HUSB238

Data Sheet

©2023 Hynetek Semiconductor Co., Ltd. All rights reserved.

Page 10 of 17

ISET PIN

A fixed 100μA current source is applied on ISET pin. Connect a resister between ISET and GND to indicate the

ISET_CURRENT value as shown in Table 7.

Table 7. ISET_CURRENT Setting

RISET (kΩ)

ISET_CURERNT (A)

0

1.25

4.53

1.5

7.5

1.75

10.5

2

13.7

2.25

16.5

2.5

19.6

2.75

22.6

3

Open

3.25

The RDO current of the HUSB238 is determined by the lower value between ISET_CURRENT and

SNK_PDO2_CURRENT. SNK_PDO2_CURRENT is programmable by internal fuse options and the default value is

3.25A. The requested current value can be changed dynamically with the resistance value change.

RDO DETERMINATION

There are two ways to determine the RDO that the HUSB238 requests from the PD source. Set by the VSET and

ISET pins or set by the internal factory programmed fuse options. The HUSB238 compares the two values and uses

the lower value as its RDO.

For example, if the VSET and ISET is configured as 9V / 3A. The internal factory fuse option is 12V / 2A. Then the

RDO that HUSB238 requests from the PD source is 9V / 2A.

After the RDO is determined, the HUSB238 loops through the PD source PDOs from highest voltage first to find the

first PDO that satisfies the following conditions:

1.

SOURCE_PDO_VOLTAGE ≤ RDO_VOLTAGE

2.

SOURCE_PDO_CURRENT ≥ RDO_CURRENT

If both the conditions above are satisfied, then HUSB238 sends a request for this source PDO with operating current

set to the RDO current value.

If either one of the condition is not satisfied, the HUSB238 continues to compare with the second highest voltage

source PDO or requests 5V source PDO directly, depending on the internal fuse options. The default fuse option is to

continue to compare with the second highest voltage source PDO. Please contact local Hynetek sales for a device

with options other than the default option.

OPERATION WITH I2C INTERFACE

The HUSB238 is I2C communication capable with system MCU or processor through SDA and SCL pins. The

HUSB238 works as I2C slave role and the I2C address is 0x08.

After POR (Power On Reset), the HUSB238 receives the source capability information from the PD source adapter

and the HUSB238 saves the source capability information in registers. The system MCU can visit the HUSB238

registers through the I2C bus and select a proper PDO to request from external PD source.

The I2C has the highest priority. If using I2C to select a source PDO, it over writes the internal RDO which is created

by VSET, ISET pins and internal factory fuse option, and the HUSB238 requests the I2C selected source PDO once

the I2C commands are written.

LEGACY CHARGER DETECTION

After the power on reset, if the HUSB238 does not establish PD contract with source adapter, the HUSB238 will waits

for 1.5 seconds and then switches to Apple Divider 3 and BC1.2 detections sequentially. For BC1.2 detection, the

HUSB238 detects SDP (Standard Data Port), CDP (Charging Data Port) and DCP (Dedicated Charging Port)

sequentially.