LT1312 Linear Technology, LT1312 Datasheet
LT1312
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LT1312 Summary of contents
Page 1
... LT1312 provides 0V, 3.3V, 5V, 12V and Hi-Z regulated power to the VPP pin of a PCMCIA card slot from a single unregulated 13V to 20V supply. When used in conjunction with a PC card interface controller, the LT1312 forms a complete minimum component-count interface for palm- top, pen-based and notebook computers. The VPP output ...
Page 2
... Program to 12V 0.4V VALID Program to 0V 12V VALID Note 1: For junction temperatures greater than 110 C, a minimum load of 1mA is recommended INFORMATION ORDER PART TOP VIEW NUMBER 8 VPP OUT 7 N.C. LT1312CS8 SENSE 5 S8 PART MARKING S8 PACKAGE 1312 = 125 C, = 150 MIN TYP MAX 11.52 12.00 12.48 4.75 5 ...
Page 3
... Quiescent Current (3.3V/5V Mode) 250 T = 25°C J EN0 = 0V EN1 = 5V 200 150 100 SENSE 3.3V SENSE SUPPLY VOLTAGE (V) LT1312 G3 Ground Pin Current (3.3V Mode) 2 25°C J EN0 = 0V EN1 = 5V 2 3.3V SENSE 1 110 30mA 330 10mA* L 0.5 *FOR VPP = 3 ...
Page 4
... VALID OUTPUT CURRENT (mA) LT1312 G14 Line Transient Response (12V 1µF OUT 10µF OUT –20 – –0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 TIME (ms) LT1312 G17 V Sense Threshold Voltage CC 5 25° 15V S 5.0 4.5 SWITCH TO 5V 4.0 SWITCH TO 3.3V 3.5 3.0 2 100 125 JUNCTION TEMPERATURE (°C) LT1312 G12 ...
Page 5
... The supply pin should be bypassed to ground if the device is more than 6 inches away from the main supply capacitor. A bypass capacitor in the range of 0 sufficient. The supply voltage to the LT1312 can be loosely regulated between 13V and 20V. See Applica- tions Information section for more detail. ...
Page 6
... LT1312 falls between 13V and 20V under all load conditions. The 9V output from this additional winding is rectified by diode D2, added to the main 5V output and applied to the input of the LT1312. (Note that the auxiliary winding must be phased properly as shown in Figure 1.) The auxiliary winding is referenced to the 5V output which provides DC current feedback from the auxiliary supply to the main 5V section ...
Page 7
... LTC1142HV. Continuous mode operation is only invoked when the LT1312 is programmed to 12V. If the LT1312 is pro- grammed to 0V, 3.3V or 5V, power is obtained directly from the main power source (battery pack) through diode D1. Again, the LT1312 output can be loaded without regard to the loading of the main 5V output ...
Page 8
... VPP pin requires 3.3V or 5V. For these lower input voltages this technique is no longer valid as the input will fall below the LT1312 regulator’s dropout voltage. To correct for this situation, the additional switch Q4 forces the switching regulator into continuous mode operation whenever 3 ...
Page 9
... PC card, or the switching power supply in the event of an accidental short circuit. Output Capacitance The LT1312 is designed to be stable with a wide range of output capacitors. The minimum recommended value with an ESR less. The capacitor is connected directly between the output pin and ground as shown in Figure 6 ...
Page 10
... Heat sinking, for surface mounted devices, is accom- plished by using the heat spreading capabilities of the PC board and its copper traces. The junction temperature of the LT1312 must be limited to 125 C to ensure proper operation. Use Table 1 in conjunc- tion with the typical performance graphs, to calculate the ...
Page 11
... V S EN0 VPP OUT EN1 LT1312 VALID SENSE + GND Si9410DY OR IN1 G1 MMSF5N02HD LTC1157CS8 IN2 G2 Si9956DY OR GND MMDF3N02HD 3.3V LT1312 VPP1 + VPP2 1 F PCMCIA CARD SLOT LT1312 TA2 VPP1 VPP2 PCMCIA CARD SLOT 3. LT1312 TA3 11 ...
Page 12
... LT1312 PACKAGE DESCRIPTION 0.010 – 0.020 45 (0.254 – 0.508) 0.008 – 0.010 (0.203 – 0.254) 0.016 – 0.050 0.406 – 1.270 *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 INCH (0.15mm). RELATED PARTS See PCMCIA Product Family table on the first page of this data sheet. ...