8.9

IC Supply

8.9.1

Primary side LDO

A 3.3 V regulator generates the voltage for internal circuitry and digital I/Os. The regulator requires an 100 nF

capacitor connected from P3V3 to PPGND.

8.9.2

Secondary side Charge pump & LDO

An internal LDO provides the supply for the IC analog & digital circuits. The SV3V internal LDO can be used to

supply external circuits up to 2 mA.

A voltage doubler charge pump provides the driving voltage for the synchronous rectifier. The voltage which can

be obtained is approximately 2 * (SVCC – Vf), where Vf is the external diode forward voltage.

The charge pump is turned on when the regulation voltage is below a threshold set by the configuration

parameters.

A second LDO provides the 1.2 V supply for the IC logic.

8.9.2.1

LDO decoupling

The 3V3 LDOs require a 1 uF ceramic capacitor to ground to decouple the supply voltage and guarantee stability.

The V1V2 LDO requires a 4.7 uF ceramic capacitor to ground.

The capacitors should be located as near as possible to the device.

8.10

Power Good

The GPIO1 is configured as a power good pin. The purpose of this pin is to disable a DC/DC converter controlling

the second port during the system startup until the AC/DC converter has terminated its soft-start and reached a

stable operation.

8.11

Secondary side controller

The secondary side includes a digital controller which is in charge of both the power conversion and the

communication with the load through USB-PD.

Figure 10. Secondary side block diagram

CORTEX M0+

64kB program

memory + 8kB

boot

8kB SRAM

GPIO

SMED 0 & 1

SMED 2

Connection

box

OSCILLATOR

PLL

Oring FET

Driver & Charge

pump (sys ctrl)

TYPE-C phy

SCHEDULER

Temperature

sense

LDO & Charge

pump

66kHz clk

Power & clock

manager (sys

ctrl)

Duty cycle

estimator

Watchdog

VCCPART

WakeRef

Wakeup

VCLAMP

VCLAMP

CS_AMP

GPIO0

SRVDS

VOPART

Int Temp

VCCPART

GPIO1

12 bit

ADC

SMED Event bus

SWD

I2C

UART

SRGD

CSM

CSP

CC2

CC1

VDRV

PUMP

SV3V

V1V2

SVCC

ISO TX

VOSNS

Bleeder ctrl (sys

ctrl)

VOPART

VCCPART

1V

VZCD

IZCD

GPIO1

GPIO0

VDRV

Clamp

SR1V

SVCC

SPGND

ST-ONEMP

IC Supply

DS13989 - Rev 2

page 26/39