ADP5360ACBZ-1-R7 datasheet(31/60 Pages) AD

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Data Sheet

ADP5360

Rev. 0 | Page 31 of 60

PGOOD Indication

The VOUT2OK bit, Address 0x2F, indicates whether the buck

boost regulator is working properly. Alogic high indicates that

the output voltage of the buck boost regulator is higher than 90%

(typical rising threshold) of the nominal output. When the

regulated output voltage falls lower than 87% (typical falling

threshold) of the nominal output, the VOUT2OK bit goes low.

The VOUT2OK bit status indication can be masked to the

PGOOD1 pin or PGOOD2 pin by setting the PGOODx_MASK

Soft Start

The ADP5360 buck boost regulator has an internal soft start

function that ramps up the output voltage in a controlled

manner upon startup, thereby limiting the inrush current. This

feature prevents possible input voltage drops when a battery or

a high impedance power source is connected to the input of the

device. The default typical soft start time is 1 ms for the regulator.

Other soft start times (8 ms, 64 ms, and 512 ms) can be

programmed for the ADP5360 by the I2C interface.

Active Discharge

The ADP5360 integrates an optional discharge switch from the

output node to ground. This switch turns on when the associated

regulator is disabled to help discharge the output capacitor

quickly. The typical value of the discharge switch is 255 Ω for the

regulator.

The active discharge feature can be enabled by setting the

DISCHG_BUCKBST bit, Address 0x2B, high for the buck boost

regulator.

Current-Limit Protection

The buck boost regulator in the ADP5360 includes peak current-

limit protection circuitry to limit the amount of positive current

flowing through the high-side MOSFET switch. The peak current

limit on the power switch limits the amount of current that can

flow from the input to the output. The programmable current-

limit threshold feature allows for the use of small size inductors

for low current applications.

Use the BUCKBST_ILIM[2:0] bits, Address 0x2B, via the I2C

interface to program the peak current-limit threshold on the

buck boost regulator. Three bit-programmable options provide

100 mAto 800 mA of peak current limit with a 100 mA step

peak current threshold range. Use the following equation to

find the regulator output current:

ILOAD2 = VIN2 × IPEAK2/2(VIN2 + VOUT2)

where:

ILOAD2 is the regulator output current.

VIN2 is the regulator input voltage.

IPEAK2 is the inductor peak current.

VOUT2 is the output voltage.

The peak current limit is different than the average current

limit on the battery input side. The average battery current is

a factor in different elements including, but not limited to, the

VIN2/VOUT2 relationship, the inductance, the switching

frequency, and the peak current-limit threshold. The average

battery current limit on each buck or buck boost regulator

can be roughly calculated and predicted by these elements.

However, the average current-limit accuracy is difficult to

guarantee due to variations in inductance and switching

frequency. Therefore, a careful calculation must be obtained

if the input source is coming from a weak battery, which

typically has high output impedance.

Stop Switching

The stop feature also can configure the buck boost regulator with

the STP pin input, which allows the user to temporarily stop

buck boost regulator switching.

When applyin a logic high level to the STP pin, the

corresponding regulator is forced to stop switching

immediately. When applying a logic low level to the STP pin,

the regulator resumes switching. Note that tens of ns delay time

exists from when the STP signal goes high to when switching fully

stops.

The stop signal control is valid only when the regulator is

enabled. Otherwise, the stop signal is ignored.

Set the STP_BUCKBST bit, Address 0x2B, low to disable the

buck boost regulator stop switching feature.

SUPERVISORY

Reset Output

TheADP5360 provides microprocessor supply voltage supervision

by controlling the reset input of the microprocessor. When the

monitored voltage falls lower than the associated threshold, the

RESET pin asserts correspondingly. Asserting the RESET pin

quickly ensures that the entire system is reset immediately

before any part of the system voltage falls lower than the

recommended operating voltage. The default monitor voltage

is the buck output voltage (VOUT1) and can be selected as

VOUT2 by the I2C interface. The RESET pin monitors both

VOUT1 of the buck and VOUT2 of the buck boost when setting

the VOUT1_RST bit and VOUT2_RST bit of Address 0x2D

both high.

ADP5360ACBZ-1-R7 Datasheet(PDF) 31 Page - Analog Devices

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