The JTMA8819 JTMA8820 JTMA8821 integrates a synchronous buck

　　一,产品概述(General Description)
The JTMA8819 JTMA8820 JTMA8821 integrates a synchronous buck PWM con-troller
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 JTMA8819 provides excellent transient response and accurate DC voltage output in PFM Mode. In Pulse Fre-quency Mode (PFM), the JTMA8819 provides very high efficiency over light to heavy loads with loading-modulated
switching frequencies.
The JTMA8819 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.
An internal resistor divider is used to provide a half voltage of VDDQSNS 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 JTMA8819 is available in 3mmx3mm 20-pin QFN and 3mmx3mm 16-pin TQFN packages.

二.产品特点(Features)
High Input Voltages Range from 3V to 28V Input Power
Provide 1.8V (DDR2), 1.5V (DDR3) or Adjustable
Output Voltage from 0.5V to 2V
- ±1% Accuracy Over-Temperature
Build in VREF Voltage 1.8V ±1% Accuracy over Temperature
Integrated MOSFET Drivers
Integrated Bootstrap Forward P-CH MOSFET
Excellent Line and Load Transient Responses
PFM Mode for Increased Light Load Efficiency
Selectable 300kHz/400kHz/500kHz Switching Frequebcies
Integrated MOSFET Drivers and Bootstrap Diode
S3 and S5 Pins Control The Device in S0, S3, or S4/S5 State
Power Good Monitoring
50% Under-Voltage Protection (UVP)
125% Over-Voltage Protection (OVP)
Adjustable Current-Limit Protection
- Using Sense Low-Side MOSFET RDS(ON)
QFN-20 3mmx3mm Package (QFN-20) and
QFN-16 3mmx3mm Thin Package (TQFN-16)
Lead Free Available (RoHS Compliant)
+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)
Thermal Shutdown Protection

三,应用范围 (Applications)
DDR2, and DDR3 Memory Power Supplies
SSTL-2 SSTL-18 and HSTL Termination

四.下载产品资料PDF文档

JTMA8819

JTMT8820

JTMT8821