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KTZ8866

January 2022 - Revision 04b

Page 23 of 37

Company Confidential

Fast Discharge

KTZ8866 has internal switch resistance for discharging OUTP and OUTN when device is shutdown. The

OUTP discharge function is enabled with register 0x09 bit [4] and the OUTN discharge is enabled with register

0x09 bit [3].

OUTP Short Circuit Protection

If output current of OUTP is greater than 240mA (typical), the OUTP_SHORT flag will be set in register 0x0F. A

I2C readback is required to clear the flag. The outcome of an OUTP_SHORT detection depends on the setting

of register 0x0A bits [7:6], including report-only flag, shutdown OUTP/OUTN, and shutdown OUTP/OUTN and

backlight. KTZ8866 provides four level short circuit detection

filter: 100μs, 500μs, 1ms, and 2ms by register 0x0B

bits [3:2] to avoid false trigger problems.

OUTN Short Circuit Protection

OUTN_SHORT flag will be set in register 0x0F if OUTN is found shorted to ground. An I2C readback of register

0x0F is required to clear the flag. The outcome of an OUTN_SHORT detection depends on the setting of register

0x0A bits [7:6], including report-only flag, shutdown OUTP/OUTN, and shutdown OUTP/OUTN and backlight.

KTZ8866

provides four level short circuit detection filter options: 100μs, 500μs, 1ms, and 2ms by register 0x0B

bits [1:0] to avoid false trigger problems.

Soft Reset

All the I2

C registers can be reset to their default settings by writing ‘1’ to the SOFTWARE_RESET bit in Register

0x08,

this bit will be reset to ‘0’ automatically after the software reset.

UVLO

Under voltage lock-out (UVLO) featured is included to monitor the input voltage VIN. Once VIN drops below

UVLO falling threshold, the current sinks are disabled and the boost converters stop switching. After VIN

increases above UVLO rising threshold, the boost converters and the current sinks will resume to their previous

setting.

Thermal Shutdown

The KTZ8866 has Thermal Shutdown Protection which will turn off the backlight boost, all current sinks, LCD

bias boost, inverting charge pump, and the LDO when the die temperature reaches or exceeds 150°C (typ). The

I2C access is still available during Thermal Shutdown event, but TSD flag will be set in register 0x0F, this bit is

real time reflection of TSD. When TSD is gone, the bit will be reset back to 0 automatically.

Device Functional Modes

Shutdown: The KTZ8866 is in shutdown when the HWEN pin is low. I2C writes are not recognized in shutdown.

Standby: After the HWEN pin is set high the KTZ8866 goes into standby mode. In standby mode, I2C writes are

allowed but references, bias currents, the oscillator, LCD Bias, and backlight are all disabled to keep the

quiescent supply current low.

Normal mode: Each of the main blocks of the KTZ8866 are independently controlled. For details on how to

control each mode, see Tables 1 and 4.