ADP5360ACBZ-2-R7 datasheet(29/60 Pages) AD

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Data Sheet

ADP5360

Rev. 0 | Page 29 of 60

Program Output Voltages

Adjustable output voltage settings are available on the ADP5360

by connecting a resistor through the VID1 pin to the AGND1

and AGND2 pins. The VID detection circuitry works in the

start-up period, and the voltage ID code is sampled and held

into the internal register and does not change until the next

power recycle.

Table 16 lists the output voltage options for the VID1 pin

configurations. Additional output voltage options from 0.6 V to

3.75 V with a 50 mV step are available on the ADP5360, and to

program these options set the VOUT_BUCKBST[5:0] bits,

Address 0x2C via the I2C interface. The ADP5360 also has a fixed

output voltage that is programmed via the factory fuse. In this

case, connect the VID1 pin to the VIN1 pin.

Table 16. VOUT1 Default Set Using the VID1 Pin

VID1 Resistor, RVID1 Value (kΩ)

VOUT1 Value (V)

100

3.3

3.0

2.8

2.5

1.8

1.5

1.2

1.0

For the output voltage settings, the feedback resistor divider is

built into the ADP5360, and the feedback pin (FB1) must be

tied directly to the output. An ultra low power voltage reference

and an integrated high impedance feedback divider network

contribute to the low quiescent current. Floating the VID1 pin

activates the register default value when powering up.

Enable and Disable

The ADP5360 includes a hardware enable pin (EN1). A logic

high on the EN1 pin starts the buck regulator. Due to the low

quiescent current design, it is typical for the regulator to start

switching after a delay of a few milliseconds from when the

EN1 pin is pulled high. Do not pull the EN1 pin high to the

ISOB pin because that can cause unexpected leakage current. It

is recommended to pull the EN1 pin high to the VSYS pin with

a resistor.

The EN_BUCK bit, Address 0x29, can control the buck enable

and disable, which is logically ANDed with the EN1 pin. For

example, set the EN_BUCK bit high, and use the EN1 pin

control buck to enable or to disable. Alternatively, pull the EN1

pin high and set the EN_BUCK bit via the I2C interface.

PGOOD Indication

The VOUT1OK bit, Address 0x2F, indicates whether the buck

regulator is working appropriately. Alogic high indicates that the

output voltage of the buck 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 VOUT1OK bit goes low.

The status indication of the VOUT1OK bit can be masked to

the hardware pin output of the PGOOD1 pin or PGOOD2 pin

by setting Register PGOODx_MASK with the I2C interface.

Soft Start

The ADP5360 buck regulator has an internal soft start function

that ramps up the output voltage in a controlled manner during

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.

100% Duty Cycle Operation

When the input voltage approaches the output voltage, the

ADP5360 stops switching and enters 100% duty cycle operation.

The buck connects the output via the inductor and the internal

high-side power switch to the input. When the input voltage is

charged again, and the required duty cycle falls to 95% typical, and

the buck immediately restarts switching and regulation without

allowing overshoot on the output voltage.

Active Discharge

The ADP5360 integrates an optional discharge switch from

the switching 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_BUCK bit, Address 0x29, high for the buck regulator.

Current-Limit Protection

The buck regulator in the ADP5360 has protection circuitry

that limits the direction and the amount of current to a certain

level that flows through the high-side MOSFET and the low-side

MOSFET in cycle by cycle mode. The positive current limit on

the high-side MOSFET limits the amount of current that can

flow from the input to the output. The negative current limit on

the low-side MOSFET prevents the inductor current from

reversing direction and flowing out of the load.

ADP5360ACBZ-2-R7 Datasheet(PDF) 29 Page - Analog Devices

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