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PWM Controller for Programmable Power Converter (USBPD)

RT7755xE

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The RT7755xE series operating with continuous conduction mode (CCM) is specifically designed to work with controllers, such as the RT7206, to provide a total solution for USB PD or a programmable power adapter. This RT7755xE not only provides a high power efficiency control scheme, but also gives a 50mW very low standby power control under 5V standby condition.

The RT7755xE is such a special design to achieve a wide-range of output voltage by utilizing several innovations, including (1) By using DMAG pin, the RT7755xE senses output voltage to adjust loop gain for system stability, to adjust output over-voltage protection threshold voltage to protect external devices, and to adjust current limit to meet Limited Power Source (LPS) safety requirements; (2) The RT7755xE is also equipped with comprehensive protection features, including bulk-capacitor brown-in/brown-out protection, VDD over-voltage protection (VDD OVP), output over-voltage/under-voltage protection (Output OVP/UVP), secondary rectifier short-circuit protection (SRSP), and external over-temperature protection (External OTP); (3) For constant output power regulation, a resistor connected to CS pin can be used to achieve accurate line compensation across the universal input voltage range; and (4) The RT7755xE also provides various features to protect against any failures occurring at the secondary-side component, such as the RT7206 or a shunt regulator.

In applications, it is suggested that the RT7755xE be used with a secondary controller RT7206 to realize a robust and safe design to prevent all potential fault conditions due to misconnection of various devices, cables, plugs and receptacles.

Applications

  • USB PD and Programmable Power Adapters
Key Spec.
RT7755AE RT7755LES
Status Active Active
Feedback Regulation Mode SSR SSR
Switching Frequency_Normal (kHz) 82.5 65
Switching Frequency_Peak (kHz) 82.5 65
Peak load Application No No
HV Start-up No No
CCM/Valley Multi-mode CCM/Valley Switching Multi-mode CCM/Valley Switching Multi-mode
Programmable Burst/Green-mode No No
Brown-in/out Yes (Buck cap.Side) Yes (Buck cap.Side)
OVP Adaptive OVP OVP
External OTP Yes Yes
UVLO ON (V) 17.5 17.5
UVLO OFF (V) 7 7
VDD OVP (V) 67 67
Features Current Mode Control;Cycle-by-Cycle Current Limit;OCP;OVP;PWM;SCP;UVP Current Mode Control;Cycle-by-Cycle Current Limit;OCP;OVP;PWM;SCP;UVP
Package Type SOT-26 SOT-26
Features
  • Optimized for Adaptive Output Power
    ► Wide VDD Range : 10V to 60V
    ► Adaptive Output Over-Voltage Protection
    ► Adaptive Over-Current Protection
    ► Adaptive Loop Gain Control for Loop Stability
  • High Efficiency
    ► Green Mode Operation at Light Load and No Load
  • Comprehensive Protection Features
    ► Bulk-Capacitor Brown-In and Brown-Out Protection
    ► VDD Over-Voltage Protection
    ► Output Over-Voltage and Under-Voltage Protection
    ► External Over-Temperature Protection
    ► Secondary Rectifier Short-Circuit Protection
    ► Programmable Line Compensation
  • Others
    ► < 50mW in 5V Standby Mode for Power Saving
    ► Driver Capability : 300mA/-300mA
    ► SmartJitterTM Technology
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