Sichuan Tuwei ca-is3105w fully integrated DC-DC converter

One 、 Basic parameters

1

Integrated and efficient DC-DC Converter and on-chip transformer
 

- Built in soft start circuit to prevent surge current and output overshoot

- Overload and short circuit protection function

- Overheating shutdown protection function

2

Input voltage range ：4.5 V ~ 5.5 V

3

Output voltage optional ：
 

-3.3V、 5.0V、 3.7V、 5.4V

- Support connection at the output terminal LDO

4

Typical output power ：650mW(5V/130mA)
 

5

Temperature range ：-40 °C ~ 125 °C

6

Excellent isolation performance ：
 

- the height is 5 kVRMS Isolation voltage

- Surge ：10KVpk

- high CMTI：±150 kV/µS（ A typical ）

- Barrier life ：>40 year

7

Package form ：SOIC16-WB

Two 、 working principle

The feedback system feeds back the output voltage to the control system on the secondary side , produce PWM The signal ,PWM adopt OOK The modulation transmits the digital control signal to the primary side , The original side will PWM The signal is sent to the driver , Control the on-off of the primary power device , Energy flows from the primary side to the secondary side , Thus, the output signal is stabilized at the preset value .

as everyone knows , Switching power supply has several basic modules , Power device module （MOSFET,BJT etc. ）、 Magnetic components （ inductance , Transformer, etc ）、 control unit 、 Driver module ( Drive the power tube on and off ). As can be seen from the above figure ,CA-IS3105W There are power modules on the primary and secondary sides , Therefore, there must be drive units on both sides . The power modules on both sides are isolated by transformers . The on-off of the power devices on both sides continuously sends the energy of the primary side to the secondary side . commonly DCDC The power device has been , The drive control is integrated , There are not many transformers integrated on chip .

CA-IS3105W The micro transformer is integrated on the on-chip substrate .

therefore CA-IS3105W It is a highly integrated product .

3、 ... and 、 Product performance

 

Soft start

Soft start can effectively prevent the input current from flowing into , Ensure the safe operation of the whole power supply system .

The following figure shows the soft start waveform , The whole start-up process is roughly divided into three stages ：

The input voltage has not reached the original side UVLO, The chip doesn't work at this time .

When the input signal reaches UVLO, But the secondary side has not been reached , At this time, the secondary side voltage climbs slowly in steps .

When the secondary side voltage reaches UVLO when , The control circuit starts working , The control loop takes over the whole control system , The output voltage climbs rapidly , Until the preset value is reached .

 

 

Output short circuit protection

The working mechanism of short-circuit protection is roughly as follows ： When it is detected that the output voltage is lower than the short-circuit threshold , The chip stops working .

wait for 4ms after , The chip attempts to restart .

If in 1ms The output voltage does not reach the predetermined voltage within the time , At this time, the system determines that the short circuit exists , The protection mechanism continues to work .

If in 1ms The output reaches the predetermined voltage in time , At this time, the system determines that the short circuit is relieved .

 

Output voltage 4 File optional

By configuring SEL The pin can output 4 Output voltage ：

5.4V/3.7V The output voltage is LDO Provide input voltage , Provide low-noise power supply for the rear chip .

matters needing attention ：

1> Before the chip starts , Set the output voltage first , namely SEL The pins are well configured .

2>SEL The pin should not be suspended .

3> While the chip is working , Dynamic changes are not recommended VISO Output voltage .

 

Dynamic response

from 10% To 100% Under dynamic load, the output voltage overshoot and drop value are only more than ten mV.

 

Conversion efficiency

The efficiency curve is shown in the figure , The maximum efficiency under full load is 54%
 

 

PCB Design considerations
 

1>    In the input VINP And the output VISO Place at least 10μF capacitance
 

2>    The input and output capacitors are placed close to the chip pins , distance <2mm

3>    Add... In the middle layer VINP,VISO Copper foil to increase parasitic capacitance

4>    GNDP,GNDS Overlap capacitors to improve EMI

5>    GNDP and GNDS Pay attention to the creepage distance between copper foils , spacing >8mm

6>    Power plane construction edge protection

 

Four 、 Application scenarios

PLC application

CA-IS3105W To isolate the power supply , It can supply power to various isolators .

stay PLC in , Various digital isolators are used , For example, Sichuan soil CA-IS37XX、CA-IS36XX etc. .

BMS application
 

BMS Isolation is used in CAN And isolation I2C, The isolated power supply is matched with CA-IS305X Series of products , Form an isolation CAN programme .
 

Chuantu also provides integrated isolated power supply CAN Interface chip CA-IS3062W.

 

Photovoltaic inverter applications

Isolation is used in photovoltaic inverter 485/422, Isolated current amplifier .CA-IS3105W Provide energy for these isolation products .