Features

The complete power path management of the two people

Battery, DC power supply, charger and backup power supply

Compatible

Battery Chemistry

The 3 diodes mode ensure that the power supply can be available

Under cold start conditions

All N channel switching can reduce power Loss

Capacitor and battery swing restrictions

Seamless switching power supply

Two independent charging and monitoring

battery pack

New, small -sized, 36 -drawing SSOP packaging

Application

notebook computer power management

Portable instrument

Handheld terminal

Portable medical equipment

Portable industrial control equipment

Description

LTC #174; 1479 is a heart single battery and dual battery laptop solution for comprehensive power management and other Portable equipment. LTC1479 Control the input from two battery packs and a DC power to the main system switching regulator. It is cooperating with the LTC power management product creation system (LTC1, LTC1, etc.) solutions: starting the source from the battery and DC power supply, and end the complex load at the input end of each computer. The power management provided by the system μP monitoring and actively guided the LTC1479. LTC1479 uses low loss N channel MOSFET switches to guide electricity from three main sources. The adaptive current limit scheme reduces the switch during the conversion of the capacitor and the battery by controlling the grid of MOSFET. LTC1479 directly connects LT1510, LT1511 and LT1620/LTC1435 battery charging circuit

Absolute maximum rated value

DCIN, BAT1, BAT2 power supply voltage 0.3 volt to 32 volts

Perception, perception, VBAT, V+ 0.3 volts to 32 volts

GA, GB, GC, GD, GF, GF, GH, GH 0.3 volts to 42 volts

South African Securities Corporation, SCD, SEF, SG, SH 0.3 volts to 32 volts

switch, VGG 0.3 volts to 42 volts

DCDIV, BDIV 0.3 volt to 5.5 volts

All logic input (Note 1) 0.3V to 7.5V

All logical output (Note 1) 0.3V to 7.5V

VCC adjustmentThe output current. 1 mia

VCCP regulator output current 1 mia

V+output current 1 mAh

VGG regulator output current 100 meters

Work temperature

LTC1479CG 0.c to 70.c

LTC1479ig-40-C to 85-C

Jacking temperature 125 degrees Celsius

Storage temperature range -65 -C to 150-C

Lead temperature (welding, 10 seconds) 300 degrees Celsius

DCTability

Unless otherwise explained, otherwise vdcin 25V, VBAT1 16V, Vbat2 12V, TA 25OC. (Note 2)

DC special characteristics

Unless there are other instructions, otherwise VDCin 25V, VBAT1 16V, VBAT2 12V, TA 25OC. (Note 2)

indicates the standard temperature range suitable for the entire operation.

Note 1: Logic input to protect the diode ground with high impedance CMOS doors with ESD, so it should not be mandatory than grounding. However, these inputs can be driven on the VCCP or VCC power supply, because there are no clamping diode between the input pins and the supply track. This helps run in the 5V/3V hybrid system.

Note 2: The selected operation mode is true table. It defines the operating conditions and logical status operation mode related to each normal , and the characteristic table of the test conditions should be determined with electrical. The actual production test conditions may be stricter.

Note 3: The following input is high impedance CMOS input: 3DM and DCIN/BAT, without internal pull -up current.

Note 4: The following input has a built -in 2 μA upper pull current source (through the series diode): Batsel, Batdis, and Chgsel.

Note 5: Measure the gate opening and close time limit, that is, vSense 0V, in a typical application circuit.

The true value table (selected operation mode)

3dm triangular duct mode. When this mode is called, there is only the first MOSFET switch in each back switch pair, that is, SW A, SW C and SW E. The current can still be used to help restart the system through the diodes of the inherent body idle switch, that is, SW B, SW D, and SW F to help restart the system after encountering abnormal operating conditions. See more details of the sequential map and application information.

Typical performance features

pin function

External power supply foot

DCIN (pin 1): power input. 330 The resistor should be connected in series with this pin and external DC power supply. The 0.1 μF bypass power container should be connected to this other needle closer, the better.

DCDIV (pin 2): The power distributioner input. This is an impedance comparator input (rising edge) with a climax with a 1.215V threshold and about -35mv lag.

BAT1, BAT2 (pin 35, 34): Power input. These two needles are from the input of two batteries. 1 μF bypass capacitors should be connected as close to each pin. If there is no larger battery power capacitor, it may be less than 2 inches.

VBAT (pin 32): battery voltage induction. This needle is connected to the top of the battery resistance elevator to BAT1.

BDIV (pin 33): Battery pressure device input. High impedance has a 1.215V threshold comparator input (drop edge) and about 35mV magnetic stagnation.

VBKUP (pin 36): power input. The input is when the LTC1479 is in the spare operation mode. 1 μF bypass electric container should be connected to the VBKUP pin component. If there is no larger spare power supply, turn off the 2 inner electric container as much as possible. ): Power output. Bypassing this output has at least 0.1 μF capacitors. Thevccp power supply is

is mainly used for internal logic circuit power supply.

VCC (pin 15): Power output. The nominal 3.60V output. Use 2.2 μF to bypass the regulator to output the capacitor. This capacitor is necessary for stability

V+(pin 17): power. V+pins via three DCIN, BAT1 and The internal diode of the BAT2 pin and the top power supply to the top of the VGG switching regulator. Use 1 μF/35V capacitor to bypass the pin.

VGG (pin 16): door power supply. This high voltage (36.5V (36.5V ) The switching regulator is only used to drive the internal micro -power door drive circuit. Do not load this sales to any external circuit. Use 1 μF/50V to bypass the pin capacitor.

SW (pin 18): Output. This sales -driven VGG switch regulator Electrochemical device is between this pin and V+pin.

GND (pin 19): ground. V+V+bypass capacitors should return the connected ground direct ground direct ground To the source transfer device of the N -channel switch in VGG. Input power switch

GA, GB (pin 4, 6): DCIN switch door drive. The door of the two pins drivers with the back of the N channel switch and DCIN Enter the series.

SAB (pin 5): The source returns. The SAB pin is connected to the source of SWA and SWB. A small drop -down current is turned off as a switch.

GC, GD (pin 7, 9): BAT1 switch door drive. The two pins driver's back -to -back N -channel door and BAT1 input the connected switch.

SCD (pin 8): Zhenyuan circuit. SCD pins are connected to the source of SWC and SWD. A small drop -down current as the switch is turned off

GE, GF (plugging 10, 12): BAT2 switch door drive. These two pins drive the door of the back of the back N -channel to enter the connected switch with BAT2.

SEF (pin 11): Zhenyuan circuit. The pin has been connected to the source of SEFSWE and SWF. When a small drop -down current switch, Source restores the potential of this node to 0V.

Sense+(pin 13): The current input into the current. This other needle should be directly connected to the top (switch side) three input power string -value resistors to select switch pairs, SW A/B, SW C/D, and SW E/F, which is used to detect and control power supply and control power supply and control power supply and control power supply. Output capacitance.

Sense - (pin 14): The current input is poured into the current. This other needle should be directly connected to the three input power series low -value resistance selection switch pairs, SW A/B, SW C/D, and SW E/F, which is used to detect and control the power supply and output capacitance for inspiration. Battery charging switch

GG, GH (pin 29, 27): Charger switch door drive. These two pin drives back -to -back N -channel gate output switch pairs, SW G and SW H have two batteries.

SG, SH (pin 28, 26): The source of the shock returns. These two pins are connected to the source of SW G and SW H, respectively. A small drop -down current source returns these nodes to 0 volts when the switch is turned off.

CHGMON (pin 31): battery selector output. This pinch is the output BAT1 and BAT2 connected to the internal switch and connect to the voltage feedback resistor charger circuit selected by the selected battery.

Micro -processor interface

DCINGOOD (pin 25): comparator output. The output of this drainage channel output has an internal 2 μA pull -up current, which is connected to the VCCP power supply through the diode. If there is more pull -up resistance, it is necessary to increase the external pull -up resistance current. When DC power supply voltage is higher than the programming voltage.

Lobat (pin 3): comparator output. This kind of open drain output does not have an internal pull -up current source, and when the selected battery voltage drops, the low level is lower than the programming voltage.

DCIN/BAT (pin 24): Selector input. This high impedanceEye input to connect to DC power supply, based on DCINGOOD pin information. In some minimized systems, the DCIN/BAT pin can be directly connected to DCINGOOD.

BATDIS (pin 23): The battery is disconnected input. This high impedance logic input has a built -in 2 μA upper pull current source and allows μP to disconnect the battery and system.

3DM (pin 22): input of triangular pipe mode. This high impedance logic input does not have a built -in upper pull current source. Connect a 100K resistor from the pin to ground to ensure that the triangle mode operation starting from Cold Start

chgsel (pin 21): The battery charger selector input. This high impedance logic input has a built -in 2 μA upper pull current source, and allows μP to determine to output the battery to the charger through one of the pairs of switches. Switch to the selected battery.)

Batsel (pin 30): battery selector input. This high impedance logic input has a built -in 2 μA upper pull current source and allows μP to select which battery system and battery monitoring comparator input. When choosing a battery 1, the logic of this input is high, and the logic of the battery 2 is low.

operation

LTC1479 is responsible Connect and disconnect without distinction. The switch between the input power supply is smoothly completed, with the help of a low -losses N channel switch, the special door drive circuit battery pack and the system power supply of the swarm of the swarm are provided with a capacitor.

All N channel exchange

LTC1479 drives the external back -to -back N -channel MOSFET switch directly from three main power supply to the power supply: external DC power supply, main battery, and connected to the main power. BAT1 and BAT2. (N -channel MOSFET switch is more cost -effective to provide a lower voltage drop copy than the P channel.)

Gate drive (VGG) power supply

The gate driver of the low loss N channel switch is the grid driver is the grid driver of the N channel switch is the gate driver is Power supply by a micro -power boost regulator, the regulating voltage is about 36.5V. VGG power supply provides a sufficient voltage of three main power supply above 28V working voltage to ensure that the MOSFET switch is fully enhanced. The power of this inductor -based regulator comes from three internal diodes, as shown in Figure 1. The three diode are connected to the three main power sources, DCIN, BAT1 and BAT2. The maximum voltage potential is guided to the top sensor at the top of the voltage regulator to maximize the efficiency of the regulator. C1 provides filtering and installation in a small surface installation package at the top of the 1MH switching electrocomputer L1. The fourth internal diode quotesIt is important to further reduce external parts from 1MH to VGG output capacitors C2. In fact, as shown in the figure 1. VGG only requires three external component regulators, L1, C1, and C2.

Inspirational surge restrictions

LTC1479 uses adaptive wave current to limit the three -person inlet and DC/DC converter input capacitors. The passing voltage measures a small value resistance RSense to determine the three main switching pairs flowing through the three main switching pairs, SW A/B, SW C/D, and SW E/F during the transition period. Figure 2 is the frame diagram switch that only displays the DCIN switch to SW A/B. (The switch is the same for SW's door -driven circuit C/D and SW E/F). The voltage of the two -way current measurement and restriction circuit determines the voltage through the voltage of RSENSE to 200 millivolttil. This corresponding switching gate voltage VGS is restricted during the transition, until the flow is usually faded within a few milliseconds, depending on the input capacitance value according to the DC/DC converter

] Operation

This scheme allows capacitors and MOSFET switches to use different sizes and current rated values u200bu200bwithout circuit modification systems in the same device. After the transition period is over, the MOSFET in the switch selected by the two VG rose to about 6V. The gate driver is set to 6V to provide sufficient current logic -level MOSFET switch over speed gears, which does not exceed its maximum VGS rated value.

Internal power supply

Two internal power supply is the monitoring function of controlling logic power supply. The VCCP logic power supply is about 5 volts, which is most internal logic circuits. The VCC power supply is about 3.60V, which controls the circuit and the door drive for the VGG power switch regulator. The VCC power supply has an under voltage locking circuit. Under the condition that it is completely lost, the power consumption is reduced to a minimum of about 4.5V when all available power supply fails.

DCIN voltage monitoring

DCIN input via two inputs in DCIN pins and DCDIV. The input threshold is 1.215V (ascending edge) about -35mV lag. The use of a clear voltage threshold can ensure that the DC power supply can only be connected to the DC/DC converter input.

Battery voltage monitoring

LTC1479 has the two functional battery packs of independent monitoring. (Therefore, a battery pack may discharge while charging.) The selected battery disk group has dropped to the level of the closed sequence or other battery packs.

Battery charging management function

LTC1479 directly with the LT1510/LT1511 interface battery charger circuit. The double gate -drive circuit controls the two back -back N channel switches pairs, SW G and SW H, control in logic (chgsel)The bottom -connected charger is output to the selected battery pack. Break off and close the movement to ensure that the current does not switch from one battery pack to another battery pack charger output. CHGSEL input also switches the selected battery pack to the top charger system in the top charger system selected by the selected battery pack to pass the CHGMON pins.

The power supply interface of the backup power supply

The power supply of the LTC1479 comes from the supply power source when the backup power supply is not available when the three main power supply is unavailable. The μP of the interface of the supporting microprocessor must provide a comprehensive control of the power management system with the LTC1479. LTC1479 communicates with μP through the following ways: five logical input and two logical outputs are as described in Table 1.

Application information

Power path exchange concept

Power selection

LTC1479 driver low loss switch directly connected to directly connect connect The main power path of the power supply dual charging battery system-in most laptops and other portable devices. Figure 3 is the main characteristic management system of a concept box. LTC1479 dual battery power supply. Start from the three major powers to start the power supply and end point at the system DC/DC regulator. Switch SW A/B, SW C/D, and SW E/F directly encapsulate the input terminal of the DC/DC switching regulator from the AC adapter (DCIN) or one of the two batteries. Switch SW G and SW H to connect the battery pack required for the battery charger. Each of the five switches is directly connected to the power management system by the LTC1479.

Use the [capacitor

The influx of the system DC/DC and the output current regulator input capacitor input capacitors are limited by LTC1479. which is. The conversion of currents from one input power supply to the other input power supply in the capacitor is limited. In many applications, this kind of excitation surge restrictions make the use of low -cost/sizes on the surface of the input end of the DC/DC converter to install capacitors to replace more expensive/larger aluminum electrolytic grooves.

Note: Consult the specific surge specifications and restrictions of capacitor manufacturers, as well as some tests that may be performed to ensure that these restrictions are met under all possible operating conditions.

Back -to -back switch topology

The simple SPST switch shown in FIG. 3 In fact, it is composed of two back -to -back N channel switches. These low losses, the N channel switch is packaged in 8 stitches and SSOP packaging, which can be from many manufacturers. Back -to -back topology eliminates the problem -related power MOSFET switch related to the built -in diodes, allowing each switch to close the current when the two switches are turned off, and the current in any direction has been closed. Back top topology also allows each half of the independent control switch pair, which helps two-way surge restrictions and the so-called 3- diode mode described in the next section.Under the pieces, each switch is turned on and closed at the same time. For example, when the input power supply is turned off from a good DC input (AC adapter) to a good battery pack BAT1, the switch is closed to the two doors of SW A/B, and the switch is opened to the door of the SW C/D. The switch to the back to the back to the backbody diode, SWA/B, blocking the current flow or outflow of DC input connector.

Application information

In the 3 diodes mode, each power supply only has the first half of the path switch, that is, SW A, SW C, and SW E open; the lower half, that is, SW B, SW D, SW F. These three switches are now just three diodes that are connected to the three main input power supply as shown in Figure 4. The power supply diode and maximum input voltage via current input to ensure that the power manager is powered on under starting or abnormal operating conditions. (The lack of locking circuit fails when the V+pin drops to about 4.5 volts).

The initial condition of Cold Start

LTC1479 was designed as a 3 diodes mode. When there is no power supply, all five logical inputs are low and available (including backup system). The 100K resistor from 3DM to the ground to ensure that the input is low at the cold start period. This will cause the main PowerPath to pass the highest voltage to the switch DC/DC converter at the input terminal. Normal operation will continue to confirm that the power supply is good.

Recovery from the uncertain electricity conditions can also assert that the 3 diodes mode (active as low as 3DM input by applying abnormal conditions) exist in the system Own, or the management system μP is resetting or unable to work properly. (See the information about when the μP interface part of the power management μP interface is called 3 diodes mode.)

Component selection

N -channel switch LTC1479 Self -adaptable wave surge restriction circuit allows widely used logic levels N groove MOSFET switch. Multiple dual-low RDS (ON) N-channel switches are installed and packaged on the surface of the 8-lead can provide a very suitable LTC1479 application. Maximum leakage voltage, VDS (MAX), in the three main switch pairs, SW A/B, SW C/D, and SWE/F must be high enough to bear the maximum DC power supply voltage. If the DC power supply is within 20V to 28V, use a 30V MOSFET switch. If the DC power supply is 10V to 18V, and the adjustment is well adjusted, the 20V MOSFET switch is used. Usually, the minimum switch (on) of RDS allows VDS to be maximum. In this way, the heat can be dissipated in the switch, and the overall system efficiency can be increased. In some systems with low current requirements, high switching resistors can be affected, but it should be noted that different power in the switch must not exceed the level of the manufacturer's proposal. Maximum leakage voltage, VDS (MAX), in twoIn the right charger switch, SW G and SW H only needs