BlackBerry patent app addresses "battery slump" monitoring, management issues

A new BlackBerry patent application published just yesterday would improve the ability of BlackBerry devices to read voltage levels.The patent app is entitled System and Method for Managing Battery Slump.


A new BlackBerry patent application published just yesterday would improve the ability of BlackBerry devices to read voltage levels.

The patent app is entitled System and Method for Managing Battery Slump.

As we often do when discussing patents, let's read the Abstract first. The Abstract describes:

A system and method for managing battery slump in a battery-powered communications device including: an input configured for receiving battery voltage level information; an output configured for sending a signal for terminating a transmission; and a controller connected to the input and the output and configured to receive the battery voltage level information from the input; monitor the battery voltage level information; and send a signal via the output to terminate a transmission if the battery voltage level information crosses a predetermined threshold during the transmission.

In particular, the system and method may further include an input connected to the controller and configured for receiving a signal indicating when a transmission is beginning or occurring and the controller is further configured to receive and monitor the battery voltage level information only when the transmission is occurring.

You may be wondering why this is necessary. Let's go to the passages in the Patent app that describe why this is so:

Mobile communication devices such as mobile phones, personal data assistants, and the like are generally powered by internal means, such as an internal battery pack. The internal battery pack is an assembly of one or more batteries/cells that typically have a predetermined capacity.

Typically, battery packs can have different termination voltages (associated with full charge) such as 4.2 V and 4.4 V, for example, as well as different charging/discharging characteristics.

As is well understood, the battery pack needs to have a sufficient capacity to operate the mobile communication device under a variety of conditions, including handling the comparatively greater power requirements encountered when transmitting a signal wirelessly.

In transmitting a wireless signal, a mobile communication device generates an internal data signal that is transmitted using a radio transmitter. The data signal is typically a comparatively low frequency signal that is generally referred to as a baseband signal.

The baseband signal is mixed with a carrier signal having a substantially higher frequency to produce a high (e.g. radio) frequency transmission signal. The transmission signal is amplified in one or more stages of an output power amplification block and then applied to a radio antenna to be radiated.

The amplified transmission signal needs to be sufficiently powered so that it is received with appropriate strength and little or no data loss at a remote base station or another communication device.

The amplification stages of the output power amplification block may include a pre-amplification stage and a power amplification stage for producing the amplified transmission signal.

The amplification level of either the pre-amplification stage or the power amplification stage may generally be adjusted depending on the power required for a particular type of signal.

The power amplification stage is powered so that it can produce an amplified transmission signal that has an appropriate instantaneous maximum power for the required transmission.

In wireless communications, there are many cases where the amplified transmission signal is required to have a large dynamic range of power levels. This range is needed in order to accommodate a signal that has a high peak-to-average power ratio (PAPR) or to accommodate different types of signals that may have different desired power levels and different PAPRs.

In these cases, the power amplification stage must be capable of generating an amplified transmission signal such that the highest instantaneous power level desired for any data type or data rate of the baseband data that is present in the amplified transmission signal is always accommodated without saturation or undue distortion.

In conventional power management schemes, the maximum instantaneous power increases with available power supply voltage, such that insufficient supply voltage may induce amplifier saturation and excessive distortion.

As such, the power amplification stage is typically provided with a power supply voltage that is sufficient for accommodating a specified maximum instantaneous power level. For lower power levels, the excess power supplied to the power amplifier is unnecessary and is generally dissipated as heat or otherwise lost.

In wireless devices that are using a battery, the supply current requirements of the amplifier can constitute a heavy drain on the battery. For example, a GSM transmit pulse has a very high current drain on the battery for a time of .about.500 usec and the current can reach .about.2 Amps.

Such a pulse causes the voltage appearing at the power amplifer stage (PA) to "slump" because of battery internal source resistance (ISR) and other printed circuit board (PCB) trace/component resistances.

This battery voltage slump has led to standards that require the PA to operate with a minimum voltage requirement. These standards include, for example, FCC regulations as well as GSM standards with regard to radiated emissions.

However, it is difficult to accurately choose/set the minimum voltage level of the PA, because battery ISR can have a wide range depending on the age of the battery, the temperature at which the battery is operating and the like.

For example, the worst case slump for cold temperatures and an aged battery can be 2-3 times the slump of a newer battery at indoor temperatures. Thus, in order to design a mobile device that is compliant with standards, the worst case slump must be considered and a lower PA operating voltage must generally be assumed in order to meet the "worst case scenario".

The use of a lower PA operating voltage sacrifices effeciency and available power because in conditions where battery slump is better than the worst case, there will be excess power that is dissipated. This results in shorter battery life and lower production yields.

As such, there is a need in the art for an improved method of monitoring and managing battery slump voltage in mobile devices.

Now, let us briefly read through the solution that this Patent application proposes. Figure 5, and its accompanying documentation, tell us what we need to know.


FIG. 5 shows a schematic block diagram of an exemplary embodiment of the slump monitoring system 520. In this embodiment, the slump monitoring system 520 includes an analog to digital converter (ADC) 600, a trigger input 610, a trigger delay 620, one or more analog inputs 630, a control/math block 640, and one or more outputs 650.

The trigger input 610, receives a signal indicating the start of transmission, for example, a system "transmit" signal from the main processor 102, a signal triggering or enabling the amplifier 510, or the like. It is convenient if a signal that is already in use within the mobile device 100 is used as the signal for the trigger delay 620 because this reduces the need for additional trigger circuitry or the like.

Further, the monitoring of the battery slump only during times of high power requirements, such as transmission, reduces the load on the mobile device 100 with regard to power and processing.

The trigger input 610 is connected to the trigger delay 620, which is preferably digitally programmable, and which is further connected to the ADC 600. The trigger delay 620 provides a predetermined delay before sending a signal or signals to activate the ADC 600.

This predetermined delay is provided to allow time for the battery slump to begin to have an impact on the battery voltage after the beginning of the transmission. For example, for an amplifier 510 generating a transmit pulse of approximately 500 .mu.sec, the trigger delay 620 may be set at approximately 200-300 .mu.sec.

The ADC 600 is also connected to the one or more analog inputs 630, which receive a signal or signals related to battery voltage level and provide these signals to the ADC 600. In some embodiments, the battery voltage may be divided or otherwise manipulated so that the signal related to battery voltage (sometimes referred to as a battery voltage signal) meets the input requirements/limitations of the ADC 600.

In some embodiments, the analog inputs 630 may also include readings related to temperature, PA temperature, battery ID resistor, light sensor, or the like.

With the trigger delay 620 appropriately set the ADC 600 receives the battery voltage signal at the appropriate timing within the transmit pulse. It will be understood that, in alternate embodiments, a trigger delay 620 may not be required. However, since battery slump is unlikely to occur at the start of the transmission, some battery and computing capacity can be saved by including the trigger delay 620.

The ADC 600 is further connected to the control/math block 640. Once triggered by the trigger delay 620, the ADC 600 receives battery voltage analog signals from the analog inputs 630 and converts them to digital signals, which are sent to the control/math block 640 for processing.

In the case where more than one analog input 630 is present, the ADC 600 preferably provides multiple inputs/outputs, which may be provided via multiplexing, if necessary. It will be understood that, in alternate embodiments, the analog to digital processing may also be provided external to the slump monitoring system 520 and the slump monitoring system 520 may receive digital inputs related to battery voltage levels directly into the control/math block 640. Further, functions of the control/math block 640 may be performed by other processors, including the main processor 102.

The control/math block 640 receives digital signals from the ADC 600 and processes these digital signals to monitor slump voltage values. For example, the control/math block 640 may monitor minimum or average slump voltage values. In the present embodiment, the control/math block 640 monitors an average value in order to confirm the input values.

The control/math block 640 monitors slump voltage values to determine if the battery voltage level crosses a predetermined threshold, for example reaches a predetermined minimum value (i.e. a minimum threshold), during a transmit pulse.

In some embodiments, the predetermined threshold may be a dynamic parameter that depends on the transmit power level required for a given transmission. For example, if the transmit power level required is lower, the corresponding battery slump would be expected to be lower and the battery 130 could drain further, allowing for longer battery life.

If the battery voltage level crosses the predetermined threshold, the control/math block 640 sends a signal to the main processor 102 to power down the transmitter 152 in order to avoid violation of relevant standards, regulations or the like.

As a non-limiting example, for a transmit pulse of 500 .mu.sec and a trigger delay 620 set at 200 .mu.sec, the control/math block 640 may take approximately 32 measurements at 6 .mu.sec intervals to provide an average reading. If the average reading is less than, for example, approximately 3.4V, a signal is sent via, for example, the output 650 to the main processor 102, which interrupts the transmission and then powers down the transmitter 152. In particular, the transmitter 152 may be powered down in an appropriate manner based on the particular transmission occurring.

For example, if the transmission is a protocol exchange or a short data exchange, the transmitter 152 could be controlled to power down following the exchange rather than powering down immediately.

I know that's not the easiest of reading, but sometimes, complex solutions require complex explanations.