Fezahn The product is appropriate for new designs but newer alternatives may exist. Evaluation Kit Manuals 1. It is important to note the scheduled dock date on the order entry screen. Pricing displayed for Evaluation Boards and Kits is dagasheet on 1-piece pricing. The Sample button will be displayed if a model is available for web samples. Transit times from these sites may vary.
|Published (Last):||10 October 2011|
|PDF File Size:||6.20 Mb|
|ePub File Size:||11.51 Mb|
|Price:||Free* [*Free Regsitration Required]|
For applications with a wall adapter or other auxiliary power source, the load is automatically disconnected from the battery when the auxiliary source is connected.
Two or more LTCs may be interconnected to allow load sharing between multiple batteries or charging of multiple batteries from a single charger. The wide supply operating range supports operation from one to six Li-Ion cells in series.
The low quiescent current 11? A typical is independent of the load current. This pin may also be used to indicate to a microcontroller that an auxiliary supply is connected. Current into a pin is positive and current out of a pin is negative. All voltages are referenced to GND, unless otherwise specified. SENSE is set at SENSE is stepped from A TIME?
Supplies power to the internal circuitry and is one of two voltage sense inputs to the internal analog controller The other input to the controller is the SENSE pin. This input is usually supplied power from a battery or other power source which supplies current to the load. This pin can be bypassed to ground with a capacitor in the range of 0. F to 10? F if needed to suppress load transients.
GND Pin 2 : Ground. Provides a power return for all the internal circuits. A high input also forces the STAT pin to sink 10? If the STAT pin is used to control an auxiliary Pchannel power switch, then a second active source of power, such as an AC wall adaptor, will be connected to the load see Applications Information. An internal current sink will pull the CTL pin voltage to ground logical low if the pin is open.
The STAT pin will then go from an open state to a 10? Supplies power to the internal circuitry and is a voltage sense input to the internal analog controller The other input to the controller is the VIN pin. This input is usually supplied power from an auxiliary source such as an AC adapter or back-up battery which also supplies current to the load.
The terms primary and auxiliary are arbitrary and may be changed to suit the application. Operation begins when either or both power sources are applied and the CTL control pin is below the input low voltage of 0. The dynamic pull-down current of 50? The system is now in the forward regulation mode and the load will be powered from the primary supply.
For a clean transistion, the reverse turn-off threshold has hysteresis to prevent uncertainty. The system is now in the reverse turn-off mode. Power to the load is being delivered through the external diode and no current is drawn from the primary supply.
The external diode provides protection in case the auxiliary supply is below the primary supply, sinks current to ground or is connected reverse polarity. During the reverse turn-off mode of operation the STAT pin will sink 10? Note that the external MOSFET is wired so that the drain to source diode will momentarily forward bias when power is first applied to VIN and will become reverse biased when an auxiliary supply is applied.
A of current if connected. This feature is useful to allow control input switching of the load between two power sources as shown in Figure 4 or as a switchable high side driver as shown in Figure 7. The maximum allowable drain-source voltage, VDS MAX , must be high enough to withstand the maximum drainsource voltage seen in the application. Achieving forward regulation will minimize power loss and heat dissipation, but it is not a U necessity.
If a forward voltage drop of more than 20mV is acceptable then a smaller MOSFET can be used, but must be sized compatible with the higher power dissipation. Voltage droop can occur at the load during a supply switchover because some time is required to turn on the MOSFET power switch.
Droop can be made insignificant by the proper choice of COUT, since the droop is inversely proportional to the capacitance. F to 47? Caution must be exercised when using multilayer ceramic capacitors. Because of the self resonance and high Q characteristics of some types of ceramic capacitors, high voltage transients can be generated under some start-up conditions such as connecting a supply input to a hot power source.
Refer to Application Note This should be checked with each power source as well. R drops in the power path. Both pins are protected from negative voltages. It is usually connected to a resistor whose other end connects to a voltage source. During this mode of operation the STAT pin will sink 10? This will result in a voltage change across the resistor, depending on the resistance, which is useful to turn on an auxiliary P-channel MOSFET or signal to a microcontroller that an auxiliary power source is connected.
External leakage 8 U currents, if significant, should be accounted for when determining the voltage across the resistor when the STAT pin is either on or off. During normal operation, the CTL pin can be biased at any voltage between ground and 28V, regardless of the supply voltage to the LTC The high input also forces the STAT pin to sink 10?
Protection Most of the application circuits shown provide some protection against supply faults such as shorted, low or reversed supply inputs. The fault protection does not protect shorted supplies but can isolate other supplies and the load from faults. A necessary condition of this protection is for all components to have sufficient breakdown voltages. In some cases, if protection of the auxiliary input sometimes referred to as the wall adapter input is not required, then the series diode or MOSFET may be eliminated.
Internal protection for the LTC is provided to prevent damaging pin currents and excessive internal self heating during a fault condition. This feature allows for reverse-battery condition without current drain or damage.
This internal protection is not designed to prevent overcurrent or overheating of external components. Each of these will automatically connect the higher supply voltage, after accounting for certain diode forward voltage drops, to the load with application of the higher supply voltage. Figure 1 illustrates an application circuit for automatic switchover of a load between a battery and a wall adapter or other power input. The system is now in the low loss forward regulation mode.
The STAT pin will then sink current indicating an auxiliary input is connected. The battery is now supplying no load current and all the load current flows through the Schottky diode. A silicon diode could be used instead of the Schottky, but will result in higher power dissipation and heating due to the higher forward voltage drop. Figure 3 illustrates an application circuit for the automatic switchover of a load between a battery and a wall adapter in the comparator mode.
It also shows how a battery charger can be connected. A possible disadvantage is if the auxiliary input ramps up slow enough the load voltage will initially droop before rising. The factors that determine the magnitude of the voltage droop are the auxiliary input rise time, the type of diode used, the value of COUT and the load current.
Ideal Diode Control with a Microcontroller Figure 4 illustrates an application circuit for microcontroller monitoring and control of two power sources.
With a logical low input on the CTL pin, the primary input supplies power to the load regardless of the auxiliary voltage. When CTL is switched high, the auxiliary input will power the load whether or not it is higher or lower than the primary power voltage. Once the auxiliary is on, the primary power can be removed and the auxiliary will continue to power the load. Sufficient capacitance on the load and low or no capacitance on VIN will help ensure this.
Load Sharing Figure 5 illustrates an application circuit for dual battery load sharing with automatic switchover of load from batteries to wall adapter. Whichever battery can supply the higher voltage will provide the load current until it is discharged to the voltage of the other battery. The load will then be shared between the two batteries according to the capacity of each battery. The higher capacity battery will provide proportionally higher current to the load.
When a wall adapter input is applied, both MOSFETs will turn off and no load current will be drawn from the batteries. The STAT pins provide information as to which input is supplying the load current. This concept can be expanded to more power inputs. Whichever battery has the lower voltage will receive the charging current until both battery voltages are equal, then both will be charged. When both are charged simultaneously, the higher capacity battery will get proportionally higher current from the charger.
For Li-Ion batteries, both batteries will achieve the float voltage minus the forward regulation voltage of 20mV. This concept can apply to more than two batteries. The STAT pins provide information as to which batteries are being charged. This allows complete control for disconnection of the charger from either battery. However, no responsibility is assumed for its use.
Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. U High Side Power Switch Figure 7 illustrates an application circuit for a logic controlled high side power switch. Note that if the load is powered from another source, then the drain-source diode can forward bias and deliver current to the power supply connected to the VIN pin.
LTC4412 charger issue
For applications with a wall adapter or other auxiliary power source, the load is automatically disconnected from the battery when the auxiliary source is connected. Two or more LTCs may be interconnected to allow load sharing between multiple batteries or charging of multiple batteries from a single charger. The wide supply operating range supports operation from one to six Li-Ion cells in series. The low quiescent current 11?
LTC4412 DATASHEET PDF
Tejora For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. Please consult the datasheet for more information. Product Lifecycle Production At least one model within this product family is in production and available for purchase. Pin Count is the number of pins, balls, or pads on the device. This pin may also be used to indicate to a microcontroller that an auxiliary supply is connected.