Datasheet LTC2950-1, LTC2950-2 (Linear Technology) - 6

LTC2950-1/LTC2950-2
pin FuncTions (TSOT-23/DFN) VIN (Pin 1/Pin 4):
Power Supply Input: 2.7V to 26.4V. turn-off) is detected. This pin can connect directly to a
PB (Pin 2/Pin 3):
Pushbutton Input. Connecting PB to DC/DC converter shutdown pin that provides an internal ground through a momentary switch provides on/off pull-up. Otherwise a pull-up resistor to an external supply control via the EN/EN pin. An internal 100k pull-up resis- is required. The operating range for this pin is 0V to 10V. tor connects to an internal 1.9V bias voltage. The rugged
EN (LTC2950-2, Pin 6/Pin 7):
Open Drain Enable Output. PB input can be pulled up to 26.4V externally without This pin is intended to enable system power. EN is asserted consuming extra current. low after a valid PB turn-on event. EN releases high if: a)
ONT (Pin 3/Pin 2):
Additional Adjustable Turn On Time KILL is not driven high (by µP) within 512ms of the initial Input. Placing an external capacitor to ground determines valid PB power turn-on event, b) KILL is driven low dur- the additional time (beyond the internal default 32ms) ing normal operation, c) a second valid PB event (power the PB pin must be held low before the enable output turn-off) is detected. This pin can connect directly to a is asserted. Floating this pin results in a default turn on DC/DC converter shutdown pin that provides an internal debounce time of 32ms. pull-up. Otherwise a pull-up resistor to an external supply is required. The operating range of this pin is 0V to 10V.
GND (Pin 4/Pin 1):
Device Ground.
OFFT (Pin 7/Pin 6):
Additional Adjustable Turn Off Time
INT (Pin 5/Pin 8):
Open Drain Interrupt Output. After a Input. A capacitor to ground determines the additional pushbutton turn-off event is detected, the LTC2950 inter- time (beyond the internal default 32ms) that the PB pin rupts the system (µP) by bringing the INT pin low. Once the must be held low before initiating a power down sequence system finishes its power down and housekeeping tasks, (INT falling). Floating this pin results in a default turn off it sets KILL low, which in turn releases the enable output. time of 32ms. If at the end of the power down timer (1024ms) KILL is still high, the enable output is released immediately. INT
KILL (Pin 8/Pin 5):
KILL Input. Forcing KILL low releases may optionally be tied to KILL to release the enable output the enable output. During system turn on, this pin is blanked immediately after the turn-off event has been detected by a 512ms internal timer to allow the system to pull KILL (INT = low). high. This pin has an accurate 0.6V threshold and can be used as a voltage monitor input. If unused, connect to a
EN (LTC2950-1, Pin 6/Pin 7):
Open Drain Enable Output. low voltage output supply (see Figure 6). This pin is intended to enable system power. EN is asserted high after a valid PB turn on event. EN is released low if: a)
Exposed Pad (Pin 9):
Exposed Pad may be left open or KILL is not driven high (by µP) within 512ms of the initial connected to device ground. valid PB power turn-on event, b) KILL is driven low dur- ing normal operation, c) a second valid PB event (power 295012fd 6 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Timing Diagrams Applications Information Typical Applications Package Description Revision History Typical Application Related Parts