ISL9016

FN6832 Rev 1.00

Page 9 of 11

May 16, 2011

Block Diagram

Functional Description

ISL9016 contains two high performance LDO’s. High

performance is achieved through a circuit which delivers fast

transient response to varying load conditions. In a quiescent

condition, the ISL9016 adjusts its biasing to achieve the lowest

standby current consumption.

The device also integrates current limit protection, thermal

shutdown protection, reverse current protection and soft-start.

Thermal shutdown protects the device against overheating.

Soft-start limits the start-up input current surges. In some certain

application circuits, the output voltage may be externally held up,

meanwhile, the input voltage could be connected to ground, or

connected to some voltage lower than the output side, or be left

open circuit. ISL9016 features the reverse current protection; it

can limit the current flow from output to input. This protection will

Enable Control

The ISL9016 has two separate enable pins, EN1 and EN2, which

independently enable/disable each of the LDO outputs. When both

EN1 and EN2 are low, the whole device is in shutdown mode. In this

condition, all on-chip circuits are off, and the device draws minimum

current, typically less than 0.1mA. When one or both the EN pins go

high, the LDO1 and/or LDO2 will be enabled accordingly based on

the voltage signal applied on its related EN pin and start from the

soft-start. Likewise, when one or both EN pins go low, LDO1 and/or

LDO2 will be disabled based on the signal applied on its related EN

pin. A 100kΩ (or above) pull-up resistor should be connected

between ENx pin and the external control voltage (as shown in the

“Typical Application Diagram” on page 1).

LDO Protections

ISL9016 offers several protections which make it ideal for using

in battery-powered application circuits.

ISL9016 provides short-circuit protection by limiting the output

current to typical 265mA. When short circuit happens, the circuit

is limited at 265mA (typical). If the short circuit lasts long enough,

the die temperature increases, and the over-temperature

protection circuit will turn off the output.

When the die temperature reaches about +145°C, the thermal

protection starts working. Under the overheat condition, only the

LDO sourcing more than 50mA will be shut off. This does not

affect the operation of the other LDO. If both LDOs source more

than 50mA and an overheat condition occurs, both LDO outputs

will be disabled. Once the die temperature falls back to about

+110°C, the disabled LDO(s) are re-enabled and soft-start

automatically takes place.

In certain applications, the following input/output situations may

occur, with output voltage externally held up higher than the input

voltage:

1. Input is pulled to ground;

2. Input is left open circuit; and

3. Input is pulled to some intermediate voltage

ISL9016 provides the reverse current protection to limit the current

flow from output to input under these situations. When input is

pulled to ground and output is held to 5.5V, the typical reverse

current from output to input side is less than 8µA.

CONTROL

LOGIC

SHORT CIRCUIT

THERMAL PROTECTION

SOFT-START

UNDERVOLTAGE

LOCKOUT

BANDGAP

TEMP-SENSOR

REFERENCE

VOLTAGES

VREF1

VREF2

VREF3

VOUT1

EN1

+

VIN

VIN

EN1

EN2

VOUT2

VOUT1

GND

VREF1

REVERSE CURRENT

PROTECTION

LDO-2

LDO-1