Features

8V (DC) to 550V (DC) input voltage range

efficiency gt; 90%

#8226 ; Stable running at a duty cycle of more than 50%

series/parallel drive multiple LED

adjust LED current

# 8226; linear or PWM brightness control input

resistor programming minimum closure time

package that meets the SOIC-8 ROHS standard

#8226; Anti -voltage or boost configuration

Application

Tablet display RGB backlight

Sign and decorative LED lighting

[[

[[

[[

[[

[[

123] DC/DC or AC/DC LED driver application Instructions

CPC9909

is a low -cost, high efficiency, offline, high brightness ( HB) LED driver uses the IXYS integrated circuit department's high -voltage BCDMOS on Soi process. This driver has an internal regulator that allows it to work from 8V (DC) to 550V (DC). This wide input working voltage range enables the driver to be used for a wide range of HB LED applications.

CPC9909 has pulse frequency modulation (PFM) and constant peak current control scheme. This adjustment scheme is essentially stable, allowing the driver to run under the duty cycle of more than 50%without the open ring unstable or secondary resonance oscillation. LED lighting can be achieved by applying a small DC voltage on the LD pin, or by applying a low -frequency PWM signal to the PWMD pin.

CPC9909 has a standard 8 -lead SOIC packaging and a thermal enhancement 8 -lead SOIC packaging with a thermal heating pad (EP).

CPC9909 box diagram

Order information

function description

Figure 1 Typical application circuit

Overview

CPC9909 Drives the LED through the minimum turnover time, peak current limit, and pulse frequency modulation scheme. The control scheme is essentially stable, and the driver can work at a duty cycle of more than 50%without any open -loop instability or secondary resonance oscillation. Because the switching frequency depends on the LED load current, it can achieve high efficiencyWork.

The working principle of the LED drive

The typical application circuit is shown in Figure 1. When the PWMD is high -electricity, the control circuit is enabled, and the grid drive opens the external power MOSFET (Q1), resulting in the result The sensor (L1) current rises until the voltage on the current influenza resistor (RSENSE) exceeds VCS (high). When the voltage on the CS pin exceeds this threshold, the door drive is turned off Q1. Q1 Keep closed within the fixed minimum closing time. When the switch is cut off, the inductor continues to convey the current through the diode (D1). When the off -off time is over, the Q1 is turned on again until the peak current limit is reached, and the process is repeated.

The peak current limit threshold is set by the external sensing resistor RSENSE and the internal voltage threshold VCS (height). This internal voltage threshold can also be set through the LD pin. The lower value in these two thresholds and RSENSE set the peak current of the inductance.

The soft startup function can be achieved by increasing the DC voltage at the LD pin at the required rate from 0V to VCS (high). To use the soft startup function, connect the resistor separator from VDD to the ground, and connect the capacitor from the LD pin to the ground, as shown in it.

Figure 2 Soft startup circuit

Input voltage regulator

CPC9909 has an internal voltage regulator, which can be from 12VDC to 550VDC Work under the voltage. When a DC voltage greater than 12V is applied at the VIN pin, the internal voltage regulator lowers the voltage to the typical 7.8V. The VDD pin is the output pin of the internal voltage regulator. It must be bypass by a low ESR capacitor to provide a low impedance path for high -frequency opening noise.

The CPC9909 drive does not require the bulky start resistance that the offline controller is usually required. The internal voltage regulator provides sufficient voltage and current for internal IC circuits. This voltage can also be used for VDD pins and can be used as bias voltage for external circuits.

The external DC voltage that is slightly higher than the regulator voltage generated by the VDD pins can bypass the internal voltage regulator. This reduces the power consumption of integrated circuits, and is more suitable for the isolation application of the auxiliary wound drive VDD tube foot.

The total input current led from VIN pins is equal to the static current consumed by the internal circuit (maximum 0.6mA) plus the grid drive current. See the turnover mode power current .

The current consumption of the grid drive depends on the grid charge of the switching frequency and external power MOSFET. The total input current can be calculated through the following formulas:

Among them, QGate is the total grid charge of MOSFET, and FS is the external frequency of the oscillator.

ElectricityFlow detection resistor

The peak LED current is set by an external sensing resistor (RSENSE), which is connected from the CS pin to the ground.

The value of the current fluorine measurement resistance is calculated based on the average LED current, current influenza test threshold and inductor ripple current.

The peak-peak difference in the electrical sensor current waveform is called an inductor ripple current (usually the electrical sensor is large enough to keep the ripple within 30%of the average value). Calculate the ripple current coefficient when the sensing resistance.

The current detection resistance value can be found in the following ways:

In the formula:

vcs (high) current current Detection threshold 0.25V (or VLD)

ILED average LED/inductor current

△ IL inductance ripple current 0.3*ILED [123 [123 [123 ]

Combination term:

current detection and consumption

CPC9909 has an internal current detection and anti -hidden circuit. When the power MOSFET is turned on, the external inductor will cause peaks that do not want to occur at the foot of the current influenza, which will cause the grid pulse to end early. In order to avoid this situation, a typical 400NS intra -edge of the cutting -edge hidden time is used, thereby eliminating the needs of external RC filtering, and simplifying the design. During the current period of the current detection, the current limitation comparator is disabled to prevent the gate -drive circuit from terminating the grid drive signal.

Enable/disable function

Connect PWMD pins to VDD to enable the door drive. Connect PWMD to GND to set the disabled driver and set the device as a standby mode. In the standby state, the maximum static current is 0.6mA.

The shortest shutdown time once

CPC9909 uses a fixed closing time control solution. The minimum disconnection time is set by the external resistor connected between the RT and GND terminals.

The shutdown time can be determined by the following formulas:

The choice of closing time indirectly determines the switching frequency of the LED drive.

The frequency of the switch is determined by the following factors:

d occupy the duty

] TOFF Close time

Generally speaking, the choice of switching frequency is based on inductance size, controller power consumption, and input filter capacitance.

The typical offline LED driver switching frequency FS is between 30kHz and 120kHz.

The scope of work gives designers a reasonable compromise switch loss and inductance size. The accuracy of the internal shutdown time is ± 20%. The figure below shows the selection of RT resistor that needs to be closed.

inductor design

The inductor value is defined by the LED/inductive ripple current, minimum turning time, and output voltage. The minimum turnout time is determined by the duty duty ratio and the switch frequency. The duty cycle is concluded by the following formulas:

Among them:

vledstring is the LED string voltage under the average LED current required.

vin (min) is the minimum DC input voltage.

The minimum sensor value of the given line wave current is:

Current

The peak current of the inductor is obtained from the following:

CPC9909 Use the internal grid drive circuit to open it to open it And turn off the external power MOSFET. Gallery drivers can drive various MOSFETs. For typical offline applications, MOSFET's total grid charge will be less than 25nc.

Linear dimming

Linear lighting function can be achieved by applying DC control voltage to the LD foot. By changing this voltage from 0V to VCS, users can adjust the current level in the LED, thereby increasing or reducing the strength of the light. The control voltage of the LD pin can be generated from the external pressure network of the VDD. If the user needs a specific level of LED current and does not have an exact RT value available, this function is very useful. Note that due to the fixed internal threshold settings, the voltage of the LD pin higher than the current detection threshold voltage does not change the output current. When you do not use LD pin, you should connect it to VDD.

FIG. 3 Typical linear lighting application circuit

Lighting

pulse width modulation light adjustment can be used in hundreds of Hertz range Use low -frequency square wave signal to drive PWMD tube feet to achieve. The PWMD signal controls the brightness of LED by controlling the PWM door driver output pins. The signal can be generated by a microcontroller or pulse generator, and the duty cycle ratio is proportional to the required light output.

Figure 4 PWM Lighting Application Circuit's Anti -Pressure Drive

Portal and PWM Lighting

Line -in light adjustment and PWM adjustment The combination of optical technology can achieve a large lighting ratio.

All plastic packaging semiconductor packaging is easy to be wet. The Ixys Integrated Circuit Department conducted a wet-sensitivity classification of all plastic packaging devices based on the latest version of the joint industry standard IPC/Jedec J-STD-020 (effective in product assessment). Under the maximum conditions specified in this standard, we test all our products and ensure that our equipment can run normally when the restrictions and information in the standard and the information or the standard specified in the standard below.

Failure to abide by the warnings or restrictions specified in the specifications listed in the institute may lead to a reduction in product performance, shortening the operating life, and/or decreased overall reliability.

This product has the wet-sensitivity grade (MSL) shown below, and it should be processed in accordance with the requirements of the latest version of the joint industry standard IPC/JEDEC J-STD-033.

ESD sensitivity

This product is sensitive to static electricity, and should be processed in accordance with industry standards JESD-625.

Retroktop solder curve

The maximum body mild time rated value of this product is shown below. All other guidelines in J-STD-020 must be obeyed.

Washing board

IXYS Integrated Circuit Department's recommendation uses non -clean welded formula. However, it can be used to remove the residue by cleaning the board, and it may need to be baked with a short time. Do not use chloroblasts or fluoropic solvents or welds. The cleaning method of ultrasonic energy should not be used.

Mechanical size

1-1 8 stitch SOIC packaging

1-2 8 stitches SOIC EP package

Note: The hot pad should be connected with the GND pin 3 electricity.

1-3 Packaging Information

It is used for SOIC-8 and SOIC-8 EP packaging.

Note: The unwanted tape size conforms to the Jedec standard EIA-481-2.