Data Sheet

ADP8140

Rev. B | Page 17 of 23

left enabled, so that they can regulate the current if the open-

circuit or short-circuit LED condition is removed. Bringing EN

or VIN low and then high again restores all sinks to the

feedback loop.

VO_SNS can also be used to monitor the input voltage. When

connected to the input voltage through a resistor divider, the

ADP8140 shuts down and disables any power stages if the

supply input voltage rises too high. This shutdown can help to

protect the LEDs and power stage.

DIE TEMPERATURE PROTECTION

Significant voltage mismatch between LED strings can create

high power dissipation within the ADP8140. If this increase in

power dissipation causes the die temperature on the ADP8140

to rise above 135°C (typical), the IC automatically begins to

reduce the output current on all four sinks. If the die tempera-

ture continues to rise and exceeds 150°C (typical), the ADP8140

shuts down the power stage with COMP, FB_OUT, and

A

A

.

When the temperature drops below 130°C (typical), the

ADP8140 restarts the power stage. If the fault or high power

dissipation persists, the sequence repeats.

USING MULTIPLE ADP8140 ICS

Multiple ADP8140 ICs can be combined in parallel to control

the same supply. This combination is advantageous to control

more than four strings of LEDs or to drive higher currents. For

example, using two ADP8140 ICs, four LED strings can be

driven at 1 A each, or two strings can be driven at 2 A each.

When using multiple ADP8140 ICs in parallel to control one

power supply, all of the

A

A

and EN pins must be connected

together. If any

A

A

pin goes low, all ADP8140 ICs respond

to the event. Most applications will work best if the dimming

signals are also connected amongst the ADP8140 ICs, though it

is not required.

Figure 28. Multiple ADP8140 ICs Powered from One Supply (Low Gain Buffer Control Shown)

FAULT

ENABLE

ADP8140

VIN

VIN

COMP

REG

MODE

EN

FAULT

FB_OUT

MIN

VT

DIM

DIM

SINK1

SINK2

SINK3

SINK4

ISET

VO_SNS

EXPOSED PAD

ADP8140

VIN

VIN

COMP

REG

MODE

EN

FAULT

FB_OUT

MIN

VT

DIM

DIM

SINK1

SINK2

SINK3

SINK4

ISET

VO_SNS

EXPOSED PAD

VIN

ADP2384

BST

PGND

SW

PVIN

PVIN

GND

SW

SW

VREG

FB

COMP

PVIN

SW

PGND PGND PGND PGND PGND

RT

SS

SYNC

PGOOD

EN

PVIN