HPM10_16 Datasheet, PDF (11/18 Pages) ON Semiconductor – Power Management IC for Hearing Aids

HPM10
HPM10 Working Modes
HPM10 has three working modes represented in the state machine below.
CH_CONN =0
Cradle
Mode
(CM)
Deep
Sleep
(DS)
CH _CONN=1
DS _EN =1
SAFE _MODE =0 _{SAFE_MODE=1}
& CH_CONN =0
& SWIN =1
Hearing
Aid
(HA )
CH_CONN = 1
SAFE_MODE=1 &
CH_CONN=0 &
NO_BUTTON=1
Figure 3. HPM10 State Machine
Deep Sleep Mode: A low power mode with all blocks
turned off. HPM10 can enter Deep Sleep Mode in one of
three ways:
• From Hearing Aid Mode when the host DSP toggles the
DS_EN pin high. An example use−case for this
transition is when a program is running on the host
DSP, that determines that the hearing aid is not being
worn or the measured battery voltage is below a
specified value and puts the system into Deep Sleep
Mode to save power.
• From Hearing Aid Mode when the battery voltage
drops below the EOL set point (VEOL level), for the
battery chemistry actively being used to avoid
irreversible battery damage. This is when VBAT<1.0 V
(for AgZN) or 2.2 V<VBAT<3.0 V (for Lithium−Ion).
This will draw the SAFE_MODE status bit to 0.
• From Cradle Mode when the hearing aid charger is
removed, in case the OTP bit “no_button” is not set.
Cradle Mode: The hearing aid will enter in Cradle Mode
when the hearing Aid is physically connected to Cradle
(CH_CONN=1). In this mode, the hearing aid battery is
being charged.
Once in this state, the following sequence of processes
will occur:
• The OTP is enabled and its contents are copied to
internal latches.
• After the OTP contents have been read, a Cyclic
Redundancy Check (CRC) is made by the controller. If
it fails, the system transitions to completion phase in
Cradle Mode and an error flag is set.
• If the CRC passes, the controller starts the charging
process.
The charging process is controlled by a controller and
firmware in ROM.
Hearing Aid Mode: The hearing aid DSP power is supplied
by HPM10 and there is no digital logic running on HPM10.
In this mode, the hearing aid is in normal operation mode and
receives its supply voltage from HPM10. HPM10 can enter
Hearing Aid Mode in two ways:
• From Deep Sleep after SWIN goes high from a button
press. The battery voltage must be in a valid range.
• From Cradle Mode after removed from Cradle with
OTP bit NO_BUTTON=1. The battery voltage must be
in a valid range.HPM10 is either clocked with the
Hearing Aid Mode Oscillator, or with the divided
EXT_CLK.
The recommended tasks for the host DSP in Hearing Aid
Mode are as follows:
• Set the external clock division ratio (if desired) by
driving the 3 CLKDIV pins (*)
• Apply a valid clock to EXT_CLK pin
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