M61040FP Просмотр технического описания (PDF) - Renesas Electronics

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M61040FP

Smart battery protection and monitoring IC

Renesas Electronics 

M61040FP

Operation Description

M61040 is developed for intelligent Li-ion battery pack such as SB in SBS. M61040 is suitable for smart battery.

• SBS: Smart Battery System introduced by Intel and Duracell

• SB: Smart Battery which contains 3 or 4 series Li-ion battery cells.

All analog circuits are included to M61040. Therefore pair using with microcomputer such as M37515 and small

additional parts will give various functions such as battery remaining capacity detection. All functions are described as

follows:

1. Voltage detection circuit of each Li-ion battery cells

M61040 can output each battery cell's voltage of 3 or 4 series connection. Built-in buffer amplifier is monitoring

each battery voltage. Microcomputer can adjust the offset voltage.

2. Charge/discharge current detection circuit

In SBS, remaining capacity check function (Gas-gage function) is necessary. To calculate accurate remaining

capacity, microcomputer must get charge/discharge current periodically. Accurate charge/discharge current of

external sense register is monitored by built-in amp. The charge/discharge current is converted to voltage value

through the accurate sense resistor.

Output gain can be controlled by microcomputer. Off-set voltage can be set lower by external parts, therefore

dynamic range of microcomputer's A to D converter will widen.

3. Over current detection circuit

M61040 contains over current detection circuit. The discharging FET is turned off to stop discharging and it

continues for the over current detection delay time (tIOV1) or longer, if the discharging current becomes equal to or

higher than a specified value. It is necessary for safety of Li-ion battery pack. Delay time is set by external capacity

connected to CIN. Also the voltage of CIN shows detection or NOT detection of over current. Over current

detection is controlled independently by this M61040's built-in hardware NOT by microcomputer's software control.

4. Series regulator, reference voltage

M61040 contains low drop out series regulator. Microcomputer in SB does not need any additional voltage regulator,

Max 20 mA/5 V. Also M61040 gives very accurate reference voltage as 4.85 V for Vref voltage for

microcomputer's A to D converter.

5. Reset circuit for microcomputer

Vreg output voltage is checked by reset circuit of M61040. Therefore, lower voltage of Vreg issues RESET signal to

stop mull-function of microcomputer. Also, lower voltage after long time's left issues RESET signal to stop mull-

function of microcomputer. This function is useful for safety of long time's left battery.

When charger is connected to SB, this circuit will check Vreg voltage, so if Vreg voltage is NOT enough high, this

circuit remains low as for RESET signal to microcomputer.

6. Power save function

M61040FP contains power save function to control several supply current.

The function and control method are shown as table 1.

The function of battery voltage detection circuit, charge/discharge detection circuit, over current detection circuit

can be stopped as the need arises.

Table 1

Control Method

Software control

(through serial I/F)

Battery Voltage

Detection Circuit

{

Charge/Discharge

Detection Circuit

{

Over Current

Detection Circuit

{

Each function can be ON/OFF separately.

REJ03F0237-0200 Rev.2.00 Mar 18, 2008

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