (UVLO)

IEEE 802.3AF specifications, PSE will be detected. The LM5070 contains a programmable circuit that is underwritten (UVLO) circuit. The first resistor should be connected between the VIN and UVLO pins; the bottom resistor in the frequency division should be connected between UVLO and UVLORTN pins. The bottom resistance should not be connectedReceived Vee, because from the detection mode, VIN to VEE will cause the system to violate 10UA's maximum offset current specifications. The design of the sterilizer must ensure that when the vehicle recognition number (VIN) reaches the required value, the voltage at the UVLO pin is equal to the minimum working level of 2.0V. If the UVLO threshold is not reached, the interface control and SMPS control will remain on the spare item. The UVLO delay is completed by an internal 10UA current source, which is the impedance of the point assignor at the UVLO settings. When the UVLO threshold is exceeded, the current source is activated and immediately increases the voltage of the UVLO pin. When the UVLO pin voltage is lower than the 2.00V threshold, the current source is closed, causing the voltage of the UVLO pin to decrease. The LM5070 UVLO threshold cannot be programmed below 23V, otherwise the device will run in the classification mode, while the classification current source and SMPS have been enabled. The comprehensive power consumption of these two functions may exceed the maximum power consumption of packaging. There are many other uses of UVLO pins. It can also be used to implement the UVA function enable/disable function. Pull the UVLO pin down to the UVLO threshold and the SMPS controller will be disabled.

Power operation/current -limiting programming

Once the UVLO threshold is met, the interface controller of the LM5070 will charge SMPS to enter the capacitor through the internal power MOSFET. This load capacitor provides the input filter according to the IEEE802.3AF specification. The converter segment must be at least 5UF. In a control method, the current of power MOSFET is limited to 375mA. IEEE802.3AF specification requires that the load capacitance is charged within 75ms.

Some traditional PSE may not be able to provide PD with a maximum power of 15W, which may be a problem at startup. The low -power PDS used in these traditional systems requires a lower start -up current limit. The LM5070 can be programmed through the resistor at the RCLP pin to reduce the level of influxing current limit. This programmable wave current limit range is 75mA to 390mA. If the RCLP pin is kept open, the LM5070 will default to 390mA, close to the maximum value allowed by the IEEE 802.3 specification. Set the required wave current limit (limit), the RCLP resistor can be calculated based on the following formulas:

Before the load capacitor is fully charged, the SMPS controller will not start the operation. The order between the power interface circuit and the SMPS controller is automatically carried out in the LM5070. Detect the circuit monitoring RTN pin to detect the completion of the interface. When the RTN pin potential decreases, it is lower than 1.5V compared to VEE, and the VCC regulator of the SMPS controller is enabled. The soft startup function is enabled after the VCC regulator reaches the minimum operating voltage. RCLP programming's excitation surge limit value is only applicable to the initial charging stage. Interface power MOSFET current limitation will return to fixedOnce the default value is powered on and starts softly starts, the protection current is limited to 390mA.

High -voltage startup regulator

LM5070 contains an internal high -voltage startup regulator, allowing the connection input pin (VIN) to the line voltage up to 75V. The internal current of the regulator is limited to 15mA. The recommended capacitor range output by this VCC regulator is 0.1UF to 10UF. The voltage on the V CC pin reaches 7.8V regulatory nodes, and the controller output is enabled. The controller will keep it in the state until VCC is lower than 6.25V. In typical applications, the transformer auxiliary winding is connected to the VCC pin by diode. This winding should increase the VCC voltage to above 8.1V to close the internal startup regulator. Although it is not needed, the power supply winding for VCC has improved the conversion efficiency while reducing the power consumption of the controller. The external VCC capacitor must be selected to keep the VCC voltage of the capacitor be maintained at the drop threshold (6.25V) than the VCC UVLO reduction threshold (6.25V) during the initial startup period. When a torque assisted device fails, the winding is not active, and the external current on the VCC line shall be limited to the maximum power consumption capacity of the module that does not exceed the LM5070 component.

error amplifier

Internal high -gain error amplifier provided within LM5070. Set the fixed reference voltage of the non -rotation of the amplifier to 1.25V. Reverse input to FB pins. In non -isolated applications, the power converter output is connected to the FB pin through voltage scale resistors. The loop compensation component is connected between the COMP and the FB pin. For most isolation applications, the error amplifier function is implemented on the secondary side of the converter, and the internal error placed is not used. This internal error amplifier is configured to open the road leakage output, which can be connected to Arton by connecting the FB pin. The internal 5K pull -up resistor between the 5V reference voltage and the COMP can be used in optical coupling in isolation applications.

current limit/current influenza response

LM5070 provides a cycle -by -current over -current protection function. The current limits are compared with internal current influenza. If the voltage at the current influenza input CS exceeds 0.5V, for RTN/Artn, the output pulse will be terminated immediately. A small RC filter, located near the CS pin, is recommended to filter the noise of the controller. CS input has an internal MOSFET, discharge the CS pin capacitor at the end of each cycle. After the new cycle starts, the emission device is maintained with an additional 50 NS to attenuate the front edge peak -influenza response signal.

LM5070 current detection and PWM comparator are very fast, which may make response pulse on short -term noise. The layout is essential for current detection filters and detection resistors. When related capacitors use CS filters, the filter must be very close to the device and directly connect to the pin (CS) pin and Artn). IfWith the current fluoroscoper, the two leads on the secondary side of the transformer shall be wiring to sensor resistance and current influenza filter network. A sensor power MOSFET located in the primary power supply can be used for current sensing, but a low -induced resistor is required. When a current fluorine resistor is used, all noise -sensitive low -power grounding connections shall be connected to the local connection and large current source loop (sensing resistance) of the controller together).

The oscillator, shutdown and synchronization function

A single external resistor connected between RT and Artn pin sets the frequency of LM5070 oscillator. LM5070–50 device (50%duty duty limit option) has an oscillator that except two circuits. This difference is created by the two circuits to create a accurate 50%duty cycle, which is used to create an accurate 50%duty cycle limit function. Because this is divided by 2, the operating frequency of the internal oscillator is output (output). For the LM5070–80 device, the frequency of the oscillator is the same as the operating output frequency. To set the required output operating frequency (F), the RT resistance can be calculated based on the following formulas:

LM5070 can also be synchronized with the external clock. The frequency of the external clock must be higher than the self -excitement frequency of the RT resistance settings. The clock signal should be inserted into the RT pin with a 100PF capacitor with a capacitor coupling. The peak voltage level at the RT pin is required to detect the detection of the peak voltage level greater than the 3.7 volt synchronization pulse. Synchronous pulse width should be set up between 15 and 150ns. Regardless of whether the oscillator runs freely or external synchronization, RT resistance is required. The voltage at the RT pin is adjusted to 2 volts. The RT resistor should be located very close to the device and directly connected to the pin (RT and Artn) of the controller.

PWM comparator/slope compensation

PWM comparator outputs the current slope signal with the circuit error voltage generated by the error. The output voltage of the error amplifier at the compensation pins is 1.4V, and then further attenuates through a 3: 1 resistor compressor. The polarity of the PWM comparator enables the 0 volt voltage on the compensation pin to output the duty cycle of the zero controller. For a duty -occupying ratio greater than 50%, the current control circuit is affected by secondary resonance oscillation. This oscillation can be avoided by adding an additional fixed slope voltage slope signal (slope compensation) for current detection signals. The LM5070-80 integrated this slope compensation to add the current slope generated by the oscillator to the current slope with the current influenza response signal. The slope can be performed by increasing the source resistance of the current detection signal (the resistance between the external CS pin and the current fluorine resistor) can be used. Because the LM5070-50 cannot work more than 50%, this device has no slope compensation function.

Soft activation

Soft activation feature allows power converter to gradually reachTo the initial steady -state work point, thereby reducing the starting pressure, excessive output and current surge. When power is powered, the VCC is underked to meet the threshold after locking, and the internal 10 μA current source is charged to the external capacitor connected to the SS tube foot. The capacitor voltage will rise slowly and will restrict compensation pins voltage and output duty -occupying pulse.

The door drive and maximum duty cycle limit

LM5070 provides an internal grid drive (OUT), which can generate and absorb a peak current of 800 mA. This LM5070 has two types of duty duty limit options. The maximum output duty cycle is usually 80%LM5070-80 options, which is accurate equal to 50%of the LM5070-50 option. The maximum duty cycle function LM5070-50 is done by an internal trigger, which ensures that an accurate duty cycle is limited. Therefore, the internal oscillator frequency of the LM5070-50 is twice the operating frequency of the PWM controller (output pins). The maximum duty cycle limit of 80%of the LM5070-80 is determined by internal oscillator, and the variable range is larger than 50%of LM5070-50. For LM5070-80, the frequency of the internal oscillator is equal to the frequency of the PWM controller.

Heat Protection

Provides internal heat shutdown circuits to exceed the temperature at the maximum knot. This function can prevent disaster failure caused by overheating equipment. when? Activation (usually at 165 degrees Celsius), the controller enters low -power standby status, disables output drives, biased regulators, main connecting port MOSFET, classification regulator, if it is enabled. At a decrease in temperature (typical lag u003d 25 ° C), the VCC regulator will be enabled and the soft startup program starts.