TS-BAT10

TS-BAT10

Documents
Schematic

Overview

The TS-BAT10 is a PC/104 peripheral that contains two 4.2v 2200mA LiPo batteries wired in parallel to provide a high power battery back up system for Technologic Systems' Single Board computers as well as most other PC/104 SBC modules. The TS-BAT10 acts as both a regulator and a battery back up system, accepting from 5VDC to 30VDC and powering the entire PC/104 stack via the 5+VDC pins on the 64-pin PC/104 connector. The batteries are charged via two dedicated LiPo chargers that will charge the batteries until they reach 4.2 volts or for a maximum of a 6 hour charge time. Each battery has an indication of "charging", "charge complete", or "fault", these three states can be read from userspace by the SBC. Each battery can also have a slow 250mA charge current, or a fast charge 500mA current depending on the current source available.

Getting Started

Be sure to remove all power from the system and install a jumper on position 4 (battery backup disable) of the 2x4 pin header to disable battery power before connecting TS-BAT10 to a PC/104 stack. A jumper also needs be installed in one of the three address decode jumper positions.

The TS-BAT10 can be placed at address range PC/104BASE +0x110-0x11F, +0x150-0x15F, or +0x310-0x31F; this is selected by placing a jumper on position 1-3 on the 2x4 pin header. The device has two 8-bit wide registers at the same address, one is read-only, and the other is write-only. These two registers appear on top of each other for the entire length of the device address range as selected by the jumpers described above.

Operation

When a 5VDC-30VDC power supply is initially applied to the TS-BAT10, it will be regulated down to 5VDC and sent down the PC/104 stack. The batteries will not be charging and will be disabled, there should be no LEDs on the TS-BAT10, and the jumper at position four should be removed to allow the battery back up system to be enabled. If the battery back up is enabled, the batteries will take over immediately and power the PC/104 stack if there is no external voltage source provided. The TS-BAT10 implements a boost regulator in order to boost the 4.2VDC provided by the two LiPo batteries to the necessary 5VDC for the PC/104 system. The input regulator for the external power supply requires at least 4.5VDC in order to provide power to the system, between 4.5VDC - 5VDC the boost regulator will bring the voltage up to the proper levels.

Charging

Once the TS-BAT10 is provided at least 4.5VDC, the host SBC can instruct the battery charging ICs to begin their charging cycle. Using the timers is HIGHLY recommended to provide safe charging. The timer on the charging devices is set for 6 hours, if this expires they will immediately stop charging and show a fault. In order to begin a slow charge with the timers enabled, write 0x78 to the TS-BAT10 address space, both red "Charging" LEDs will turn on. This will draw an additional 500mA (250mA for each battery) for the duration of the charge cycle. For a fast charge with the timers enabled, write 0x18 to the TS-BAT10 address space, again both red "Charging" LEDs will come on. This will cause the TS-BAT10 to draw an additional 1A of current from the external power supply (500mA for each battery).

The standard 5VDC @ 1A power supply from Technologic Systems will not be able to provide enough current to do a fast charge as well as provide power to the SBC. If the regulated 5VDC line slumps below 4.5VDC it will be unable to charge the batteries properly and will suspend charging until the proper voltage is available. It is possible to charge one battery at a time, and it may be useful when the power supply cannot handle the high current draw. The charge controllers are intelligent and commands can continually be issued to the controllers to charge the batteries. They have automatic cutoff when the batteries are at the correct voltage. It is recommended to wait until the batteries report they are less than 3.3VDC and then begin a charge cycle. This is highly dependant on the usage requirements and available of external power. Note that the battery charge controllers will not automatically begin a charge cycle, they must be commanded to do so via software.

Disable battery backup power

There are five ways the battery backup functionality of the TS-BAT10 can be disabled. If valid external voltage is applied, if the battery voltage is below 3.1VDC, a jumper in position 4 is installed, a large current draw has occurred and the regulated 5VDC drops below 4.45VDC, or the battery backup is disabled by software. Upon the regulated 5VDC line being powered (either by battery or external power) the battery backup functionality will be enabled.

If the battery back up is disabled via software, the power to the PC/104 system will be cut out if the external input power is cut out. The software disable will reset to its enabled state when external power is re-applied. Power can also be restored to the system via the battery back up by resetting the battery backup circuit (see "Push Button" below).

Battery Notes

LiPo batteries can be severely damaged if the cell voltage drops below 2.3VDC. In order to prevent permanent damage to the cells the battery backup functionality is disabled if the cell voltage drops below 3.1VDC. LiPo batteries hold their nominal voltage (in this case, 4.2VDC) through the length of their charge. The LiPo discharge curve will drop voltage sharply once the cells can no longer provide adequate current. There is low battery detector that can be read to indicate when the cells are down below 3.3VDC. When the cells are less than 3.3VDC the LiPos will only be able to provide stable voltage for minutes at the most. The batteries CANNOT be used until they are charged above 3.1VDC.

Boost Regulator

The boost regulator can provide 4A of current, the batteries can provide that much current, however if that is exceeded under battery operation and the regulated 5VDC line drops below 4.45VDC the batteries will immediately be disabled until the backup circuit is reset (see "Push Button" below) or external power is restored.

SW1/CN1

On the side of the TS-BAT10 a momentary switch is installed. This switch can be read by software (see "Register Layout" above) from the SBC to trigger a custom event. This switch is also used to enable battery backup functionality while power is cut and the battery backup has been disabled (via software, or if theregulated 5VDC dropped below 4.45VDC). Pressing and holding the switch for one second will cause the battery backup to fully take over and provide 5VDC to the PC/104 system.

Jumper Configuration

Jumper	Function
1	Use 0x110 as base
2	Use 0x150 as base
3	Use 0x310 as base
4	Disable battery backup
CN1	Same as SW1.

Register Map

Status Register (Read only)

This register is available at (PC104 base) + (pins 1-3 TS-BAT10 Base) + 0

Bit	Description	Value
7	Push button status (SW1/CN1)	0 = button being pressed
6	Battery under 3.3VDC	Active low
5	5VDC input OK	Active high
4	Battery backup disable jumper	0 = installed
3	Battery 1 charging	Active low
2	Battery 1 charge complete	Active low
1	Battery 2 charging	Active low
0	Battery 2 charge complete	Active low

Note:

bit 0-1 and 2-3 are also used to indicated a fault in charging. If they are both logic 1 (HiZ state) after initiating a charge cycle, either the timer has expired or the thermal cutoff of the batteries has engaged.

Configuration Register (Write only)

Bit	Description	Value
7	Reserved	N/A
6	Battery 2 fast charge (500mA draw)	Active low
5	Battery 1 fast charge (500mA draw)	Active low
4	Battery 2 charge enable	Active high
3	Battery 1 charge enable	Active high
2	Battery 2 charge timer enable	Active low
1	Battery 1 charge timer enable	Active low
0	Software disable battery backup	Active high