HPM10_16 Datasheet, PDF (12/18 Pages) ON Semiconductor – Power Management IC for Hearing Aids

HPM10
• Periodically monitor pin VHA using its on−board ADC
• Monitor SWOUT to determine button press events
• Monitor the WARN to determine if the hearing aid has
been placed in cradle, in which case the DSP should
shut itself down gracefully before HPM10 cuts the
power to VHA.
• Toggle pin DS_EN to logical high (VHA level), if it
needs to put HPM10 into Deep Sleep Mode
(*): CLKDIV can be configured by the DSP (through GPIO
for example) or through physical connection.
In Hearing Aid Mode, voltage monitoring is used to prevent
turn−on if battery voltage is not acceptable, and to control
the output mode of the VHA supply.
The voltage levels and modes are as follows:
• 1.0 V to 1.5 V The battery type could be AgZn, Zn−Air,
or NiMH. A low impedance switch connects VBAT to
VHA to power the DSP.
• 1.5 to 2.2 V The battery type is likely AgZn. If pin
AGZN_REG_EN=floating, then the VHA voltage is
powered by a 1.5 V regulator. This is to protect those
DSPs that are not able to handle the unregulated AgZn
voltage. For those DSP that can handle maximum
AgZn battery voltages, the pin AGZN_REG_EN=0V
will enable the low impedance switch between VBAT
and VHA.
• 3.0 V and above. The battery type is Li_Ion. VHA is
powered by a divide by 3 step down converter.
VBAT voltages outside of these ranges will not enable the
VHA, and the DSP will not be powered. Note that each of
these thresholds have hysteresis to ensure stable operation.
The following figure indicates how HPM10 monitors
voltage in Hearing Aid Mode.
VHA
VBAT
VHA ZnAir /AgZn regulator disabled
regulator enabled
VHA Li −Ion
2.0
2.2V
1.5V
1.43V
1.0
1.1V
1.05V_
1.0
2.0
1.1V ZnAir 1.65V
1.2V AgZn 2.0V
2.2V
1.0V
3.0
4.0 ^VBAT
Li_Ion (ONLY _LI =0)
4.3V
3.0V ^{Charge Pump 4.3V}
Li_Ion (ONLY _LI =1)
4.3V
Figure 4. Hearing Aid Mode: Voltage Monitoring
www.onsemi.com
12