ISL9016
9
FN6832.1
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
automatically initiate when V
OUT
is detected to be higher than V
IN
.
When V
IN
is pulled to ground and V
OUT
is held at 5.5V, the current
flow from V
OUT
to V
IN
is typically less than 8µA.
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
