ADP1046:隔離DC-DC副邊應(yīng)用控制器應(yīng)用詳解

ADP1046是一款靈活的數(shù)字副邊控制器，設(shè)計(jì)用于AC-DC和隔離DC-DC副邊應(yīng)用。ADP1046與ADP1043A引腳兼容，具有一些性能改進(jìn)和新特性，包括電壓前饋、改進(jìn)環(huán)路響應(yīng)，以及可編程死區(qū)控制，以實(shí)現(xiàn)最高效率。
　　ADP1046還為實(shí)現(xiàn)最低元件數(shù)量、最大靈活性和最少設(shè)計(jì)時間進(jìn)行了優(yōu)化。具體特性包括本地和遠(yuǎn)程電壓檢測、原邊和副邊電流檢測、數(shù)字脈寬調(diào)制（PWM）產(chǎn)生、均流和冗余OrFET控制。控制環(huán)路數(shù)字濾波器和補(bǔ)償功能已集成至該器件，可通過I2C 接口編程?？删幊瘫Ｗo(hù)功能包括過流保護(hù)（OCP）、過壓保護(hù)（OVP）、欠壓閉鎖（UVLO）和過溫保護(hù)（OTP）。
　　內(nèi)置的EEPROM允許對集成的環(huán)路濾波器、PWM信號時序、浪涌電流和軟啟動時序進(jìn)行廣泛的編程。通過內(nèi)置校驗(yàn)和及可編程保護(hù)電路，可靠性得以提高。
　　全面的GUI簡化了環(huán)路濾波器特性的設(shè)計(jì)和安全特性的編程。工業(yè)標(biāo)準(zhǔn)I2C總線可用于訪問許多監(jiān)控和系統(tǒng)測試功能。
　　ADP1046提供32引腳LFCSP封裝，采用3.3 V單電源供電。
　　控制理論
　　電流檢測
　　The ADP1046 has two current sense inputs： CS1 and CS2±。 These inputs sense， protect， and control the primary input current， secondary output current， and the share bus information. They can be calibrated to reduce errors due to external components.
　　CS1操作（CS1）
　　CS1 is typically used for the monitoring and protection of the primary side current， which is commonly sensed using a current transformer （CT）。 The input signal at the CS1 pin is fed into an ADC for current monitoring. The range of the ADC is 0 V to 1.4 V. The input signal is also fed into a comparator for pulse-by-pulse OCP protection. The typical configuration for the CS1 current sense is shown in Figure 1.
　　
　　Figure 1
　　The CS1 ADC is used to measure the average value of the primary current; the reading is averaged every 2.62 ms in an asynchronous fashion to make fault decisions. The ADP1046 also writes the 12-bit CS1 reading every 10 ms to Register 0x13.
　　The fast OCP comparator is used to limit the instantaneous primary current within each switching cycle and has a nominal threshold of 1.2 V.Various thresholds and limits can be set for CS1， as described in the Current Sense and Current Limit Registers section.
　　CS2 操作（CS2+， CS2?）
　　CS2+ and CS2? are differential inputs used for the monitoring and protection of the secondary side current. The full-scale range of the CS2 ADC is programmable to 60 mV or 120 mV. The differential inputs are fed into an ADC through a pair of external resistors that provide the necessary level shifting. The device pins， CS2+ and CS2?， are internally regulated to approxi-mately 1 V by internal current sources.
　　When using low-side current sensing， the current sources are 200 μA; therefore， the required resistor value is 1 V/200 μA = 5 kΩ。 When using high-side current sensing， the current sources are 2 mA; therefore， the resistor value required is （VOUT ? 1 V）/2 mA. In the case of VOUT = 12 V， the required resistor value is 5.5 kΩ。