ACT8865 datasheet(24/32 Pages) QORVO

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ACT8865

Advanced PMU for Atmel SAMA5Dx Series & SAM9 Series Processors

Data Sheet Rev. H, September 2019 | Subject to change without notice

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FUNCTIONAL DESCRIPTION

2C Interface

The ACT8865 features an I

2C interface that allows

advanced programming capability to enhance overall

system performance. To ensure compatibility with a wide

range of system processors, the I

2C interface supports

clock speeds of up to 400kHz (“Fast-Mode” operation)

and

uses

standard

2C commands. I2C write-byte

commands are used to program the ACT8865, and I

read-byte commands are used to read the ACT8865’s

internal registers. The ACT8865 always operates as a

slave device, and is addressed using a 7-bit slave

address followed by an eighth bit, which indicates

whether the transaction is a read- operation or a write-

operation, [1011011x].

SDA is a bi-directional data line and SCL is a clock

input. The master device initiates a transaction by

issuing a START condition, defined by SDA transitioning

from high to low while SCL is high. Data is transferred in

8-bit packets, beginning with the MSB, and is clocked-

in on the rising edge of SCL. Each packet of data is

followed by an “Acknowledge” (ACK)

bit, used to

confirm that the data was transmitted successfully.

For more information regarding the I

2C 2-wire serial

interface, go to the NXP website: http://www.nxp.com.

Voltage Monitor and Interrupt

Programmable System Voltage Monitor

The ACT8865 features a programmable system- voltage

monitor, which monitors the voltage at VDDREF and

compares it to a programmable threshold voltage. The

programmable

voltage threshold is programmed by

SYSLEV[3:0], as shown in Table 3.

SYSLEV[ ] is set to 3.0V by default. There is a 200mV

rising hysteresis on SYSLEV[ ] threshold such that

VVDDREF needs to be 3.2V(typ) or higher in order to power

up the IC.

The nSYSSTAT[ ] bit reflects the output of an internal

voltage comparator that monitors VDDREF relative to

the SYSLEV[ ] voltage threshold, the value of nSYSTAT[

] = 1 when VVDDREF is lower than the SYSLEV[ ] voltage

threshold, and nSYSTAT[ ] =

0 when VVDDREF is higher than the SYSLEV[ ] voltage

threshold. Note that the SYSLEV[ ] voltage threshold is

defined for falling voltages, and that the comparator

produces about 200mV of hysteresis at VDDREF. As a

result, once VVDDREF falls below the SYSLEV threshold,

its voltage must increase by more than about 200mV to

clear that condition.

After the IC is powered up, the ACT8865 responds in one

of two ways when the voltage at VDDREF falls

below the SYSLEV[ ] voltage threshold:

1) If nSYSMODE[ ] = 1 (default case), when system v o l t

ag e l e v e l i n t e r r up t is u n ma s k e d (nSYSLEVMSK

[ ]=1) and VVDDREF falls below the programmable

threshold, the ACT8865 asserts nIRQ, providing a

software “under-voltage alarm”. The response to this

interrupt is controlled by the CPU, but will typically

initiate a controlled shutdown sequence either or alert

the user that the battery is low. In this case the

interrupt is cleared when VVDDREF rises up again above

the SYSLEV rising threshold and nSYSSTAT[ ] is read

via I

2C.

2) If nSYSMODE[ ] = 0, when VVDDREF falls below the

programmable threshold the ACT8865 shuts down,

immediately disabling all regulators. This option is

useful for implementing a programmable “under- voltage

lockout” function that forces the system off when the

battery

voltage falls

below

the

SYSLEV threshold

voltage. Since this option does not support a controlled

shutdown sequence, it is generally used as a "fail-safe"

to shut the system down when the battery voltage is

too low.

Table 3:

SYSLEV Falling Threshold

SYSLEV[3:0]

SYSLEV Falling Threshold

(Hysteresis = 200mV)

0000

2.3

0001

2.4

0010

2.5

0011

2.6

0100

2.7

0101

2.8

0110

2.9

0111

3.0

1000

3.1

1001

3.2

1010

3.3

1011

3.4

1100

3.5

1101

3.6

1110

3.7

1111

3.8

Thermal Shutdown

The ACT8865 integrates thermal shutdown protection

circuitry to prevent damage resulting from excessive

thermal stress, as may be encountered under fault

conditions. This circuitry disables all regulators if the

ACT8865 die temperature exceeds 160°C, and prevents

the

regulators

from

being

enabled

until

the

temperature drops by 20°C (typ).

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