Datasheet

R _ Setpoint 2.3 R _ NTC= ´

bq500410A

SLUSB96 – NOVEMBER 2012

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Shut Down by Thermal Sensor or Trigger

Typical applications of the bq500410A does not require additional thermal protection. This shutdown feature is

provided for enhanced applications and is not limited to thermal shutdown. The key parameter is the 1.0-V

threshold on pin 2. Voltage below 1.0 V on pin 2 causes the device to shut down.

The application of thermal monitoring via a Negative Temperature Coefficient (NTC) sensor, for example, is

straightforward. The NTC forms the lower leg of a temperature dependant voltage divider. The NTC leads are

connected to the bq500410A device, pin 2 and GND. The threshold on pin 2 is set to 1.0 V, below which the

system shuts down and a fault is indicated (depending on LED mode chosen).

To implement this feature follow these steps:

1. Consult the NTC datasheet and find the resistence vs temperature curve.

2. Determine the actual temperature where the NTC will be placed by using a thermal probe.

3. Read the NTC resistance at that temperature in the NTC datasheet, that is R_NTC.

4. Use the following formula to determine the upper leg resistor (R_Setpoint):

(1)

The system restores normal operation after approximately five minutes or if the receiver is removed. If the feature

is not used, this pin must be pulled high.

NOTE

Pin 2 must always be terminated, else erratic behavior may result.

Fault Handling and Indication

The following is a table of End Power Transfer (EPT) packet responses, fault conditions, the duration how long

the condition lasts until a retry in attempted. The LED mode selected determines how the LED indicates the

condition or fault.

Table 5. Fault Handling and Indication

DURATION

CONDITION HANDLING

(before retry)

EPT-00 Immediate Unknown

EPT-01 5 seconds Charge complete

EPT-02 Infinite Internal fault

EPT-03 5 minutes Over temperature

EPT-04 Immediate Over voltage

EPT-05 Immediate Over current

EPT-06 Infinite Battery failure

EPT-07 Not applicable Reconfiguration

EPT-08 Immediate No response

OVP (over voltage) Immediate

OC (over current) 1 minute

NTC (external sensor) 5 minutes

10 seconds LED only,

PMOD/FOD warning 12 seconds 2 seconds LED +

buzzer

PMOD/FOD 5 minutes

Product Folder Links: bq500410A