Dual PowerPath™ Controller Simplifies Power Management Design Note 160 Jaime Tseng As the demand for portable electronics with multiple batteries continues to grow, so does the need for simple and efficient solutions for switching between batteries. The LTC ®1473 simplifies the design of circuitry for switching between two batteries or a battery and an AC adapter.
protection shuts off the gate drive when a fault condition exceeds the user-programmable time limit, inrush current limiting limits the current flowing into or out of the system bypass capacitor and a diode default mode allows power to flow from the highest potential until the inputs can be defined.
The LTC1473 is designed to drive two sets of low loss, back-to-back N-channel MOSFET switches to route power where needed, typically to the input of the main system switching regulator. An internal micropower boost regulator supplies the gate drive for the N-channel MOSFET switches.
Automatic Switchover Between Battery and AC Adapter A protected automatic switchover between a battery and a power source connected at DCIN can be constructed using the circuit in Figure 1. Under normal conditions, this circuit will route the voltage at DCIN to the output.
The LTC1473 simplifies the designer’s task by incorporating a number of protection features. Short-circuit
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and PowerPath is a of Linear Technology Corporation. All other trademarks are the property of their respective owners.
Si4936DY
74C00
13
3
7
6
12 10
MMBD2838LTI 1
11
2 3
8
4
9 1
2 4
5
5
+ 14
R5 500k
CTIMER 4700pF
D3 7.5V
6
C7 1μF
+
7 C8 1μF
L2* 1mH
8
LTC1473 IN1
GA1
IN2
SAB1
DIODE
GB1
TIMER SENSE V+
+
SENSE –
VGG
GA2
SW
SAB2
GND
GB2
16 15 14
RSENSE 0.033Ω
13
OUT
12 11 10 9
*COILCRAFT 1812LS-105XKBC Si4936DY R6 900k 1%
R7 130k 1%
R8 427k 1%
R9 113k 1%
1
LTC1442 OUT A OUT B
2
V–
3
IN A+
REF
IN B –
HYST
4
V+
(DCIN)
8 7 6 5
R10 50k 1% R11 1.132M 1%
C9 0.1μF
(BATTERY)
AC ADAPTER
Figure 1. Protected Automatic Switchover Between Battery and AC Adapter
08/97/160_conv
DN160 F01
with a 500k resistor supplies power for both the CMOS NAND gates and the LTC1442.
If the voltage at DCIN drops below 9.75V, DCIN is deselected and the battery voltage is routed to the output. If the battery voltage is less than 5.9V, each switch is made to mimic a diode, allowing power to flow from the highest potential source to the output. In this “2-diode” mode, the first half of each PowerPath switch pair is turned on, and the second half is turned off. Thus, two diodes are formed by the body diodes of the MOSFET switches that are turned off.
Power Routing Circuit for Microprocessor Controlled Dual Battery Systems The microprocessor controlled dual battery system shown in Figure 2 uses two LTC1473s to provide input power routing and battery charging multiplexing. The two batteries can be of different chemistries. One LTC1473 is used to connect the output of the charger to the battery; the other connects the battery to the input of the system switching regulator.
The inrush current limit of 6A is selected with a 0.033Ω RSENSE resistor. The fault timer is set to 1.1ms with a 4700pF CTIMER capacitor. If a MOSFET switch is in current limit for more than 1.1ms, an internal latch in the LTC1473 is set and the MOSFET switch is turned off.
The power-management microprocessor provides overall control of the power management system in concert with the two LTC1473s and the auxiliary powermanagement systems. The microprocessor decides which battery to connect to the input of the system switching regulator and which battery is in need of recharging. To charge a battery, the microprocessor selects the charging algorithm for that particular battery chemistry.
The LTC1442 shown in Figure 1 is an ultralow power dual comparator with a precision 1.182V reference. This comparator monitors the voltage at DCIN and the battery voltage and selects which MOSFET switch to turn on. Simple logic, comprising CMOS NAND gates, decodes the comparator outputs to control the inputs of the LTC1473. A 7.5V Zener shunt regulator in series Si4963DY
Si4936DY
16 15 14 13 12
RSENSE 0.033Ω
11 10 9
MMBD2838LT1
LTC1473
1 IN1 2 IN2 3 DIODE
GA1 SAB1 GB1 +
TIMER
SENSE –
V+
SENSE
GA2
VGG
SAB2
SW GND
GB2
4
1 750k
2 3
CTIMER 4700pF
CTIMER 4700pF
500k
4
5
5
6
6
7
C7 1μF
8
+
7
+ C8
L1* 1mH
8
LTC1473 IN1
GA1
IN2
SAB1
DIODE
GB1
16 15 14
+ 13
TIMER
SENSE
V+
SENSE –
VGG
GA2
SW
SAB2
GND
GB2
12
RSENSE 0.033Ω
11 10 9
1μF
Si4963DY
*COILCRAFT 1812LS-105XKBC BAT2 8.4V Li-Ion
BAT1 12V NiCd
POWER MANAGEMENT μP
MMBD914LT1
Si4936DY
TO MAIN SWITCHING REGULATOR
SMBus MBRD340 DCIN
1473 F07
BATTERY CHARGER
Figure 2. Power Routing Circuit for Microprocessor Controlled Dual Battery System
Data Sheet Download
www.linear.com
Linear Technology Corporation
For applications help, call (408) 432-1900 dn160f_conv LT/TP 0897 185K • PRINTED IN THE USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900
Design Note 503. Ding Li. Introduction .... of frequent and large load stepsâan important design consideration. Test results ... application. VTT Supply. The VTT ...
The remotely sensed VOUT1 has a voltage regulation ac- curacy of 0.67% ... L, LT, LTC, LTM, Linear Technology, the Linear logo and PolyPhase are registered.
Introduction. The LTC®3838 is a dual output, dual phase buck controller that employs a controlled constant on-time, valley current mode architecture to provide ...
tween operating regions is ideal for automotive, telecom and battery-powered systems. Higher input voltage is easily enabled by adding a high voltage gate ...
Design Note 434. Tick Houk ... today's most demanding power supply applications: high current, low .... For single-output multiphase applications, the LTC3811.
a DC/DC converter solution with high efficiency and small size. The LTC3832 also ... soft-start voltage ramp rate in this circuit is set by CSS. Figure 4 shows the ...
for high performance servers, network and computing systems continues ... L, LT, LTC, LTM, Linear Technology, the Linear logo, Burst Mode and. PolyPhase are ...
in position 2. Multiple LTC2937s can share sequence position information, so that sequence position N happens at the same time for all LTC2937 chips, and.
PowerPath⢠controller that simplifies the design of backup systems. ... Backup Power Application. Figure 1 ... Designing a power backup system is easy with the.
erences selection on the menu bar as shown in Figure 3. Finding Preferences ... libraries have a predefined main() that calls setup() and an infinite loop calling ...
Figure 9 shows a typical charge profile with this wireless power configuration. Actual data will vary with component tolerance and specific setup. Demo Board ...
This could be monitored by the host. Pin. Function. 1 ... external source and depending on the host ..... This is probably best used with the ACK character as this.
into spaces where multichip solutions cannot. Neverthe- ... support of high output currents. The LT3692A fills ... performance to rival that of multichip solutions.
when driving capacitive loads. For each amplifier, the ... Driving Large Capacitive Loads. Though the LT1462/3/4/5 ... Data Sheet Download www.linear.com/ ...
Monitor and Standalone Comparator Block ... into spaces where multichip solutions cannot. ... The LT3692A provides an on-die temperature monitoring function ...
Introduction. The top side of a typical system board, such as a. PCIe card, is densely populated with FPGAs/ASICs/ microprocessors, transceivers, connectors ...
Reliable High Performance Regulation. The LTM4622 features a controlled on-time current mode architecture for a fast transient response and. L, LT, LTC, LTM, ...
150°Câmeets the needs of industrial, automotive, telecom, military, aerospace and distributed systems. The LTC3892's low IQ is indispensable in battery-.
For economic and ecological reasons, the building of new transmission lines and expansion of existing transmission systems are becoming more and more difficult. In this new situation, it is necessary to utilize the existing power transmission system
Introduction. Power dissipation is a significant problem facing the designers of DC/DC converters in industrial and auto- motive applications, where high currents ...
Master/slave channels are enabled via the master's enable pin and regulate to the master's feedback network. Output current can be increased to 3A or 4A by ...
L, LT, LTC, LTM, Linear Technology, the Linear logo PolyPhase, Burst Mode are registered trademarks .... design can achieve high efficiency, small size and low.
