SERVICE HOTLINE:86-769-85708313

With low power consumption standby and the function of PFC switching power supply controller

Issuing time:2020-07-24 21:51

Abstract: TDA16846-2 and TDA16847-2 is Infineon production improvement type switching power supply ( SMPS ) controller chip. This paper introduces the main characteristics, introduced with emphasis based on the TDA16846-2 color TV SMPS circuit work principle.

Key words: SMPS; TDA168460-2 / TDA16847; PFC controller;

1 Overview

Infineon Technologies ( Infineon ) launched the TDA16846 and TDA16847 switching power supply controller since put on the market, in the TV, VCR, SAT receiver and PC monitor SMPS has gained wide application. At present the two controller was improved, and the improvement and innovation of the device known as the type 2 or second generation products, the models were TDA168462 and TDA168472.

TDA168462 / TDA168472 is supported by low power standby and power factor correction and PFC SMPS controller, which can be used for the fixed frequency PFC or synchronous mode flyback converter, the product not only can drive the power MOSFET, also can drive the bipolar power devices. TDA168462 / TDA168472 at light loads with low power consumption performance, the switching frequency can vary with load loss and reduce stage by stage.

2 TDA168462 / 472 structure characteristics

TDA168462 and TDA168472 using 14 foot PDIP143 package, the pins are arranged as shown in figure 1. Figure 2 is the two chip to the internal structure of.

The two device is different TDA168462 8 feet did not answer, but TDA168472 8 feet for transient high power circuit power output management ( the foot through a capacitor and a RC circuit connected with ground ). The two pin of the device functions as shown in table 1.

Table 1 pin function

Lead foot character number power energy

1 OTC built-in cut-off time circuit, connected between the foot and the ground RC circuit, decided to ringing suppression time and standby frequency

2 PCS primary current simulation ( testing )

3 RZ1 adjustment and zero crossing signal input

4 SRC connected soft start and control voltage regulating capacitor

5 OC1 optical coupler input

6 FC2 connection (TDA16846-2 ) / the pin voltage is greater than 1, 2V, SMPS cutoff )

7 SYN synchronization input

8 N.C / PMO connection (TDA16846-2 ) / transient high power output circuit power management ( TDA16847-2 )

9 REF reference voltage and current

10 FC1 1 fault comparator input ( the pin voltage is greater than 1V, SMPS cutoff )

11 PVC primary voltage detection

12 GND

13 OUT MOSFET gate driver output

14 VCC supply voltage

TDA168462 / TDA168472 except with soft start, low power consumption, low starting current and voltage and overvoltage protection, current limit / short circuit protection and electrostatic discharge and ESD protection function, also has the following main features:

With the PFC, and the use of a charge pump circuit;

The frequency varies with load loss can be successively lower, in the standby mode, the frequency can be adjusted to 20kHz;

It can be at a fixed frequency or synchronous mode operation;

With the temporary high power circuit ( THPC ), with power management function (only TDA168472 ).

TDA168462 / TDA168472 5 feet ( OCI ) input voltage range is expanded to 0V, the foot and the ground connection resistance between no longer needed; 7 feet ( SYN ) to improve the startup characteristic, prevent transformer saturation; 11 feet ( PVC ) by adding a peak signal blanking, improves the anti noise ability; 13 feet ( OUT ) reduces the cutoff state output voltage level; 14 feet ( VCC ) by a spike blanking, improves the anti-noise performance.

With the previous TDA16846 / TDA16847 comparison, TDA168462 and TDA168472 except farther aggrandizement low power standby function, also can improve the anti-noise performance.

TDA168462 / TDA168472 support low power standby function, in a color television system is of great significance in the. The United States" Energy Star" and other standards TV standby power is less than 3W, according to center of Chinese energy-saving product certification and CPCE sampling investigation, homebred color television standby power consumption is lower than 3W accounted for only 13.4% of the total measured color television, and 9W above is occupied however 34.8%. The standby power consumption less than 3W of homebred color television series varieties have bigger increase, but from the full realization of less than 3W target to still have certain space. The use of TDA168462 / TDA168472 design of color TV SMPS can meet the requirements of low standby power consumption, and can reduce the cost of.

3 application circuit and working principle

With TDA168462 as controller of the SMPS circuit as shown in figure 3. For the implementation of PFC, the circuit in the bridge rectifier and 150 u F filter capacitor C07 is inserted between the by the inductance L08, diode D08 and capacitor C08 consisting of a charge pump circuit, so with the power switch ( T01 ), can be in the bridge rectifier input produced close to the sine wave of the AC current, and the AC line voltage close to the same phase, thus the circuit power factor ( PF ) is far greater than 0.90, total harmonic distortion ( THD ) of less than 20%.

3.1 starting characteristics

SMPS power, because the filter capacitor C07 anode DC mains voltage, so with the IC1 2 foot connected resistor R22 will pass current. The current from the IC1 2 foot by 2 foot into, with the 14 foot internally connected to the diode and see Figure 2 to 14 feet external capacitor C26 charging. Once the C26 charging voltage reaches 15 + 0.5V conduction level above, the chip to start work. Device 14 feet Vcc conduction current typical values for 5mA, through the C26 discharge to 14 feet to the voltage drop, in yet to undervoltage shutdown threshold, the auxiliary winding of the transformer ( 7T ) through the IC14 foot external diode chip D26 to provide the desired current. When IC at fixed frequency operation, in order to prevent initiation during multiple pulses, in IC1 3 foot pulse voltage exceeds the 2.5V threshold before, make IC1 work to free oscillation ( free running ) mode.

3.2 primary current simulation / current limit

Circuit of IC1 2 foot external resistor R22 and a capacitor C22 is used to generate a power transistor T01 current proportional to the voltage. In the T01 at the end of 2, feet on voltage of 1.5V, such as C22 through R22 is charged, T01 will be in the state of conduction. At this point the voltage on the V2 pin 2 can be expressed as:

V2 = IP / ( R22 C22 ) 1.5VLP

In the formula, LP is the transformer primary winding inductance, IP through the power transistor current.

V2 is generally applied to the IC2 foot inside time comparator the non-inverting input end, and the inverting input terminal on a control voltage comparison. If V2 exceeds the control voltage, the drive block, to current limit function. The control voltage is the maximum value is IC1 within the 5V reference voltage. Power transistor IP ( max ) for maximum current:

IP ( max ) = [ ( 5V1.5V ) R22 C22] / LP

The control voltage can be made by IC1 within the error amplifier, optical coupler or the voltage on the IC1 pin 11 ( V11 ) to decide.

The 3.3 retrace ( Fold Back ) point correction

The IC1 pin 11 ( PVC ) of the voltage V11 from the connection to the DC bus and between the resistor divider ( R23 and R24 ) access. If the rectified bus voltage increases, the maximum current IP power transistor ( max ) will be reduced. In fact, the maximum current IP ( max ) is an independent, and the DC bus voltage. Can be expressed as:

Ip ( max ) = [ ( 4VV11 / 3 ) R22 C22] / Lp

3.4 deadline circuit and OTC

The IC1 pin 1 ( OTC ) external and connection between R30 and C30 for RC parallel network. When the IC1 driver is turned off, the internal current source the first 0.5mA current on foot 1 external capacitor C30 charging. Once the pin is 3 ( RZI ) on the voltage reaches 2.5V, the charging current to reach 1mA, until the C30 voltage is charged until 3.5V. The charging time of C30 about R = ( C30 * 1.5V ) / 1mA.

When the C30 voltage reaches 3.5V, the internal current source will be cut off, C30 discharge through R30. When the IC1 pin 1 voltage is applied to the internal cut-off time comparator, another input of the comparator is a control voltage. When the cut-off time comparator outputs high level and 3 feet on a voltage less than 25mV, internal conduction time trigger position, to ensure that the power transistor in the minimum voltage switching. If there is no zero crossing signal into IC1 foot 3, then, at the foot of 1 on a voltage less than 1.5V, power transistor will pass after a period of time delay switch. As long as the foot 1 voltage is higher than the restricted control voltage, conduction time trigger will stop, to suppress the foot 3 inappropriate zero crossing signal. Once the control voltage is lower than 2V, shutdown time to reach a constant maximum value ( ~ 0.56 R30 C30 ). Table 2 lists the control voltage and the output power and the cut-off time relationship.

Table 2 control voltage and output power, the cut-off time relationship

Control voltage output power cut-off time

1.5 ~ 2V low constant ( maximum )

In 2 ~ 3.5V decreases

3.5 ~ 5V high free oscillation

In fact, switching frequency is output function.

TDA168462 load dependent frequency curve as shown in figure 4.

The 3.5 error amplifier / soft start

IC1 ( RZI ) 3 feet is the error amplifier and the zero-crossing signal input, ( SRC ) the 4 foot is a control voltage input. The error amplifier non-inverting input end is 5V reference voltage. The IC1 pin 3 on the input signal can be obtained from the auxiliary winding of a transformer by R38 and R29 consisting of a resistive voltage divider to obtain. If the foot 3 input pulse is higher than the threshold 5V, pin 4 on the control voltage will be lower. Therefore, the foot 4 and is connected between the capacitor C25 can be used to determine the control voltage to control the speed and duration of soft start.

3.6 fixed frequency and synchronous operation

As shown in Figure 3, the application circuit, because the IC1 7 foot and the 9 foot ( 5V reference voltage output ) are connected together, so the IC1 work in free oscillation mode of regulation.

If you want IC1 in fixed frequency operation, pin 7 must be connected in parallel between the earth and the RC network ( Rosc and Cosc ), at this time, the switching frequency FSW by Rosc and Cosc set:

FSW ~ 1.2 / Rosc Cosc.

Therefore, when Rosc = 20K &, Cosc = 470pF, FSW = 88kHz.

To make IC1 work in the synchronous mode, pin 7 to add the synchronous signal frequency to be higher than the frequency of the oscillator.

TDA168472 application circuit and TDA168462 application circuit is compared, in addition to TDA168472 8 feet outside between the earth and the need to connect a 100pF capacitor and the RC and R = 1M & C = 4.7, F circuit, the other part is almost exactly the same

previous item: Programmable voltage monitoring watchdog timer resetnext item: Application and development of QS9000 standard

Share to:
Fax: 0769-85706977 Direct line: 0769-85700063   85704518 ADDRESS: LongYan Industrial Zone, HuMen Town,DongGuan City , GuangDong