In the field of electric vehicles and fast charging power supplies, CXSD62682 synchronous rectifier buck chips are becoming the first choice for highly integrated DC-DC conversion with a wide voltage input range of 20-100V and a built-in 100V power tube. This QFN32 packaged power management chip integrates power devices and intelligent control functions, greatly simplifying the design of high-voltage high-current systems.
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[ CXSD62682 ]"
CXSD62682: 100V integrated MOS buck scheme for innovative wide voltage input power supply design
In the field of electric vehicles and fast charging power sources,CXSD62682 synchronous rectifier buck chipWith a wide voltage input range of 20-100V and a built-in 100V power tube, it is becoming the first choice for highly integrated DC-DC conversion. This QFN32 packaged power management chip integrates power devices and intelligent control functions, greatly simplifying the design of high-voltage high-current systems.
1. Breakthrough Technology Features
1. Highly integrated design
a. Built-in100V/20mΩ power MOS tubeSupport continuous 6A output current
B. Dual start mode: VIN pin quick start (20-150V) or external resistor start (11-100V)
c. Integrated 5V reference source (VDD pin, ± 5% accuracy)
2. Intelligent control core
a. Adjustable switching frequency:FOSC (kHz) = 6150/RI(kΩ)(Typical 125KHz @ 47kΩ)
B. Programmable Dead Time:DT (NS) = 5 × RT(kΩ)(250-1000ns range)
c.190mV high precision cycle-by-cycle current limit (IS pin detection)
Multiple protection mechanisms
a. Output short-circuit latch protection (to avoid repeated restarts)
B .155 ℃ over-temperature shutdown protection
C. electric door lock closing delay function (T = 0.93 × C8 × R8Delay in seconds)
Analysis of 2. Typical Application Scheme
1. Electric vehicle converter design
(Figure 6-1) Using VIN direct start scheme, through FB resistor voltage division formulaVout =(1 R1/R2)× 1.3VRealize 12-48V regulated output, combined with the shutdown delay circuit to avoid the transient impact of the electric door lock.
2.PD fast charging power supply(Figure 6-4) Support PD3.0 protocol:
A. RI pin is connected to 82kΩ resistor to set 75KHz operating frequency
B. IS pin is configured with current limiting resistor (R3=0.19V/Ipeak）
c. Synchronous rectification efficiency> 92% (measured data)
3. Industrial power system
a. Continuous mode inductance calculation:L = Vout(Vin-Vout)/(Wine · Fs · Iripple)
(ripple current ≤ 30% full load)
B. Output capacitor selection formula:& Delta;Vo = & Delta;IL×(ESR 1/(8 · Fs · Co))
3. Key Design Guide
| Module | Key points of design |
|---|---|
| PCB Layout | The bootstrap capacitor (VB-VS) is close to the pin, and the power path is short and wide |
| Thermal Management | QFN32 bottom heat dissipation pad connection 4-layer board inner copper foil |
| Short circuit protection | After the latch mechanism is triggered, the EN pin needs to be restarted to release the protection. |
| Soft Start | SS pin connected to 1μF capacitor to realize 5ms slow start (prevent current impact) |
Advantages of 4. compared to previous generation schemes
1. Integration degree improvement:Built-in power tube saves 2 external MOS,BOM cost is reduced by 15%
2. Wide pressure adaptability:Input voltage range 11-150V (previous generation CXSD62679 only supports 600V fixed topology)
3. Control flexibility"Added dead band adjustment (DT pin) and shutdown delay (EN pin) functions
4. Temperature performance:-45~125 ℃ industrial temperature wide, thermal resistance reduced by 40%(QFN32 vs SOP16)
Five. Component Parameters and Precautions in Application Design
1 Start-up process
CXSD62682 start mode, one of which is quickly started through the chip 1 pin VIN and provides power supply to VCC. Another by starting
The resistor charges the VCC external capacitor. When the VCC voltage is greater than VCC(on), the chip starts to work, outputs the PWM waveform, and the output voltage is established.
up, the output through the diode to the chip's VCC power supply.
2 Setting of switching frequency
Set the PWM switching frequency by connecting a resistor between the chip RI pin and GND. The specific frequency value can be determined by the following formula
FOSC (kHz) = 6150/RI (kΩ)
3 Setting of dead time
A resistor is connected between the DT pin and GND of the chip to set the dead time. The specific dead time value can be determined by the following formula
DT (NS) = 5 *rt (kΩ)
4 PCB layout
The capacitance between VCC and GND and the bootstrap capacitance between VB and VS are as close as possible to the chip pin; The large current path of the power tube is connected as wide and short as possible.
5 Output inductance
CXSD62682 work in continuous mode, the inductance can be selected according to the following formula
where Vin is the input voltage and Vout
Is the output voltage, Fs is the PWM operating frequency, Iripple is the peak-to-peak value of the current ripple in the inductor, and usually the Iripple is selected not to exceed the maximum output power.
30% of the flow.
6 Output capacitance
The output capacitor Co is used to filter the output voltage, so that the DC-DC voltage reducer outputs a relatively stable DC current to the load, and selects
When selecting a capacitor with low ESR as much as possible, the size of the selected capacitor value is mainly determined by the ripple requirement of the output voltage, which can be determined by the following formula:
where & Delta;Vo is output voltage ripple, & Delta;IL is inductor current ripple, Fs is PWM operating frequency, ESR
is the equivalent series resistance of the output capacitor.
7 Output voltage setting
The output voltage of the CXSD62682 is set by the two voltage dividing resistors on the FB pin, and the reference voltage of the internal error amplifier is 1.3V, as shown in the figure
8.5 shown in the figure, the output voltage Vout =(1 R1/R2)* 1.3V. If you need to set the output voltage to 14.3V, you can set R1 to 10K and R2 to 1K,
Output voltage Vout =(1 10/1)* 1.3V = 14.3V.
8 Turn off delay setting
The CXSD62682 shutdown delay is determined by the C8 R8 parameter value. The time constant is approximately t = 0.93 * C8 * R8. If you need to set a 14-second shutdown delay, C8 is 22uF and R8 is 680KΩ.
9 Peak current limit setting
CXSD62682 peak current limit The peak current Ipeak = 0.19V/RS1 is determined by the current limiting resistor R3 parameter.
The chip has been successfully applied to scenes such as electric motorcycle converter and 65W PD fast charging. Its 5 × 5mm QFN package (see section 9.1 size table for details) is compatible with automatic mounting. The complete design kit is available on the official website for reference design documents.
Technical Specification (Product PDF):Need detailed PDF specifications, please contact us, you can also get free samples and technical support!
Figure 6-1. Typical application of CXSD62682 VIN quick start power supply
Figure 6-2. Typical Application of CXSD62682 External Starting Resistor Feedback Power Supply
Figure 6-3. Typical Application of CXSD62682 Shutdown Delay
Figure 6-4. Typical application diagram of CXSD62682 fast charging scheme
Related Chip Selection GuideMore related products......
| Model | VCC starting voltage | VCC Shutdown Voltage | Input voltage range | Starting current | Switching frequency | Output voltage accuracy | Built-in power tube | Features | Encapsulation |
| CXDC65167 | 6.5V | 3.5V | 20-60V | Built-in Quick Start | 10-100K, peripheral can be set | 3% | There are | 48V battery-powered system step-down switching power supply chip | ESOP8 |
| CXAC85204 | 16V | 9V | 20-150V | 3uA | jitter frequency | 1.5% | There are | Non-isolated system constant voltage constant current output | SOP7 |
| CXAC85207 | 9.5V | 7.8V | 10-25V | 80uA | 0-300K, peripheral adjustable | 1.50% | None | programmable power chip | SOP16 |
| CXLB73135 | 9.5V | 7.8V | 10-25V | 80uA | 0-300K, peripheral adjustable | 1.50% | None | programmable power chip | SSOP24 |
| CXDC65168 | 6.5V | 3.5V | 10-600V | 200uA | 0-300K, peripheral can be set | 1.5% | None | Synchronous Rectification, HighEfficiencycan support the battery constant current constant voltage charging | SOP16 |
| CXSU63303 | - | - | 7-150V | External auxiliary power supply | 70K | 1.5% | None | The buck-boost control chip supports high-voltage and high-current protection solutions. | QFN32 |
| CXSU63304 | - | - | 13-90V | External auxiliary power supply | 100K | 1.5% | None | Buck-Boost Digital Power Chip Supporting PD3.0 Protocol | QFN64 |
| CXSU63305 | 3.65V | 3.6V | 4-600V | 50uA | 0-300K, peripheral can be set | 1.5% | None | Step-up synchronous rectification scheme to support high-voltage high-current scheme | SOP16 |
| CXSD62669 | 16V | 9V | 20-90V | 3uA | jitter frequency | 1.5% | There are | Non-isolated system constant voltage constant current output | SOP7 |
| CXSD62670 | 16V | 9V | 20-600V | 3uA | jitter frequency | 1.5% | There are | Non-isolated system constant voltage constant current output | SOP7 |
| CXSD62671 | - | - | 10-115V | Built-in Quick Start | 140KHz | 3% | None | Short circuit hiccup, flexible and adjustable output voltage | ESOP8 |
| CXSD62672 | - | - | 10-115V | Built-in Quick Start | 120KHz | 3% | None | Short circuit lock, flexible output voltage adjustable | ESOP8 |
| CXSD62673 | - | - | 10-100V | Built-in Quick Start | 120KHz | 3% | There are | Zero power consumption enable, flexible and adjustable output voltage | ESOP8 |
| CXSD62674 | - | - | 10-120V | Built-in Quick Start | 120KHz | 3% | There are | Zero power consumption enable, flexible and adjustable output voltage | ESOP8 |
| CXSD62675 | - | - | 10-120V | Built-in Quick Start | 120KHz | 3% | There are | Short circuit hiccup, flexible and adjustable output voltage | ESOP8 |
| CXSD62676 | - | - | 10-120V | Built-in Quick Start | 120KHz | 3% | None | Short circuit hiccup, flexible and adjustable output voltage | ESOP8 |
| CXSD62677 | - | - | 10-120V | Built-in Quick Start | 70KHz | 3% | None | Short circuit lock, flexible output voltage adjustable | ESOP8 |
| CXSD62678 | 4.6V | 3.8V | 4-600V | 50uA | 0-300K, peripheral can be set | 1.5% | None | Step-down synchronous rectification scheme to support high voltage and high current scheme | SOP16 |
| CXSD62679 | 16.5V | 8V | 10-600V | 200uA | 0-300K, peripheral can be set | 1.5% | None | Synchronous Rectification, HighEfficiencycan support the battery constant current constant voltage charging | SOP16 |
| CXSD62680 | 8.5V | 7.5V | 10-600V | 200uA | 0-300K, peripheral can be set | 1.5% | None | Synchronous Rectification, HighEfficiencycan support the battery constant current constant voltage charging | SOP16 |
| CXSD62681 | 9.5V | 7.8V | 11-250V | 200uA | 0-300K, peripheral can be set | 1.5% | None | Synchronous Rectification, HighEfficiency, short circuit lock, built-in temperature protection, etc. | SSOP16 |
| CXSD62682 | 9.5V | 7.8V | 11-100V | 200uA | 0-300K, peripheral can be set | 1.5% | There are | Synchronous Rectification, HighEfficiency, short circuit lock, built-in temperature protection, etc. | QFN32 |
| CXSD62683 | 9.5V | 7.8V | 11-30V | 200uA | 0-300K, peripheral can be set | 1.5% | There are | Synchronous Rectification, HighEfficiency, short circuit lock, built-in temperature protection, etc. | QFN32 |
| CXSD62684 | - | - | - | External auxiliary power supply | Maximum operating frequency 100KHz | - | None | Digital Algorithm Current Mode Synchronous Buck Control Chip | SSOP24 |
| CXSD62685 | 9.5V | 7.8V | 10-25V | 80uA | 0-300K, peripheral adjustable | 1.50% | None | Synchronous Rectifier Buck Power Supply Control Chip | SSOP16 |
