Application Note - EM850X Storage Elements STS/LTS Supervising

EM MICROELECTRONIC - MARIN SA
608003
Application Note 608003
Title:
STORAGE ELEMENTS STS/LTS SUPERVISING
Product Family:
EM850X
Part Number:
EM8500
Keywords:
Harvesting, Solar, TEG, MPPT, Configuration, Setup, Super capacitors, Secondary Battery, Primary
Battery
ABSTRACT
The EM8500 offers a NVM containing all the configuration
parameters. This document describes how to setup the
registers in NVM linked to the storage elements connected to
STS & LTS:
•
Type of battery: rechargeable (secondary battery) or
non-rechargeable (primary battery)
•
Under voltage protection enabled or disabled
•
Voltage level detection:
o
maximum/minimum battery level settings
o
maximum application voltage
•
Voltage measurement timing settings
ABBREVIATIONS
NVM
MCU
STS
LTS
HRV
TEG
MPP
Vmpp
Vov
BAT_LOW
HRV_LOW
VLD
Vref
Vlvl
Vbat
VSUP
VAUX[i]
Csup
Caux[i]
Non-Volatile-Memory
Microcontroller Unit
Short term storage element (capacitor connected to VDD_STS)
Long term storage element (rechargeable battery connected to VDD_LTS)
Harvester, main source of energy (solar or TEG)
Thermal Electrical Generator
(Maximum Power Point) This operating point is reached when the harvester delivers the
maximum power (Pmpp) in a given condition
HRV output voltage at MPP
HRV open voltage (when the EM8500 DCDC converter is disabled)
Flag indicating that the battery is in under-voltage condition
Flag indicating that the HRV is under the minimum power level (HRV low mode when at 1)
Voltage Level Detector
Voltage level detector reference level
Voltage level detector LSB (71.88mV)
Battery voltage connected to VDD_LTS
Main output supply for application
2 independent auxiliary supplies for application
Decoupling capacitor on VSUP
3 decoupling capacitors on VAUX[i]
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SCOPE
The EM8500 addresses two main types of mass storage elements connected to LTS:
1. Rechargeable
a. secondary battery
b. or super capacitor
2. Non-rechargeable for battery life time enhancement (so called primary cell mode)
a. primary battery
On STS side, a standard capacitor in the range of 10uF to few 100uF is connected.
The EM8500 has several registers to setup the storage elements supervising:
1. Type of LTS used
2. Under and over voltage protection level of LTS settings
3. Regulation voltage level of STS when disconnected from LTS
4. Period of voltages measurement settings
The following registers are involved for that action:
Register name
Address
Description
prim_cell_connect: force the connection of STS to LTS in primary cell
mode when at ‘1’
reg_lts_cfg
0x06
prim_cell: set the device in primary cell mode when ‘1’
no_bat_protect: under voltage protection disabled when at ‘1’
Absolute maximum voltage level of the battery
reg_v_bat_max_hi
0x07
Maximum voltage of the battery, form an hysteresis with v_bat_max_hi
reg_v_bat_max_lo
0x08
reg_v_bat_min_hi_dis
0x09
reg_v_bat_min_hi_con
0x0A
reg_v_bat_min_lo
0x0B
Minimum battery and application voltage when STS and LTS are
disconnected, form an hysteresis with v_bat_min_lo
Minimum battery and application voltage when STS and LTS are
connected, form an hysteresis with v_bat_min_lo
Absolute minimum value of the battery and the application
reg_v_apl_max_hi
0x0C
Absolute maximum voltage of the application
reg_v_apl_max_lo
0x0D
reg_t_sts_period
0x02
reg_t_lts_period
0x03
reg_t_hrv_low_cfg
Maximum voltage of the application, form an hysteresis with
v_apl_max_hi
Period between two voltage level measurements of STS, used only
when STS and LTS are disconnected
Period between two voltage level measurements of LTS
t_lts_hrv_low_period: Define the period between two voltage level
measurements of LTS in HRV low mode
Table 1: List of Registers Related to Storage Elements Supervising
0x17
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The default value after reset or start-up of the registers listed in Table 1 is contained in a NVM memory at the
following related addresses:
Register name
Register
Related address in NVM
Address
eeprom6
0x46
reg_lts_cfg
0x06
reg_v_bat_max_hi
0x07
eeprom7
0x47
reg_v_bat_max_lo
0x08
eeprom8
0x48
reg_v_bat_min_hi_dis
0x09
eeprom9
0x49
reg_v_bat_min_hi_con
0x0A
eeprom10
0x4A
reg_v_bat_min_lo
0x0B
eeprom11
0x4B
reg_v_apl_max_hi
0x0C
eeprom12
0x4C
reg_v_apl_max_lo
0x0D
eeprom13
0x4D
reg_t_sts_period
0x02
eeprom2
0x42
reg_t_lts_period
0x03
eeprom3
0x43
reg_t_hrv_low_cfg
0x17
eeprom23
0x57
Table 2: Mapping of Registers in EEPROM
Note: offset between the register addresses and related address in NVM is 0x40
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SUPERVISING REGISTERS SETTINGS SEQUENCE
We advise calculating the different parameters in the following order:
1. Chapter 4: The operating mode: rechargeable battery, primary cell mode, battery protection (reg_lts_cfg)
2. Chapter 5: The absolute min/max voltages (reg_v_bat_max_hi, reg_v_apl_max_hi, reg_v_bat_min_lo)
3. Chapter 6: The capacitor value connected on VDD_STS (Csts).
4. Chapter 7: The VDD_STS supervisory period Tsts_period (reg_t_sts_period)
5. Chapter 0: The v_bat_min hysteresis (reg_v_bat_min_hi_dis, reg_v_bat_min_hi_con)
6. Chapter 9: The value of v_apl_max_lo (reg_v_apl_max_lo)
7. Chapter 10: The value of v_bat_max_lo (reg_v_bat_max_lo)
8. Chapter 11: The VDD_LTS supervisory period Tlts_period and Tlts_hrv_low_period (reg_t_lts_period,
reg_t_hrv_low_cfg)
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VLD REFERENCE
The VLD is used to compare the current state of the voltages VDD_STS or VDD_LTS with a selected reference.
The following registers select the references related to a voltage level:

reg_v_bat_max_hi: reference v_bat_max_hi

reg_v_bat_max_lo: reference v_bat_max_hi

reg_v_bat_min_hi_dis: reference v_bat_min_hi when VDD_STS & VDD_LTS are disconnected

reg_v_bat_min_hi_con: reference v_bat_min_hi when VDD_STS & VDD_LTS are connected

reg_v_bat_min_lo: reference v_bat_min_lo

reg_v_apl_max_hi: reference v_apl_max_hi
 reg_v_apl_max_lo: reference v_apl_max_lo
These registers set the related reference level as follows:
Vref  Vlvl  reg  1
Equation 1: VLD Reference Calculation
The precision of Vlvl is as follows:
Vlvl
MIN(1)
TYP
MAX(1)
69 mV
73 mV
76.2 mV
Table 3: Vlvl Precision
(1) These values are based on a typical spread of voltage level detector.
If the reference level is the maximum value of the hysteresis (_hi), the maximum value of Vlvl is used to calculate
the related register.
If the reference level is the minimum value of the hysteresis (_lo), the minimum value of Vlvl is used to calculate the
related register.
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OPERATING MODE SETTINGS
4.1
Battery type
The first step is to set the type of battery used:

Rechargeable (secondary cell battery; reg_lts_cfg.prim_cell = ‘0’)

Non-rechargeable (primary cell battery; reg_lts_cfg.prim_cell = ‘1’)
4.2
Battery protection
By default the EM8500 checks the under voltage condition of the battery. It is possible to disable this function by
setting the register reg_lts_cfg.no_bat_protect to ‘1’. In this condition, the EM8500 will try indefinitely to start-up on
the battery voltage. If there is no energy from the HRV, the EM8500 will start-up by connecting VDD_LTS to
VDD_STS, execute the boot sequence, as VDD_LTS is lower than v_bat_min_lo it will disconnect VDD_STS and
VDD_LTS, then VDD_STS will collapse and enter in power on reset. Therefore, the EM8500 will start-up again and
loop in this sequence until energy is back from the HRV.
Note: We advise to avoid setting reg_lts_cfg.no_bat_protect to ‘1’ with a rechargeable battery; it can damage the
battery. It is preferable to do it only with a super capacitor.
4.3
Force connection of LTS to STS in primary cell mode
The register reg_lts_cfg.prim_cell_connect forces the connection of LTS to STS in primary cell mode
(reg_lts_cfg.prim_cell = ‘1’). If this bit is set to ‘1’ in the NVM (address 0x46), the connection will be effective after
the start-up sequence. This bit has no effect when reg_lts_cfg.prim_cell = ‘0’ or if VDD_LTS is lower than
v_bat_min_lo.
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ABSOLUTE VALUES SETTINGS
There are 3 absolute values to set up in the EM8500:
1. The maximum battery voltage: v_bat_max_hi
2. The maximum application voltage: v_apl_max_hi
3. The minimum battery voltage (considered also as minimum application voltage): v_bat_min_lo
5.1
Maximum battery voltage
This is the absolute overvoltage limit of the battery. When the supply VDD_LTS reaches this voltage, the EM8500
stops charging the battery. The register reg_v_bat_max_hi defines the absolute maximum battery voltage and is
calculated as follows:
 v_bat_max_hi 
reg_v_bat_max_hi  trunc
 1  1
 maxVlvl 

Equation 2: reg_v_bat_max_hi Calculation
5.2
Maximum application voltage
This level is used when the maximum battery voltage is higher than the voltage the application can afford. If
VDD_STS is higher than this level, the EM8500 will automatically enable the LDO connected on VSUP to protect
the application against overvoltage. The register reg_v_apl_max_hi defines the absolute maximum application
voltage and is calculated as follows:
 v_apl_max_hi 
reg_v_apl_max_hi  trunc
 1  1


max
V
lvl


Equation 3: reg_v_apl_max_hi Calculation
If the application maximum voltage is higher than the maximum battery voltage, reg_v_apl_max_hi shall be set to
0x3F and reg_v_apl_max_lo shall be set to 0x3E. In this condition these two registers will be ignored.
5.3
Minimum battery voltage
The absolute under voltage condition level of the battery is v_bat_min_lo. When VDD_LTS is below that level, the
battery is in protected mode and the flag BAT_LOW stays at ‘1’ until VSUP is on. In that condition it is impossible to
use the battery as source of energy, only the harvester can supply the application. The register reg_v_bat_min_lo
defines this level as follows:
 v_bat_min_lo 
reg_v_bat_min_lo  trunc
 1


min
V
lvl


Equation 4: reg_v_bat_min_lo Calculation
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SHORT TERM STORAGE CAPACITOR SETTING
If the application is supposed to always run on LTS (VDD_STS always connected to VDD_LTS), we advise to use
Csts= 10uF. But if STS supplies the application without the help of the battery or super capacitor, as it is the case
in primary cell mode, the value of Csts shall be carefully calculated.
When VAUX[i] or VSUP is enabled, the decoupling capacitors Caux[i] or Csup is suddenly connected to Csts.
Therefore the transfer of charges from Csts to the decoupling capacitor leads to a drop on VDD_STS. We advise to
avoid a drop higher than 10% of VDD_STS.
Thus, Csts shall be 10 times bigger than the total amount of decoupling capacitors enabled in the same time.
For instance if VSUP and all VAUX[i] are enabled in the same time:
CSTS  10  CSUP  C AUX [ 0 ]  C AUX [1]  C AUX [ 2] 
Equation 5: Csts Calculaton; all Decoupling Capacitors Enabled Together
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STS SURVEY PERIOD
The survey period affects the power loss of the VLD during the measurement of STS. Longer this period, lower the
power loss. The register reg_t_sts_period is a number of t_frame of 1ms and is calculated as follows:
9
vld
sts _ period
in_min
loss
in_min
loss
T

P  t _ frame
3 10

4 P
VLD
4 P
VLD
Equation 6: STS Survey Period Calculation
The parameter Pvld (in [W]) is the power dissipated by the VLD when enabled: 3uW (constant)
The parameter t_frame (in [s]) is the minimum period between 2 measurements: 1ms (constant)
The parameter Pin_min (in [W]) is the minimum power the EM8500 can harvest before entering in HRV_LOW
mode.
The parameter VLDloss (without unit) is the rate of power the user accepts to lose in the VLD measurement of
VDD_STS.
Important note: when VDD_STS is connected to VDD_LTS Tsts_period is not used anymore. The supervisory
period is set by Tlts_period instead (see chapter 11). Therefore, there is no VLDloss due to STS measurement in
that condition.
The register reg_t_sts_period shall be selected according to the following table to be the closest to Tsts_period:
reg_t_sts_period
Tsts_period
000
1ms
001
2ms
010
8ms
011
16ms
100
32ms
101
64ms
110
128ms
111
256ms
Table 4: Tsts_period Related Registers Selection
7.1
Example of STS survey period calculation
Considering that the EM8500 has been configured to stop harvesting energy when the input power is below 2uW:
Pin_min = 2uW
We accept to lose 1% of power in the VLD measurement of VDD_STS: VLDloss = 0.01
Tsts _ period
3 10 9
3


37
.
5

10
4  2 10 6  0.01
Equation 7: Example of STS Survey Period Calculation
According to the Table 4, the closest value to 37.5ms is 32ms, corresponding to reg_t_sts_period = “100”. In that
condition the power loss in the VLD would be about 1.2%.
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HYSTERESIS ON V_BAT_MIN SETTINGS
The voltage level v_bat_min_hi defines an hysteresis with v_bat_min_lo. It has a particular importance to
supervise STS when VDD_STS and VDD_LTS are disconnected; in primary cell mode or when VDD_LTS falls
below v_bat_min_lo.
8.1
Level v_bat_min_hi with VDD_STS and VDD_LTS disconnected
The level v_bat_min_hi is set by the register reg_v_bat_min_hi_dis when VDD_STS and VDD_LTS are
disconnected. When the EM8500 DCDC converter does not charge Csts and VDD_STS and VDD_LTS are
disconnected, Csts is the only source of energy for the application. Depending on the current consumption of the
application in that condition, Csts will drop more or less quickly. If VDD_STS falls below the level v_bat_min_lo,
the EM8500 will stop supplying the application; it will disable VSUP and VAUX[i]. As soon as the VLD measures
VDD_STS below v_bat_min_hi_dis, the EM8500 DCDC converter is enabled to recover VDD_STS as shown in
the following figures:
Figure 1: VDD_STS Measurement Toward v_bat_min_hi_dis
The voltage difference between v_bat_min_hi_dis and v_bat_min_lo shall be higher than the voltage drop
on VDD_STS between 2 Tsts_period with the maximum current consumption. The following equation
calculates v_bat_min_hi_dis:
v_bat_min_hi_dis 
2  Tsts _ period  I max
Csts
 v_bat_min_lo
Equation 8: v_bat_min_hi_dis Calculation
Imax (in [A]) is the maximum current consumption on application side.
Tsts_period (in [s]) is the period between 2 VDD_STS VLD measurements defined in chapter 7.
Csts (in [F]) is the capacitor connected to VDD_STS.
8.2
Example of v_bat_min_hi_dis calculation
Considering that Tsts_period is 32ms, Csts is 100uF, the maximum consumption of the application is 1mA and the
absolute minimum battery voltage is 1.2V. According to the Equation 8, the value of v_bat_min_hi_dis shall be at
least 1.84V.
The register reg_v_bat_min_hi_dis is calculated as follows:
 v_bat_min_hi _ dis 
reg_v_bat_min_hi_dis  trunc
 1  1
maxVlvl 


Equation 9: Register reg_v_bat_min_hi_dis Calculation
In our example the value of reg_v_bat_min_hi_dis = 24 (0x18 in hexadecimal)
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8.3
Level v_bat_min_hi with VDD_STS and VDD_LTS connected
The level v_bat_min_hi is set by the register reg_v_bat_min_hi_con when VDD_STS and VDD_LTS are
connected. This level defines a hysteresis with v_bat_min_lo. As LTS has a huge capacity compare to Csts, this
parameter is less crucial than v_bat_min_hi_dis. This hysteresis delimitates the VDD_LTS voltage range wherein
the flag BAT_LOW is set to ‘1’ before stopping the supply of the application (disabling VSUP and VAUX[i]).
The difference between v_bat_min_hi_con and v_bat_min_lo is depending on the battery discharge curve. There
is only one strict rule:
reg_v_bat_min_hi _ con  reg_v_bat_min_lo  1
Equation 10: reg_v_bat_min_hi_con Toward reg_v_bat_min_lo Conditions
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LEVEL V_APL_MAX_LO SETTINGS
As already written in chapter 5.2, the levels v_apl_max_lo and v_apl_max_hi shall be set to 0x3F if the
application can afford the absolute maximum battery voltage. In that condition, these two levels are ignored. If it is
not the case, and if VDD_STS and VDD_LTS are disconnected, the level v_apl_max_lo calculation shall fulfill 2
conditions:
1. The difference between v_apl_max_lo and v_bat_min_hi_dis shall be enough high to let the EM8500
DCDC charging LTS a minimum of time.
2. The hysteresis between v_apl_max_lo and v_apl_max_hi shall be enough high to ensure VDD_STS will
never rise above v_apl_max_hi.
9.1
Level v_apl_max_lo toward v_bat_min_hi
When VDD_LTS and VDD_STS are disconnected, the EM8500 DCDC charges alternatively STS and LTS. When
the VLD detects that STS reached v_apl_max_lo, the EM8500 DCDC stops charging STS and starts charging
LTS. In that condition STS is the only source of energy of the application. It drops down to v_bat_min_hi_dis and
then the EM8500 charges back STS. To charge the battery in an efficient way, the period during which the EM8500
DCDC charges LTS shall be as long as possible.
Figure 2: Effect of v_apl_max_lo Level on VDD_LTS Charge Phase Period
Considering Tlts_charge_min is the minimum period we want to guarantee, the condition v_apl_max_lo level shall
fulfill toward v_bat_min_hi_dis is the following:
v_apl_max_lo 
Tlts_charge_min  I max
Csts
 v_bat_min_hi _ dis
Equation 11: v_apl_max_lo toward v_bat_min_hi_dis Condition
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9.2
Level v_apl_max_lo toward v_apl_max_hi
When the EM8500 DCDC charges STS at full power, VDD_STS rising edge can be sharp and therefore,
depending on Tsts_period, rise above v_apl_max_hi if there is not enough hysteresis between v_apl_max_lo and
v_apl_max_hi.
Figure 3: VDD_STS Measurement Toward v_apl_max_lo
The sharpness of VDD_STS rising edge is depending on the maximum power the EM8500 DCDC can harvest. To
have enough margins, we consider that the EM8500 DCDC has an ideal efficiency of 100%. When the EM8500
DCDC converter charges STS, the maximum power that the EM8500 DCDC can deliver is limited even if the HRV
can potentially deliver more power (when charging LTS there is no such limitation). The maximum power Pin_max
that the DCDC converters can deliver to STS depends mainly on Vmpp in best case conditions, meaning at
maximum luminescence for a solar cell for instance. Pin_max is calculated as follows:
Pin_max  6.65 103 Vmpp2
Equation 12: Pin_max Caclulation
Note: the chapter 2 of the document e8500_app_note_hrv_param.pdf describes how to calculate Vmpp.
The level v_apl_max_lo shall fulfill the following equation to ensure VDD_STS will never rise above v_apl_max_hi
when the DCDC converter charges STS.
v_apl_max_lo  v _ apl _ max_ hi 2 
4  Tsts _ period  Pin_max
Csts
Equation 13: v_apl_max_lo toward v_apl_max_hi Condition
9.3
Level v_apl_max_lo adjustment
The level v_apl_max_lo shall fulfill both Equation 11 and Equation 13. If it is not the case, there are two main ways
to correct it:
1. Reduce Tsts_period: it impacts the efficiency at very low power range; it is in the majority of the cases
negligible. The value of VLDloss shall be reconsidered in Equation 6.
2. Increase Csts: it can impacts the mechanical size of the component and its cost. The solution 1 is preferable.
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9.4
Level v_apl_max_lo with VDD_STS and VDD_LTS connected
If VDD_LTS and VDD_STS are always connected, the calculation of v_apl_max_lo is less critical and shall only
fulfill the following rule:
reg_v_apl_max_lo  reg_v_apl_max_hi  1
Equation 14: reg_v_apl_max_lo toward reg_v_apl_max_hi Condition
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10 LEVEL V_BAT_MAX_LO SETTINGS
If the application can afford the maximum battery voltage, v_apl_max_lo and v_apl_max_hi are set to 0x3F and
respectively 0x3E and not used. In that case, the conditions defined by the Equation 11 and Equation 13 shall be
applied to v_bat_max_lo as follows:
Tlts_charge_min  I max
Csts
 v_bat_min_hi_dis  v_bat_max_lo  v_bat_max_hi 2 
4  Tsts _ period  Pin_max
Csts
Equation 15: v_bat_max_lo Conditions; v_apl_max_lo and v_apl_max_hi not Used
If both conditions of Equation 15 cannot be fulfilled, the corrective actions are the same then the one defined in
chapter 9.3.
10.1 Level v_bat_max_lo with VDD_STS and VDD_LTS connected
If VDD_LTS and VDD_STS are always connected or if v_apl_max_lo and v_apl_max_hi are used, the
calculation of v_bat_max_lo is less critical and shall only fulfill the following rule:
reg_v_bat_max_lo  reg_v_bat_max_hi  1
Equation 16: reg_v_bat_max_lo toward reg_v_bat_max_hi Condition
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11 LTS SURVEY PERIOD
As LTS is huge compare to STS, the LTS survey period Tlts_period is not critical at all. It could be set to a high
value without any impact. The power consumption of LTS survey, when Tlts_period is 1s, is less than 1nW. In
HRV_LOW mode, this period (Tlts_period_hrv_low) is set by reg_t_hrv_low_cfg.t_lts_hrv_low_period to a
different value, but as in operating the impact is negligible. We advise the user to set Tlts_period to 1s and
Tlts_period_hrv_low to 2s as follows:
reg_t_lts_period = 101
reg_t_hrv_low_cfg.t_lts_hrv_low_period = 101
Tlts_period is set by the registers reg_t_lts_period and reg_t_hrv_low_cfg.t_lts_hrv_low_period as follows:
Tlts_period
Tlts_period in HRV_LOW mode
Reg value
register :
reg_t_lts_period
register :
reg_t_hrv_low_cfg.t_lts_hrv_low_period
000
1ms
2ms
001
4ms
8ms
010
16ms
32ms
011
64ms
128ms
100
256ms
512ms
101
1s
2s
110
4s
8s
111
16s
32s
Table 5: Tlts_period and Tlts_period_hrv_low Related Registers Selection
Note: At start-up the EM8500 waits Tlts_period before to enable VSUP. Usually this is not critical as the start-up is
executed one time in the life of the product.
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TABLE OF CONTENTS
Storage elements STS/LTS supervising .......................................................................................................................1
ABSTRACT ..............................................................................................................................................................1
ABBREVIATIONS.....................................................................................................................................................1
1 Scope.....................................................................................................................................................................2
2 Supervising registers settings sequence ...............................................................................................................4
3 VLD reference .......................................................................................................................................................5
4 Operating mode settings .......................................................................................................................................6
4.1
Battery type ...................................................................................................................................................6
4.2
Battery protection ..........................................................................................................................................6
4.3
Force connection of LTS to STS in primary cell mode .................................................................................6
5 Absolute values settings ........................................................................................................................................7
5.1
Maximum battery voltage ..............................................................................................................................7
5.2
Maximum application voltage .......................................................................................................................7
5.3
Minimum battery voltage ...............................................................................................................................7
6 Short term storage capacitor setting .....................................................................................................................8
7 STS survey period .................................................................................................................................................9
7.1
Example of STS survey period calculation ...................................................................................................9
8 Hysteresis on v_bat_min settings ........................................................................................................................10
8.1
Level v_bat_min_hi with VDD_STS and VDD_LTS disconnected .............................................................10
8.2
Example of v_bat_min_hi_dis calculation ...................................................................................................10
8.3
Level v_bat_min_hi with VDD_STS and VDD_LTS connected ..................................................................11
9 Level v_apl_max_lo settings ...............................................................................................................................12
9.1
Level v_apl_max_lo toward v_bat_min_hi ..................................................................................................12
9.2
Level v_apl_max_lo toward v_apl_max_hi .................................................................................................13
9.3
Level v_apl_max_lo adjustment .................................................................................................................13
9.4
Level v_apl_max_lo with VDD_STS and VDD_LTS connected .................................................................14
10
Level v_bat_max_lo settings ...........................................................................................................................15
10.1
Level v_bat_max_lo with VDD_STS and VDD_LTS connected .............................................................15
11
LTS survey period ............................................................................................................................................16
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LIST OF TABLES
Table 1: List of Registers Related to Storage Elements Supervising .................................................................... 2
Table 2: Mapping of Registers in EEPROM .......................................................................................................... 3
Table 3: Vlvl Precision ........................................................................................................................................... 5
Table 4: Tsts_period Related Registers Selection ................................................................................................ 9
Table 5: Tlts_period and Tlts_period_hrv_low Related Registers Selection ....................................................... 16
LIST OF FIGURES
Figure 1: VDD_STS Measurement Toward v_bat_min_hi_dis ............................................................................ 10
Figure 2: Effect of v_apl_max_lo Level on VDD_LTS Charge Phase Delay ....................................................... 12
Figure 3: VDD_STS Measurement Toward v_apl_max_lo ................................................................................. 13
LIST OF EQUATIONS
Equation 1: VLD Reference Calculation ................................................................................................................ 5
Equation 2: reg_v_bat_max_hi Calculation ........................................................................................................... 7
Equation 3: reg_v_apl_max_hi Calculation ........................................................................................................... 7
Equation 4: reg_v_bat_min_lo Calculation ............................................................................................................ 7
Equation 5: Csts Calculaton; all Decoupling Capacitors Enabled Together ......................................................... 8
Equation 6: STS Survey Period Calculation .......................................................................................................... 9
Equation 7: Example of STS Survey Period Calculation ....................................................................................... 9
Equation 8: v_bat_min_hi_dis Calculation ........................................................................................................... 10
Equation 9: Register reg_v_bat_min_hi_dis Calculation ..................................................................................... 10
Equation 10: reg_v_bat_min_hi_con Toward reg_v_bat_min_lo Conditions ...................................................... 11
Equation 11: v_apl_max_lo Toward v_bat_min_hi_dis Condition ....................................................................... 12
Equation 12: Pin_max Caclulation ....................................................................................................................... 13
Equation 13: v_apl_max_lo Toward v_apl_max_hi Condition ............................................................................. 13
Equation 14: reg_v_apl_max_lo Toward reg_v_apl_max_hi Condition ............................................................. 14
Equation 15: v_bat_max_lo Conditions; v_apl_max_lo and v_apl_max_hi not Used ......................................... 15
Equation 16: reg_v_bat_max_lo Toward reg_v_bat_max_hi Condition ............................................................. 15
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