Datasheet LTC3541-1 (Analog Devices) - 9

LTC3541-1
BLOCK DIAGRAM
2.2µH IOUT(BUCK) = 500mA VIN(MIN) LVOUT + 1.4V 10µF 10 V SW IN 10µF 1 500mA BUCK VIN SW 22pF REF BUCKFB FB 3 GND PGND LVIN 6 VLDO/LINEAR REG VIN LVIN REF REF ENBUCK + LVOUT(MAX) < VIN – 1.4V 2 IOUT = 300mA (VLDO REG) ENVLDO CONTROL IOUT = 30mA (LINEAR REG) 9 LFB LOGIC – MODE LVOUT CNTRL 5 8 GND 2.2µF LFB 4 GND PGND 7 11 35411 F01
Figure 1. LTC3541-1 Functional Block Diagram OPERATION
The LTC3541-1 contains a high efficiency synchronous into consideration when using the buck regulator to pro- buck converter, a very low dropout regulator (VLDO) and vide the power for both the VLDO and for external loads. a linear regulator. It can be used to provide up to two With the ENBUCK pin driven to a logic low and ENVLDO output voltages from a single input voltage making the driven to a logic high, the LTC3541-1 enables the linear LTC3541-1 ideal for applications with limited board space. regulator, providing a low noise regulated output voltage The combination and configuration of these major blocks at the LV within the LTC3541-1 is determined by way of the control OUT pin while drawing minimal quiescent current from the V pins ENBUCK and ENVLDO as defined in Table 1. IN input pin. This feature allows output voltage LVOUT to be brought into regulation without the presence With the ENBUCK pin driven to a logic high and ENVLDO of the LVIN voltage. driven to a logic low, the LTC3541-1 enables the buck With the ENBUCK and ENVLDO pins both driven to a converter to efficiently reduce the voltage provided at logic high, the LTC3541-1 enables the high efficiency the VIN input pin to an output voltage which is set by an buck converter and VLDO regulator, providing dual output external feedback resistor network. The buck regulator operation from a single input voltage. When configured in can be configured for Pulse-Skip or Burst Mode opera- this manner, the LTC3541-1’s auto start-up sequencing tion by driving the MODE pin to a logic high or logic low feature will bring the VLDO/linear regulator output into respectively. The buck regulator is capable of providing a regulation in a controlled manner prior to enabling the maximum output current of 500mA, which must be taken 35411fb For more information www.linear.com/LTC3541-1 9 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Revision History Related Parts