Features

0V, VCC, 12V or Hi-Z digital selection

120mA output current capacity

Internal current limit and heat shutdown

[

123]从3.3V自动切换至5V

从未经调节的13V至20V电源供电

逻辑兼容标准PCMCIA控制器

1μF输出电容器

[ 123] 30 μA static current in Hi-Z or 0V mode

VPP valid status feedback signal

No VPP overrun

8-needle SO packaging

Application

Note computer

Palm computer

Stroke computer

Handheld terminal

Barcode reader

Flash memory programming

explains

lt #174; 1312 is a PCMCIA driver/regulator family of a member company of linear technology. This LT1312 provides 0V, 3.3V, 5V, 12V, and Hi-Z adjustment 13V to 20V power supply from a single PCMCIA card slot to VPP pin. When using it, the LT1312 uses the PC card interface controller to form a complete minimum component counter for the palm computer, pen -type computer and laptop. The VPP output voltage is selected by two logical compatible digital inputs directly and the industrial standard PC card interface interface controller. Automatic 3.3V to 5V switches are provided and automatically adjusted the adjustable VPP output by selecting VPP u003d VCC mode by selecting VPP u003d VCC mode to match the VCC. In the following circumstances, the effective output of the opening of the circuit collector VPP is driven by the low VPP adjustment to 12 volts. LT1312 provides 8 stitches so packing

Absolutely maximum rated value

Power voltage 22 volt

Digital input voltage 7V to Input voltage 7V to (GND – 0.3V)

effective output voltage 15V to (GND – 0.3V)

The short -circuit duration of the output is uncertain

The operating temperature 0 ° C 0 ° C To 70 ° C

Kid temperature 0 ° C to 125 ° C

Storage temperature range -65 ° C to 150 ° C

Lead temperature (welding, 10 seconds) 300 degrees Celsius

Electric characteristics vs u003d 13V to 20V, TA u003d 25 ° C,Unless otherwise indicated.

indicates the standard temperature range suitable for the entire operation.

Note 1: For the knot temperature above 110 ° C, the minimum load is recommended to be 1MA.

Typical performance features

pin function

Essence Power insertion should be bypassing. If the distance between the device and the main pipeline exceeds 6 inches, a capacitor is provided. The bypass container within 0.1 μF is enough to 1 μF. The power supply voltage of the LT1312 CAN is loosened between 13V and 20V. For details, see the application information section. VPOUT pin: This adjustment output is the PCMCIA card VPP pin that is usually connected together at the bayonet. The VPOUT output current is limited to about 330mA. The heat shutdown provides secondary protection. 1 μF to 10 μF 建 Output is recommended to use capacitors. For more details about the output capacitor, see the application information part

Input enable pins: Two digital input pins high input current about 20μA impedance input input threshold and CMOS compatible controller, can Drive CMOS logic from 5V or 3.3V. ESD protects the diode restrictions input to 0.6V underground.

Effective output pin: This pin is the opening of the road set NPN. When the VPOUT pin is adjusted, that is, when the voltage is higher than 11V, connect a 51k -pull -up resistor between the output and the output terminal Power control logic compatible with PCMCIA compatible 5V or 3.3V logic power supply.

VCC detection tube foot: Built -in comparator and 4V benchmark Depending on the voltage detected on the PCMCIA card, the VPOUT is automatically switched from 5V to the 3.3V de socket VCC pin. The input current of the pin is about 30 μA. For only 5V operations, the connection detection pin directly ground. ESD protects the diode restricted input voltage to 0.6V below the ground.

Operation

LT1312 is a programmable output voltage, low -voltage differential stabilizer VPP driver application designed for PCMCIA. The input power is usually obtained at 13V and 20V (for details on the application information on the input power supply). The LT1312 includes the following block: LT1312, a low-voltage differential voltage regulator, is a PNP-based low-voltage differential voltage voltage drop from 13V to 20V to 12V, 5V, 3.3V, 0V or Hi-Z , Specifically depending on the state of two enable inputs and VCC detection inputs. This regulator has a built -in current limit and heat shutdown function to protect the equipment, loads and sockets from accidents to the ground.

ElectricityVoltice control logic: LT1312 has five possibilities

Output mode: 0V, 3.3V, 5V, 12V, Hi-Z, these five modes are selected by two enable inputs and VCCs. enter.

VCC sensor: When the VCC mode is selected, the LT1312 can automatically adjust the adjusted VPP output voltage according to the voltage to 3.3V or 5V on the PC card VCC power pins. The voltage of the threshold comparator is set to 4V to provide about 50mV stagnation to ensure a switch between 3.3V and 5V.

VPP valid comparator: The output voltage when the voltage comparator monitor selects the 12V mode, the drive is low when the output adjustment is more than 11V.

Application information

LT1312 is a voltage programmable linear regulator designed for the application of the PCMCIA VPP driver. The device works in a very low static current (30 μA) in the working mode of 0V and Hi-Z. In Hi-Z mode, the output leakage current drops to 1 μA. The air load should be programmed to 3.3V and 5V, respectively. In addition to the LT1312 has a low static current and a variety of protection functions, it is an ideal choice application for PCMCIA. The LT1312 has a built -in streaming function (330mA) and heat clearance to protect the short -circuit conditions of the equipment and socket VPP pins.

Auxiliary winding power supply

LT1312 provides excellent output, because the adjustment of the input power supply may not be strict. One convenient (economic) power supply is the main system power supply on the main system of the main 5V switch regulator in the auxiliary power supply. LTC #174; 1142HV auxiliary winding power chart 1 is a schematic diagram, which describes the auxiliary winding LTC142HV power system of 5V electromotor with a split 3.3V/5V. The number of turning ratios of 1: 1.8 is used for transformer T1 to ensure that the input voltage LT1312 is between 13V and 20V under all loads. The 9V output of the additional winding is the diode D2 rectification, adding to the main 5V output and the input applied to the LT1312. (Note that the phase of the auxiliary winding must be correct, as shown in Figure 1.) The auxiliary winding reference 5V output from the auxiliary power supply to the DC current feedback 5V segment. By restoring the negative line of C5 to 5V, the exchanges can be improved by the exchanges in response to the exchanges.

When the TTL high -level activation of the 12 -volt output is activated, the LTC142HV segment is forced to be forced to be forced Enter the continuous mode operation. The resistance separator R2, R3, and switch Q3 forced to generate a offset. The offset minus the LTC142HV from the internal offset of the inductive input (pin 14). When the exterior offset cancels the built -in 25 millivoltage offset, the emergency mode TM operation is banned from being forced to enter the continuous mode operation. (Related detailedFor information, see the details of the LTC142HV data table). In this mode, the 14V auxiliary power supply may not consider the effect of load on 5V output LTC142HV.

Continuous mode operation is only 12V in LT1312. If the LT1312 programming is 0V, 3.3V, or 5V, the power supply directly obtains the power supply from the main power (battery pack) through the diode D1. Similarly, the LT1312 output can be loaded in the main 5V output. R4 and C4 absorb the inherent leakage with the T1 second winding and ensure that the auxiliary power supply does not exceed 20V. Figure 2 is the relationship diagram of the output voltage and output current for the auxiliary 14V power supply shown in Figure 1. Please note that when 5V, the auxiliary power supply voltage is slightly high. The output load is too large. This is because the energy flows through the main 5V induction. The circuit in the LTC1142 auxiliary power graph 1 output from 3.3V can be modified to use low battery digits (6 batteries). When the input voltage drops, the 5V duty cycle increases to no enough time from 5V to auxiliary winding. For the application as the 12V load current and the low input voltage ( lt; 6.5V), the auxiliary winding can be derived from the 3.3V segment instead of the 5V segment LTC1142. In this case, a transformer with a number ratio should be used 1: 3.4 to 1: 3.6 to replace the 3.3V part

Application information

] The sensor is shown in Figure 3. MOSFET Q4 and diode D4 have been added, and the diode D1 is no longer used. In the previous circuit, the power supply was obtained directly from the battery to D1. When the LTC1142 was operated by an emergency mode operation, the VPP pin was needed 3.3V or 5V. For these lower input voltage, this technology is no longer effective because the input will be lower than the voltage voltage of the LT1312 regulator. As for this situation, the additional switch Q4 forced switch regulator enters the continuous mode and runs when the continuous mode is selected when 3.3V, 5V or 12V. Line power supply online operation products, such as: desktop computer, special PC card reader/card writing device, medical equipment, testing and measurement equipment, such as a relatively ""primitive"" power supply, such as 5V or 12V power. The 12V power cord on the desktop, the computer is usually too ""dirty"" and cannot be directly applied to the VPP pin of the PCMCIA card insertion. The power switch and load transient may produce voltage peaks that may damage the sensitive PCMCIA flash if the memory card is directly applied to the VPP pin.

Points of Power Card VPP Power Note

PCMCIA compatible flash memory card requires adjustment of 12V VPP programming power to ensure that the internal flash memory circuit is not damaged by the environment. The typical rated values u200bu200bof the flash memory circuit are 13.5V and VPPs that must be kept during all possible loads at the conditions of 12V ± 5%erase and program cycle. Relding voltage will reduce the reliability of the specified flash memory, and overvoltage will damageEquipment 1. The 12V VPP power supply from 5V or 12V generates a 12V VPP power supply of two VPPs is very important to connect to the card without voltage peaks. There should be at the 12V level.

This is easy to realize a local 14V to achieve shown in the figure, from the relatively ""dirty"" 5V or 12V power supply Power supply is in Figure 4 and Figure 5. Accurate voltage control (and further filtering) is provided by the LT1312 drive/regulator. Another advantage of A scheme is that the current limit is increased with the VPP pins to eliminate the power supply when the card socket, the PC card or the switch damage the accident.

Output capacitance

LT1312 is designed to be stable and has a wide range of output capacitors. The minimum recommended value is 1 μF, ESR is 3 #8486; or lower. The capacitor has been connected directly between the output pin and ground, as shown in the middle. For applications with very limited space, capacitors can be used as low as 0.33 μF. The capacitor with a very low ESR ceramic value is less than 1 μF must have a resistance of 2 #8486; as shown in Figure 7 as shown in Figure 7.

Instant and switching performance

LT1312 Design is designed to generate capacitors that produce minimum super -adjusting 1 μF to 10 μF range. The larger capacitor value can be used to slow down and decrease time. The positive output conversion rate determines the current limit and output capacitance by 330mA. A rising time of 0V to 12V is about 40 μs, and the rise time is about 400 μS (see the response curve of the transient typical performance characteristics). From 12V to 0V, the output capacitor settings and a internal drop -down current source is about 30 mAh. The power supply will completely discharge 1 μF capacitor within less than 1ms.

Thermal factors

The power consumed by the device is the sum of the two components: the output current multiplication is used to input and output a differential voltage IOUT × (vin -vout) × vin. The ground pins current can be checked by checking the characteristic part of the ground pins under typical performance. For surface installation equipment, the heat dissipation is a wooden board and its copper traces that use PC's heat dissipation capacity. The knot temperature of LT1312 must be limited at 125 ° C to ensure normal operation. Combined with typical performance charts, use Table 1 to calculate power consumption and mold temperature and ensure that the mold temperature exceeds 125 ° C under any operating conditions.

Calculating knot temperature

Example: If the output voltage is 12V, the input power voltage is 14V, the output current is 100mA, and the highest ambient temperature of A is 50 ° C 50 ° C. What will be the highest temperature BE?

The power consumed by the device is equal to: iOUT × (vs -vpout)+(ignd × vin)

Output u003d 100ma

Vehicle recognition number u003d 14 volts

ignition ignition(IOUT u003d 100MA, VIN u003d 14V) u003d 5mA, so PD u003d 100MA × (14V – 12V)+(5MA × 15V) u003d 0.275W Table 1, thermal resistance should be 120 ° C/W to 131 ° C within the range/W depends on the copper area.So the knot temperature is higher than the ambient temperature

less than or equal to: 0.275W × 131 ° C/W u003d 36 ° C

The highest knot temperature is equal to the increase of the knot temperature exceeding the environmental temperature plus the highest environmentTemperature or: TJ maximum value u003d 50 ° C+36 ° C u003d 86 ° C.