Ultra Low Power Synchronous Step-Down PFM DC/DC Converter for Low Output Voltage
XC9272 series are Ultra Low Power synchronous-rectification type PFM step down DC/DC converters with a built-in 0.4Ω (TYP.) Pch driver and 0.4Ω (TYP.) Nch synchronous switching transistor, designed to allow the use of ceramic capacitor.
PFM control enables a low quiescent current, making these products ideal for battery operated devices that require high efficiency and long battery life.
Only inductor, CIN and CL capacitors are needed as external parts to make a step down DC/DC circuit.
Operation voltage range is from 2.0V to 6.0V. This product has fixed output voltage from 0.6V to 0.95V(accuracy: ±20mV) in increments of 0.05V.
During stand-by, all circuits are shutdown to reduce consumption to as low as 0.1μA(TYP.) or less.
With the built-in UVLO (Under Voltage Lock Out) function, the internal P-channel MOS driver transistor is forced OFF when input voltage gets lower than UVLO detection voltage. Besides, XC9272 series has UVLO release voltage of 1.8V (TYP.).
The product with CL discharge function, XC9272B type, can discharge CL capacitor during stand-by mode due to the internal resistance by turning on the internal switch between VOUT -GND. This enables output voltage restored to GND level fast.
Typical Application Circuit
|Input Voltage Range||2.0V～6.0V|
|Output Voltage Range||0.6V～0.95V(±20mV,0.05V increments)|
|Driver Transistor||0.4Ω (Pch Driver Tr)
0.4Ω (Nch Synchronous rectifier Switch Tr)
|High Speed Transient||50mV(VIN=3.6V,VOUT=0.7V,IOUT=10μA→50mA)|
|PFM Switching Current||180mA|
|Functions||Short Circuit Protection
Low ESR Ceramic
|Operating Ambient Temperature||-40～+85℃|
|Environmentally Friendly||EU RoHS compliant, Pb free|
|Package||SOT-25||Number of Pins||5|
|Pcs/Reel||3,000||Package Size(mm)||2.8 x 2.9 x 1.3|
|Package||USP-6EL||Number of Pins||6|
|Pcs/Reel||3,000||Package Size(mm)||1.8 x 2.0 x 0.4|
How does the CL discharge function work?
The function rapidly releases the charge remained in the CL capacitor to make the VOUT pin voltage zero. The VOUT pin voltage does not reach zero immediately after being turned off by the CE function due to the charge remained in the connected CL capacitor. While the charge in the CL capacitor is gradually reaching zero, the LSI continues operating and does not work with the CE pin signal, which may cause a malfunction. This is why the discharge is required when turning off the CE pin. A larger capacitance of the capacitor needs longer time to be discharged.
What does CL mean?
Load capacitor. Other companies often refer to it as COUT.
What is the standby current?
The current that flows through the IC in the standby mode. The standby mode means the state where the IC has been turned off by the CE function.
What does the FB product mean?
An IC for which any output voltage can be set by the reference voltage of the FB pins and the external dividing resistor. The output voltage is determined by the RFB1 and RFB2 values, using the following formula: VOUT = Vref × (RFB1 + RFB2)/RFB2
How does UVLO (under voltage lockout) work?
This circuit forcibly turns off the driver transistor when VIN drops below the UVLO voltage. If the input voltage recovers to the value which is equal to the specified value or more, UVLO will be released to resume the switching operation. It is resumed by the soft-start function. The paused state by UVLO is not the shutdown. The pulse output is stopped, but the internal circuit is operating.