Using the HT45FH5N in Type-C Quick Charge Power Bank ...Using the HT45FH5N in Type-C Quick Charge...

AN0456E V1.00 1 / 15 April 25, 2017

Using the HT45FH5N in Type-C Quick Charge Power Bank Applications


D/N: AN0456E

Instruction Quick charge technology now exists as a mature technology resulting in huge improvements

to mobile phone charging speeds. The Type-C interface provides a bidirectional power supply

function, which allows power bank applications to charge or discharge via a single port.

Additionally, quick charge technology has an improved effect on the charging/discharging

current. Holtek’s special purpose power bank management ICs provide solutions for all of

these functions. This text will initially introduce the power bank charge and discharge

principles after which it will explain the control flowchart for each process, allowing users to

have a deeper understanding of Holtek’s power bank management ICs.

Functional Description

Power Bank Charge Functional Description

USB interfaces all require a 5V operating voltage However Lithium batteries, which are

the usual type of battery used in power banks, have a voltage of 3.7V, a buck converter is

required to implement the voltage reduction when using external USB power sources to

charge the power bank battery. This voltage conversion buck converter management is

implemented using the device’s integrated PWM function. The integrated OUVP and

OCP functions within the device also provide further over/under voltage protection and

over current protection during the charging process. There are three charging control

modes, trickle current charge mode, constant current charge mode and constant voltage

charge mode. The required charging voltages and currents for these modes differ

according to different user designs. These charging modes are described below.

Trickle Current Charging Mode: used for completely discharged batteries which have a

voltage of less than 3V. In this mode the battery will be pre-charged using a typical

0.1C(Note) constant trickle current during this first stage of charging.

Constant Current Charging Mode: when the battery voltage is greater than 3V, the charging

current will then switch to a typical 1C(Note) constant current during this second charging

stage.

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Constant Voltage Charging Mode: once the battery voltage has exceeded 4.1V, it will be

charged using a constant voltage during this third stage. The charge current decreases

gradually as the constant voltage charge time increases. Typically, the constant voltage

charge stage is completed when the charge current reduces to a value of less than 0.1C.

Note: taking a 1000mAh Li-battery as an example, a value of 0.1C means charging the battery

using a 100mA current and 1C means charging the battery using a 1000mA current.

Power Bank Discharge Functional Description

The power bank system includes a detection circuit to identify whether any external

devices such as a mobile phone is inserted or not. As the power bank USB interface

output voltage is 5V but as the Li-battery voltage is only 3.7V, a voltage boost conversion

process is required to implement the discharge process. This voltage boost conversion

management is implemented using the device’s integrated PWM function. The integrated

OCP function also provides over current protection for this process. There are two

discharge control modes, constant voltage discharge mode and constant current

discharge mode, which will be described below.

Constant Voltage Discharge Mode: the internal PWM function is used to control the

voltage boost circuit to ensure a constant 5V output. In this stage, current detection is

implemented to monitor the present discharge status. If the output current is too small, the

system will conclude that the mobile phone or other connected device has been removed

and will consequently switch off the power bank. If the output current is too large, the

system will switch to the constant current discharge mode to avoid any current overload

conditions.

Constant Current Discharge Mode: when the output current is too large, the system will

maintain a constant current output to avoid overload conditions. In this stage, current

monitoring is continued. Under normal conditions, the mobile phone or other connected

device will conclude that the current is fixed and will not further increase the loading.

However, if under abnormal conditions the mobile phone or other connected device

continues to increase the load resulting in a large current output, this will be detected by

the power bank system resulting in the corresponding protection function being

implemented.

Power Bank QC and MTK Discharge Functional Description

During discharging, the power bank will implement a quick charge recognition operation

on the connected device. If the connected device contains a quick charge function, the

power bank will supply a corresponding voltage output of 5V~12V according to the

device’s requirement.

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Hardware Block Diagram

HT45FH5N Type-C Quick Charge Power Bank Hardware Block Diagram

1. As the Type-C IN/OUT interface and the USB IN/OUT interface both operate at 5V

but as the power bank battery voltage is 3.7V, a voltage conversion operation is

required. Management of this voltage conversion is implemented using an MCU

together with an output complementary PWM circuit to control the PMOS+NMOS

power transistors and inductor components to form the charging buck and

discharging voltage boost conversion circuit.

2. Regarding the internal OUVP circuit, during normal operations the OUVP pin input

voltage is sampled by the ADC and controlled by the charge buck control management

system. When an over/under voltage situation occurs, the MCU will respond

immediately to disable the PWM outputs to protect the battery.

3. Regarding the internal OCP circuit, during normal operations the sensor current is

input via the corresponding OCP pin, amplified by an OPA and then sampled by the

ADC. When an over current situation occurs, the MCU will respond immediately to

disable the PWM output to protect the battery.

4. Battery Voltage Detection: during charging, the charge mode will be determined to be

either a trickle current, constant current or constant voltage mode, according to the

present battery voltage condition. During discharging, the remaining battery capacity

will be determined and discharging will cease if the power level is too low.

5. LEDs and Buttons: use a button as the power bank on/off control and use four LEDs

to display the present battery capacity level, 25, 50, 75 or 100%.

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Hardware Circuit

HT45FH5N Type-C Quick Charge Power Bank Circuit

MCU Operating Conditions Sleep status: VDD =3.0V~4.2V, Work status: VDD=5V

Oscillator: 8MHz

Low Voltage Reset: 2.55V

Watchdog Timer timeout: 500ms

Software Description Program Memory: 4K×16 -- uses 3201×16, usage: 78%

Data Memory: 256×8 -- uses 122×8, usage: 47%

ADC: used for voltage and current sampling during charging/discharging

PWM: used to control boost and buck circuits during charging/discharging

PWM ADJ: PWM duty auto adjustment by the hardware during discharging

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Timer: use the STM as a Timer Counter to generate an interrupt every 4ms and set a

variable to increment by one each time an interrupt is generated.

4ms: update the LED power capacity display

8ms: set the D_stateCheck_f flag for QC discharge recognition

8ms: set the Check_Mtk_f flag for MTK discharge recognition

8ms: set the TYPEC_Check_f flag for Type-C recognition

8ms: set the Check_Vin_f flag for input voltage monitoring

8ms: set the Det_Out_f flag for load detection

8ms: set the Det_Cap_f flag for battery capacity detection

1s: set the Usb2_in_Time flag for QC discharge recognition

500ms: Type-C detection count flag

Software Main Flowchart Description

HT45FH5N Type-C Quick Charge Power Bank Software Main Flowchart

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1. Initialisation: RAM clear, pin function initialisation, WDT setup, OUVP calibration.

2. Sleep flag judgement: when the Sleep_f flag is set, operations such as stopping the

PWM function, turning off the charge/discharge port, configuring the pin function and

clearing the Data Memory will be implemented before entering the sleep mode. If the

Sleep_f flag is “0”, go to the next process.

3. Key scan: to determine whether the key is pressed continuously. Setup a parameter

Key_OFF_Cnt and start counting. This value will then be compared with the

parameter value preset by the software. If these two values are equal, I/O pin PB6 will

be configured as an output to control the flashlight on/off function.

4. Timer count: determine if the time interrupt 8ms flag is set. If it is high, setup the

corresponding charge/discharge flag. If it is low, skip this step.

5. LED power capacity display: use LEDs to display the battery capacity. Update and

indicate the present battery capacity during charging or the remaining capacity during

discharging.

6. Work status judgement: determine the software parameter Work_Status value. Enter

the charge mode if it is “0” or enter the discharge mode if it is “1”.

7. Battery capacity detection: time interrupt will set the Det_Cap_f flag to “1” every 8ms.

If this flag is high, the battery capacity detection process will be activated, the

charge/discharge power comparison will then be executed. More details are described

below.

Charge power comparison: in the charge mode, use the ADC (OVP00) to measure

the present voltage which is then compared with the parameter values preset by

the software. When the measured value matches a preset value range, in the next

charge power update process the corresponding power level will be displayed

using LEDs. The software power comparison is divided into three levels, as shown

below.

Power: 3.00~3.82(V) - Chavol_table[0] defined in RXX.C



Discharge power comparison: in the discharge mode, use the ADC (OVP00) to

measure the present voltage which is then compared with the parameter values

preset by the software. When the measured value matches a preset value range, in

the next discharge power update process the corresponding power level will be

displayed using LEDs. The software power comparison is divided into three levels,

as shown below.




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8. Load detection: a time interrupt will set the Det_Out_f flag high every 8ms, the load

detection process will be activated when this flag is high. Use the ADC(OTI-1, INI) to

measure current which is then compared with the parameter value preset by the

software to determine if the charge/discharge port is in an unloaded status.

9. Type-C recognition: a time interrupt will set the TYPEC_Check_f flag high every 8ms.

The Type-C recognition will be processed when this flag is high. If Type-C is in a

charge status, the charge flag DPF_IN_f will be set to “1” while the discharge flag

UPF_IN_f will be set if Type-C is in a discharge status.

Software Charge Subroutine Description

HT45FH5N Type-C Quick Charge Power Bank Charge Subroutine Flowchart

1. OPA calibration: the OCP OPA should be properly calibrated when entering the

charge mode at the first time. After the OPA calibration is complete, the OFF_Set_f

flag will be set, which indicates such an operation is not required during later

processes unless the power bank enters the sleep mode and clears this flag.

2. Input voltage determination: determine if the Micro-B and Type-C have a voltage

input by checking MIRC_IN_PIN(PA4) and TYPE_C_PIN(PA3). If both pins are high,

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indicating that there is no input voltage access, the Sleep flag will be set. If any of

them are low, the program flow will continue to determine whether it is a Micro-B

voltage input or a Type-C voltage input. If the MIRC_IN_PIN(PA4) is low, the PA6 pin

output will be controlled to turn on the MOS to implement a Micro-B charge input. If it

is high, the PC5 output will be controlled to turn on the MOS to implement a Type-C

charge input.

3. Input voltage detection: use the ADC (OVP01) to read the input voltage which is then

compared with the parameter value preset by the software. When the ADC sampled

value is less than the preset value, the charge process will cease. The preset

parameter value can be set by V_IN_4V3 defined in the head.h file.

4. Charge management: execute the complete charge modes, including trickle current

charging, constant current charging and constant voltage charging modes, which will

be described later.

HT45FH5N Type-C Quick Charge Power Bank Charge Subroutine Flowchart

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1. Battery insertion determination: setup a Bat_Ok_f flag using the software and

executea battery insertion detection process when this flag is “0”. Determine whether

it is a Micro-B input or a Type-C input and turn on the corresponding charge input

port. During the battery insertion detection, use the ADC(INI) to read the input current

which is then compared with the parameter value preset by the software. When the

ADC sampled value is greater than the preset parameter value, indicating that the

battery is properly inserted, the Bat_OK_f flag will then be set. The parameter value

can be set by CUR_200mA defined in the head.h file.

2. ADC read battery voltage: use ADC(OVP00) to read the battery voltage which is then

compared with the parameter value preset by the software to determine which

charge mode is required at the present time. The charge modes include trickle

current charge, constant current charge and constant voltage charge modes, which

are described below:

Trickle current charge: when the ADC sampled voltage value is less than the preset

parameter value of 3V, the trickle current charge flag will be set and the battery will

be charged using the constant current charge mode procedure with a trickle charge

current of 200mA. The voltage value of 3V can be set by BATV_3V while the current

value 200mA can be set by CUR_200mA. These two parameters are defined in the

head.h file.

Constant current charge: when the ADC sampled voltage value matches the preset

voltage value range of 3V~4V, the power bank will enter the constant current charge

mode, the procedures for which are described in detail in the following flowchart. The

voltage parameter value of 4V can be set by BATV_4V defined in the head.h file.

Constant voltage charge: when the ADC sampled value is greater than the preset

parameter value 4.2V, the constant voltage flag will be set. The corresponding

execution procedures are described in detail in the flowcharts shown later. The

voltage parameter value 4.2V can be set by BATV_4V25 defined in the head.h file.

3. Battery full flag judgement: when the battery is fully charged, the battery full flag

Bt_Full_f will be set high and the charge process will then cease.

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Software Constant Current Charge Subroutine Description

HT45FH5N Type-C Quick Charge Power Bank Constant Current Charge Subroutine Flowchart

1. Start charge flag determination: setup a Start_Cha_f flag, this flag will be set high in

the initialisation procedure and a QC charge recognition will process to enable the

PWM function.

2. Trickle current charge flag determination: set the charge current as 0.2A when the

flag Trickle_Charge_f is high and start the trickle current charge. The parameter

value of 0.2A can be set by CUR_200mA defined in the head.h file.

3. Supply limit voltage: during charging, the maximum supply limit should be set as 4.4V,

which can be set by V_IN_4V4 defined in the head.h.

4. Supply limit voltage determination: use the ADC(OVP01) to read the input voltage,

which is then compared with the supply limit voltage value preset by the software.

When the ADC sampled value is less than the preset supply limit value, the

corresponding flag Limi_PWM_f will be set high and vice versa. The PWM will be set

to reduce the duty instead of increasing duty.

5. ADC read Input current: use ADC(INI) to read the input current which is then

compared with the charge current value preset by the software. When the ADC

sampled value is greater than the preset charge current value, the PWM will be set to

reduce the duty, while the duty will be increased if the sampled value is less.

6. Start charge flag determination: setup a Start_Cha_f flag, this flag will be set high

during the initialisation process to enable the PWM function.

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Software Constant Voltage Charge Subroutine Description

HT45FH5N Type-C Quick Charge Power Bank Constant Voltage Charge Subroutine Flowchart

1. Supply limit flag determination: determine the supply limit flag Limi_PWM_f status.

When this flag is high, the PWM will be set to reduce the duty.

2. ADC read battery voltage: use ADC(OVP00) to read the battery voltage which is then

compared with the preset parameter value 4.2V. When the ADC sampled value is

less than the preset parameter value, the PWM will be set to reduce the duty, while

the duty will increase if the sampled value is greater than the preset value.

3. ADC read input current: use ADC(INI) to read the input current which is then

compared with the parameter value 0.2A preset by the software. If the ADC sampled

value is greater than the preset parameter value, clear the constant voltage charge

flag CV_Mod_f, if the ADC sampled value is less, set the battery full flag Bt_Full_f.

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Software Discharge Subroutine Description

HT45FH5N Type-C Quick Charge Power Bank Discharge Subroutine Flowchart

1. Micro-B input voltage determination: in the discharge mode, if a Micro-B input voltage

is detected, it will switch to the charge mode.

2. Type-C charge/discharge flag determination: in the discharge mode, if the Type-C

charge flag DPF_IN_f is high and the Type-C discharge flag UPF_IN_f is low, it will

switch to the charge mode.

3. Output current flag determination: when the output current is less than the preset

parameter value, the CC_OUT_f flag will be low for Type-A while the CC_OUT_f1

flag will low for Type-C, which will activate the voltage boost output process. If the

flag is high, the PWM duty will be reduced.

4. Voltage boost output: except for the 5V output, the discharge mode also contains

high pass QC discharge recognition and MTK discharge recognition. Details are

described below:

High pass QC: the output voltage is adjusted according to the recognition with an

output voltage range of 5V~12V.

MTK: the output voltage can be 5V, 7V, 9V and 12V according to the recognition.

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5. Type-C discharge flag determination: determine the discharge flag UPF_IN_f. The

Type-C discharge output will be turned off if this flag is low. When the flag is high, the

Type-C will be turned on only if the QC flag QC_HiVol_f and MTK flag MTK_MODE_f

are both low.

6. Type-A discharge flag determination: determine the Det_Short_f flag. If this flag is

low, turn on the Type-A output; If it is high, turn off the Type-A output and set the

Sleep_f flag.

7. Output current detection: in the initial processes, the maximum output current is set

as 3A. The maximum output current parameter value should be set as 2.1A for 9V

output voltage and 1.6A for 12V output voltage. After this, use the ADC(OTI-1, INI) to

read the output current which is then compared with the preset maximum output

current parameter value. When the ADC sampled value is greater than the preset

value, the CC_OUT_f flag will be set for Type-A and the CC_OUT_f1 will be set for

Type-C. When the ADC sampled value is greater than the result of the maximum

preset current value added to 0.2A, the Det_Short_f flag will be set. Additionally, use

ADC(OVP01) to measure the output voltage which is then compared with the

parameter value 3.5V preset by the software. If the ADC sampled value is less, which

indicates a short circuit condition, the Type-A and Type-C discharge outputs will both

be turned off while the Det_Short_f flag will be set. The preset current parameter

values of 3A, 2.1A and 1.6A can be setup by the OUTPUT_3A, OUTPUT_2A1 and

OUTPUT_1A6 while the 3.5V voltage parameter value can be set by the

V_OUT_3V5. These parameters are defined in the head.h file.

8. QC recognition: determine if the connected device contains the high pass quick

charge function, whose result will be recorded. The corresponding voltage will be

output to discharge on the connected device during the next voltage boost process.

9. MTK recognition: determine if the connected device has an MTK quick charge

function, whose result will be recorded. The corresponding voltage will be output to

discharge on the connected device during the next voltage boost process.

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Operating Description

Demo Board Operating Description

1. BAT+, BAT-: the positive and negative ends of the Li-battery are connected to BAT+

and BAT- respectively.

2. LEDs: used for the display which indicates the remaining capacity and

charge/discharge power display.

3. Button: press to display the power level.

4. Flashlight: press continuously to turn on the flashlight.

5. Micro-B Input: external power input to charge the power bank

6. Type-C Input/Output: external power input to charge the power bank or supply power

for external mobile phones.

7. Type-A Output: to supply power for external devices

Conclusion

This application note has introduced how to use the HT45FH5N for quick charge power

bank applications as well as describing power bank charge/discharge principles and

related application software control flows. With regard to the power bank

charge/discharge management, a synchronous rectification function has been

implemented for better efficiency and lower standby current. The integrated OVP, UVP

and OCP functions reduce the requirements for large numbers of external components

resulting in reduced PCB area. All voltage and current thresholds for the charge and

discharge modes have been parameterized, making it more convenient for threshold

adjustment during product development.

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Version and Modification Information

Date Author Issue

2017.4.12 李振榮 First Version

Reference Files

Reference file: HT45FH5N Datasheet

For more information, refer to the Holtek official website http://www.holtek.com/en/

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Using the HT45FH5N in Type-C Quick Charge Power Bank ...Using the HT45FH5N in Type-C Quick Charge...

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