Datasheet LTC3108-1 (Analog Devices) - 7

LTC3108-1
pin FuncTions (DFN/SSOP) VAUX (Pin 1/Pin 2):
Output of the Internal Rectifier Cir-
VS1 (Pin 8/Pin 11):
VOUT Select Pin 1. Connect this pin cuit and VCC for the IC. Bypass VAUX with at least 1µF of to ground or VAUX to program the output voltage (see capacitance. An active shunt regulator clamps VAUX to Table 1). 5.25V (typical).
VOUT2_EN (Pin 9/Pin 12):
Enable Input for VOUT2. VOUT2
VSTORE (Pin 2/Pin 3):
Output for the Storage Capacitor will be enabled when this pin is driven high. There is an or Battery. A large capacitor may be connected from this internal 5M pull-down resistor on this pin. If not used, pin to GND for powering the system in the event the input this pin can be left open or grounded. voltage is lost. It will be charged up to the maximum VAUX
C1 (Pin 10/Pin 13):
Input to the Charge Pump and Rectifier clamp voltage. If not used, this pin should be left open Circuit. Connect a capacitor from this pin to the secondary or tied to VAUX. winding of the step-up transformer.
VOUT (Pin 3/Pin 4):
Main Output of the Converter. The
C2 (Pin 11/Pin 14):
Input to the N-Channel Gate Drive voltage at this pin is regulated to the voltage selected by Circuit. Connect a capacitor from this pin to the secondary VS1 and VS2 (see Table 1). Connect this pin to an energy winding of the step-up transformer. storage capacitor or to a rechargeable battery.
SW (Pin 12/Pin 15):
Drain of the Internal N-Channel
VOUT2 (Pin 4/Pin 5):
Switched Output of the Converter. Switch. Connect this pin to the primary winding of the Connect this pin to a switched load. This output is open transformer. until VOUT2_EN is driven high, then it is connected to VOUT through a 1.3Ω P-channel switch. If not used, this
GND (Pins 1, 8, 9, 16) SSOP Only:
Ground pin should be left open or tied to VOUT. The peak current
GND (Exposed Pad Pin 13) DFN Only:
Ground. The DFN in this output is limited to 0.3A typical. exposed pad must be soldered to the PCB ground plane.
VLDO (Pin 5/Pin 6):
Output of the 2.2V LDO. Connect a It serves as the ground connection, and as a means of 2.2µF or larger ceramic capacitor from this pin to GND. conducting heat away from the die. If not used, this pin should be tied to VAUX.
Table 1. Regulated Voltage Using Pins VS1 and VS2 PGD (Pin 6/Pin 7):
Power Good Output. When V
VS2 VS1 V
OUT is
OUT
within 7.5% of its programmed value, PGD will be pulled GND GND 2.5V up to VLDO through a 1MΩ resistor. If VOUT drops 9% GND VAUX 3V below its programmed value PGD will go low. This pin VAUX GND 3.7V can sink up to 100µA. VAUX VAUX 4.5V
VS2 (Pin 7/Pin 10):
VOUT Select Pin 2. Connect this pin to ground or VAUX to program the output voltage (see Table 1). 31081fb For more information www.linear.com/LTC3108-1 7 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration order information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Typical Application Related Parts