1 IR2161 main feature
IR2161 is the international rectifier company (IR) specially the intelligent control integrated circuit which designs for the electronic transformer. This component can actuate the low pressure halogen lamp. IR2161 needs the function complete collection in sole 8 pin DIP or in the SOIC seal, thus may reduce the part quantity, the simplified circuit effectively and strengthens the reliability.
IR2161 can adapt the voltage which, the frequency and the tube condition changes unceasingly, this characteristic is helpful to the design when introduces the highly reliable halogen transformer, simultaneously may simplify the design and the process of manufacture.
This section of compact 8 pin component provides IR the strengthened high pressure integrated circuit technology, simultaneously kneaded together the 600V half bridge driver, the advanced overload and the short circuit protection circuit as well as the high temperature closure and the adaptive control technology, may become except the tradition based on from resonant, outside bipolar transistor half bridge electric circuit plan another reliable choice. In addition, IR2161 content take bidirectional thyristor as foundation standard phase shifting light modulator, thus exterior can support adjusts the light. Compares other to use discrete component’s similar electric circuit, IR2161 can save 20% modules. The auto-adapted dead time control is also the IR2161 essential performance, may through continue the soft switch to strengthen transformer’s reliability. IR2161 ties take the IR high pressure isolates 煟 decayed tooth Zheng Shengsang the integrated circuit technology as a foundation. This patented technology separates the high tension circuit from the low tension circuit, Gao Ce and low side actuation function fusion in compact single chip, thus controls many kinds of switch switch’s analysis situs. Because the halogen illumination must coordinate the high pressure, the low tension circuit to be able to operate, therefore, based on IR HVJI technology component especially qualify this kind of application.
IR2161 other characteristics include: the 250/400mA output actuation capacity, 15.6V zener diode clamp Vcc, are lower than 300μA micropower starting and 30kHz~125kHz built-in oscillator and so on.
2 pin functions
Shown in Figure 1 is ZR2161 pin arrangement 煟 Sang Yaobo guarantees bites the barium pouch foot function like table 1 to arrange in order.
Table 1 IR2161 pin function
| Serial number | Mark |
Functional description |
| 1 | VCC | Low side logic and driving circuit’s supply voltage |
| 2 | COM | Integrated circuit’s power carries and the signal carries |
| 3 | CSD | Turn-off time control and compensation electric capacity |
| 4 | CS | Electroresponse input end |
| 5 | LO | The low side grid actuates the output |
| 6 | VS | High side fluctuation power source’s returns end |
| 7 | HO | Gao Cezha actuates the output |
| 8 | VB | Gao Cezha actuates to float the spatial power source |
3 IR2161 constitution electronic transformer
Shown in Figure 2 is uses the electronic transformer electric circuit which IR2161 constitutes. After the electric circuit starts the effective work, electric circuit’s subtracts through resistance RS on electric current by the IR2161 absorption starting current is given the electric capacity CVCC charge. The resistance size’s selection principle is guaranteed that it can cause the IR2161 normal work from the direct-current main line voltage gain enough electric current. Because the electric circuit can only in a half cycle to the CVCC charge, therefore selects time CVCC, must guarantee that VCC is higher than the undervoltage blockade threshold value in the other half cycle, will otherwise interfere with the entire electric circuit’s normal work. If merely through RS to internal circuit power supply, then the RS value cannot be oversized, otherwise cannot provide the electric current which the chip interior needs, meanwhile must consume 1W~2W the power loss. Might solve this problem through the electric charge pump electric circuit, in the chart has been composed an electric charge pump electric circuit by DCP1 and DCP2, this electric circuit and CSNUB carried on the connection to be possible to provide the electric charge which to VCC the internal circuit needed, because RS only time start had an effect, therefore, the RS value might take the big spot suitably, but will not affect electric circuit’s power loss.
Because 16V the zener diode VZ power loss reaches as high as 1.3W, therefore, Figure 2 in the electric circuit its external connection, reduces the chip the internal power loss. Thus, when has the big electric current appears, VZ may to the unnecessary electric current carry on the bypass, reduces to IR2161 the harm. In the electric circuit on a bidirectional thyristor’s strong voltage change can form big electric current, when it winds through resistance RD and electric capacity CD may charge immediately electric capacity CVCC the maximum value. Once VCC surpasses its start threshold value, HO and LO will start to vibrate, thus makes IR2161 to start the normal work. In the electric circuit RS, RD and the CD choice should guarantee when ballast normal work can provide the enough electric current. From lifts diode DB and the electric capacity CB function is provides the supply voltage to the high side power tube. In order to guarantee before the first pulse arrives at HO, the high side supply voltage already surpassed the undervoltage threshold value, the output actuation first pulse should send in the LO end. After LO passes through vibrated several times, if VB-VS surpasses the undervoltage threshold value, the high side driver will start to work. Under the undervoltage blockade pattern, the height side actuation outputs HO and LO is the low level.
Figure 2
4 auto-adapted dead times
The auto-adapted dead time control is the IR2161 essential performance, may through continue the soft switch to strengthen transformer’s reliability. The IR2161 equipment has a dynamic dead time electric circuit, when in half bridge structure direct-current bus bar loss of voltage to the 0V switch point, this electric circuit’s monitor function electric circuit can raise the low side driver (the LO output). When LO changes is low, its built-in sample and maintains has approximately the same detention, thus may after LO transfers lowly (the HO output) raises the high side driver. The auto-adapted dead time control may make the response according to the oscillator cycle, and may when the need adjusts the dead time.
When designer does not need to consider power tube’s parasitic capacity or output transformer’s leakage. In order to satisfy the electronic transformer power tube parasitic capacity and the output transformer leakage need, overall system’s smallest dead time establishment is 300ns.
Adds a cushion electric capacity on this electric circuit’s primary transformer to be possible to raise the slewing rate. But if the cushion electric capacity is oversized, also will prevent the VS voltage to the reversed direction change, will thus cause the dead time control expiration. The IR2161 default dead time is 1.2μs~1.4μs. The cushion electric capacity’s typical value is several hundred pF.
