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目录
一,产品概述(General Description) The JTMA8813/A integrates a synchronous buck PWM controller to generate VDDQ, a sourcing and sinking LDO linear regulator to generate VTT. It provides a complete power supply for DDR2 and DDR3 memory system. It offers the lowest total solution cost in system where space is at a premium. The JTMA8813/A provides excellent transient response and accurate DC voltage output in either PFM or PWM Mode. In Pulse Frequency Mode (PFM), the JTMA8813/A provides very high efficiency over light to heavy loads with loading-modulated switching frequencies. On TQFN4x4- 24A package, the Forced PWM Mode works nearly at con- stant frequency for low-noise requirements. The JTMA8813/A is equipped with accurate current-limit,output under-voltage, and output over-voltage protections.A Power-On-Reset function monitors the voltage on VCC prevents wrong operation during power on.The LDO is designed to provide a regulated voltage with bi-directional output current for DDR-SDRAM termination.The device integrates two power transistors to source or sink current up to 1.5A. It also incorporates current-limit and thermal shutdown protection.The output voltage of LDO tracks the voltage at VTTREF pin. An internal resistor divider is used to provide a half voltage of VDDQ for VTTREF and VTT Voltage. The VTT output voltage is only requiring 20µF of ceramic output capacitance for stability and fast transient response. The S3 and S5 pins provide the sleep state for VTT (S3 state)and suspend state (S4/S5 state) for device, when S5 and S3 are both pulled low the device provides the soft-off for VTT and VTTREF. The JTMA8813/A is available in 4mmx4mm 24-pin TQFN package, and the JTMA8813A is available in 3mmx3mm 20-pin TQFN package. 二.产品特点(Features) Buck Controller (VDDQ) · High Input Voltages Range from 3V to 28V Input Power Provide 1.8V (DDR2), 1.5V (DDR3) or Adjustable Output Voltage from 0.75V to 5.5V - ±1% Accuracy Over-Temperature Integrated MOSFET Drivers and Bootstrap Diode Excellent Line and Load Transient Responses PFM Mode for Increased Light Load Efficiency Constant-On-Time Controller Scheme - Switching Frequency Compensation for PWMMode - Adjustable Switching Frequency from 100kHz to 550kHz in PWM Mode with DC Output Current Integrated MOSFET Drivers and Bootstrap Diode S3 and S5 Pins Control The Device in S0, S3, or S4/S5 State Power Good Monitoring 70% Under-Voltage Protection (UVP) 125% Over-Voltage Protection (OVP) Adjustable Current-Limit Protection Using Sense Low-Side MOSFET RDS(ON) ±1.5A LDO Section (VTT) Souring or Sinking Current up to 1.5A Fast Transient Response for Output Voltage Output Ceramic Capacitors Support at Least 10µF MLCC VTT and VTTREF Track at Half the VDDQSNS by Internal Divider ±20mV Accuracy for VTT and VTTREF Independent Over-Current-Limit (OCL) (责任编辑：oumao18) |
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