High Efficiency Boost Converter
General Description
The RT4812 allows systems to take advantage of new battery chemistries that can supply significant energy when the battery voltage is lower than the required voltage for system power ICs. By combining built-in power transistors, synchronous rectification, and low supply current; this IC provides a compact solution for systems using advanced Li-Ion battery chemistries. The RT4812 is a boost regulator designed to provide a minimum output voltage from a single-cell Li-Ion battery, even when the battery voltage is below system minimum. In boost mode, output voltage regulation is guaranteed to a maximum load current of 2.1A. Quiescent current in Shutdown Mode is less than 1?A, which maximizes battery life.
Features
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CMCOT Topology and Small Output Ripplewhen VIN close VOUT Voltage
Operates from a Single Li-ion Cell : 1.8V to 5.5VAdjustable Output Voltage : 1.8V to 5.5VPSM Operation
Up to 96% EfficiencyBoost Current Limit
Output Over Voltage Protection
Pin Adjustable Average Output Current LimitThreshold (2 levels)Internal CompensationOutput Discharge
Output Short ProtectionTrue Load Disconnect
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Ordering Information
RT4812Package TypeJ8F : TSOT-23-8 (FC)Lead Plating SystemG : Green (Halogen Free and Pb Free)Note :
Richtek products are :
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Applications
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Single-Cell Li-Ion, LiFePO4 Smart-PhonesPortable Equipment
Marking Information
0L=DNN0L= : Product CodeDNN : Date CodeRoHS compliant and compatible with the currentrequirements of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
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Simplified Application Circuit
L1VINC1VINC2ENR3H/LILIMGNDFBR2RT4812SWVOUTR1C3VOUTDS4812-02 October 2015
RT4812
Operation
RT4812
combined
built-in
power
transistors,
Startup and Shutdown State
When VIN is rising and through the LIN state, it will enter the Startup state. If EN is pulled low, any function is turned-off in shutdown mode. Soft-Start State
It starts to switch in Soft-start state. After the LIN state, output voltage is rising with the internal reference voltage. Fault State
As the Figure 1 shown, it will enter to the Fault state as below,
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synchronous rectification, and low supply current, it provides a compact solution for system using advanced Li-Ion battery chemistries.
In boost mode, output voltage regulation is guaranteed to a maximum load current of 2.1A. Quiescent current in Shutdown mode is less than 1?A, which maximizes battery life. Mode LIN LIN 1 LIN 2 Depiction Linear startup 1 Linear startup 2 Boost soft-start Boost mode Condition VIN > VOUT VIN > VOUT VOUT < VOUT(MIN) VOUT = VOUT(MIN) Soft-Start Boost LIN State
The timeout of LIN2 is over the 1024?s.
It will be the high impedance between the input and output when the fault is triggered. A restart will be start after 20ms. OCP
The converter senses the current signal when the high-side P-MOSFET turns on. As a result, the OCP is cycle by-cycle current limitation. If the OCP occurs, the converter holds off the next on pulse until inductor current drops below the OCP limit. OTP
The converter has an over-temperature protection. When the junction temperature is higher than the thermal shutdown rising threshold, the system will be latched and the output voltage will no longer be regulated until the junction temperature drops under the falling threshold.
When VIN is rising, it enters the LIN State. There are two parts for the LIN state. It provides maximum current for 1A to charge the COUT in LIN1, and the other one is for 3A in LIN2. By the way, the EN is pulled high and VIN > UVLO.
As the figure shown, if the timeout is over the specification, it will enter the Fault mode.
EN = 1, Vin > UVLOLIN 1Timeout < 512μsTimeout > 512μsSoft-StartTimeout < 1024μsBoost modeLIN 2Timeout > 1024μsFault StateFigure 1. RT4812 State Chart
DS4812-02 October 2015
RT4812
Absolute Maximum Ratings (Note 1)
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VIN, VINA to GND -------------------------------------------------------------------------------------------------- ?0.2V to 6VVOUT to GND -------------------------------------------------------------------------------------------------------- 6.2VPower Dissipation, PD @ TA = 25?C
TSOT-23-8 (FC) ----------------------------------------------------------------------------------------------------- 1.78WPackage Thermal Resistance (Note 2)
TSOT-23-8 (FC), ?JA ----------------------------------------------------------------------------------------------- 56?C/WTSOT-23-8 (FC), ?JC ----------------------------------------------------------------------------------------------- 28?C/WLead Temperature (Soldering, 10sec.) ------------------------------------------------------------------------- 260?C
Junction Temperature -------------------------------------------------------------------------------------------- ?65?C to 150?CStorage Temperature Range ------------------------------------------------------------------------------------- ?65?C to 150?CESD Susceptibility (Note 3)
HBM (Human Body Model) -------------------------------------------------------------------------------------- 2kVMM (Machine Model) ---------------------------------------------------------------------------------------------- 200V
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Recommended Operating Conditions (Note 4)
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Input Voltage Range ---------------------------------------------------------------------------------------------- 1.8V to 5.5VOutput Voltage Range --------------------------------------------------------------------------------------------- 1.8V to 5.5VJunction Temperature (TJ) Range------------------------------------------------------------------------------- ?40?C to 125?CAmbient Temperature (TA) Range ------------------------------------------------------------------------------ ?40?C to 85?C
Electrical Characteristics
(VIN = 3.6V, TA = 25?C, unless otherwise specified) Parameter Supply Voltage Output Voltage Under Voltage Lockout Rising Threshold Under Voltage Lockout Falling Threshold FB Voltage Regulated DC VOUT Voltage Shutdown Current Quiescent Current Pre-charge Current Switching Frequency Symbol VIN VOUT UVLO_RISEUVLO_FallingVFB VOUT ISHDN Test Conditions VIN ? VOUT ??0.2V VIN ? VOUT ??0.2V Min 1.8 1.8 1.5 1.3 Typ -- -- 1.65 1.55 0.5 -- 0.1 90 1 0.5 -- -- 45 Max 5.5 5.5 1.8 1.7 0.505 4 2 -- -- -- -- -- -- Unit V V V V V % ?A?AA MHz A m? Force PWM 1.8 ? VIN ? VOUT ? 0.2V IOUT = 0mA (PSM) EN = 0V Close loop, no load FB = 3V, non-switching current 0.495 ?2-- -- -- Ipre fSW VOUT ? VIN > 1V ILIM = L ILIM = H VIN = 5V -- 1 2.1 -- Average Output Current Limit ILIMHigh Side Switch Ron DS4812-02 October 2015
RT4812
Parameter Low Side Switch Ron FB Pin Input Leakage Leakage of SW Line Regulation Load Regulation Output Over Voltage Protection EN Input Low Voltage EN Input High Voltage EN Sink Current Thermal Shutdown Thermal Shutdown Hysteresis TSD ?TSDIFB ISW?VOUT, LINE?VOUT, LOADVOVPVIL VIH All switch off VIN = 2.7V to 4.5V, VOUT = 5V, IOUT = 1500mA CCM, IOUT ? 2A, VIN = 3.6V, VOUT = 5V Symbol Test Conditions VIN = 5V Min -- ?1-- ?2?1.55.8 -- 1.2 -- -- -- Typ 30 -- -- -- -- 6 -- -- 0.1 160 30 Max -- 1 5 2 1.5 6.2 0.4 -- 1 Unit m? ?A?A% % V V V ?A?C?CDS4812-02 October 2015
RT4812
Typical Operating Characteristics
Efficiency vs. Output Current1009080VIN = 4.2VVIN = 2.5VVIN = 1.8VVIN = 3.6V1009080VIN = 2.5VVIN = 1.8VEfficiency vs. Output CurrentEfficiency (%)Efficiency (%)7060504030201000706050403020VOUT = 5V, L = 1.5μH (TDK SPM6530)COUT = 22μF x 24008001200160020001000400VOUT = 3.6V, L = 1.5μH (TDK SPM6530)COUT = 22μF x 2800120016002000Output Current (mA)Output Current (mA)Efficiency vs. Outout Current1009080VIN = 4.2VVIN = 3.3VVIN = 2.5VVIN = 1.8VVIN = 3.7V1009080Efficiency vs. Output CurrentVIN = 2.5VVIN = 1.8VEfficiency (%)Efficiency (%)70605040302010007060504030201000VOUT = 5V, L = 1.5μH (TDK SPM6530), R1 = 909k,R2 = 100k, COUT = 22μF x 24008001200160020002400VOUT = 3.6V, L = 1.5μH (TDK SPM6530), R1 = 909k,R2 = 100k, COUT = 22μF x 24008001200160020002400Outout Current (mA)Output Current (mA)Load Current vs. Output Voltage2.5ILIM = HOutput Voltage RippleLX(2V/Div)2.0Load Current (A)1.51.0ILIM = L0.5VOUT_ac(50mV/Div)VBAT= 2.5V, VOUT= 5V, IOUT= 0mAL = 1.5?H, COUT= 22?F x 20.044.24.44.64.85Output Voltage (V)Time (10?s/Div)DS4812-02 October 2015
MEMORY存储芯片RT4812GJ8F中文规格书 - 图文
