600mA Synchronous Step-Down DC/DC Converter + Dual LDO Regulator
The XCM520 series is a multi chip module which comprises of a 600mA driver transistor built-in synchronous step down DC/DC converter and a dual CMOS LDO regulator. The device is housed in small USP-12B01 package which is ideally suited for space conscious applications.
The XCM520 can replace this dual DC/DC to eliminate one inductor and reduce output noise.
The DC/DC converter with a built-in 0.42ΩP-channel MOS and a 0.52ΩN-channel MOS provides a high efficiency, stable power supply up to 600mA to using only a coil and two ceramic capacitors connected externally.
The highly accurate, low noise, dual CMOS LDO regulator includes a reference voltage source, error amplifiers, driver transistors, current limiters and phase compensation circuits internally. The series is also fully compatible with low ESR ceramic capacitors.
This high level of output stability is maintained even during frequent load fluctuations, due to the excellent transient response performance and high PSRR achieved across a broad range of frequencies. The EN function allows the output of each regulator to be turned off independently, resulting in greatly reduced power consumption.
Typical Application Circuit
|DC/DC Converter Block|
|P-channel MOS Built-in||0.42Ω|
|N-channel MOS Built-in||0.52Ω|
|Input Voltage Range||2.7V～6.0V|
|Protection Circuits||Current Limiter Circuit Built-In,(Constant Current & Latching)|
|Control||Fixed PWM, Auto PWM/PFM|
|Dual LDO Regulator Block|
|MaximumOutput Current||150mA(300mA limitTYP.)|
|Operating Voltage Range||1.5V～6.0V|
|Output Voltage Range||1.8(VOUT1),1.2V(VOUT2)|
|Low Quiescent Current||25μA(TYP.)|
|Stand-by Current||Lsee than 0.1μA(TYP.)|
|High Ripple Rejection:||70dB@1kHz|
|Noise||Low Output Noise|
|Operating Ambient Temperature||-40℃～+85℃|
|Low ESR Capacitor||Low ESR Ceramic|
|Package||USP-12B01||Number of Pins||12|
|Pcs/Reel||3,000||Package Size(mm)||2.3 x 2.8 x 0.6|
What does the standby mode mean in the case of the multi channel IC?
It means the state where the entire IC has been turned off. For Torex products, it means that the pin voltages of EN1 and EN2 are both 0V.
How does the GO function of DC/DC converters work? Does it work just like a regulator?
Torex regard the PWM/PFM automatic switch control function as Green Operation (GO) in the case of DC/DC. The GO function is defined as the switching operation between the PFM mode for a small output current and the PWM mode for a large output current. The PFM control method controls the output current by increasing and decreasing the fall time according to the output current while keeping a pulse width. The PWM control method controls the output current by adjusting the pulse width of the rise time, which keeps the rise/fall time interval constant and increases the efficiency at a heavy load. By switching between the PFM control for a small output current and the PWM control for a large output current, the quiescent current can be controlled for both of heavy and light loads.
What is the soft-start function?
The function to soften the rise to prevent the inrush current.
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.