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required for the OUT voltage to reach the10% of its own steady state value

time required for the current to flow in the enabled LSD

come zero in the previously enabled LSD.

Note 4: Guaranteed by design, not tested in production.

FUNCTIONAL DESCRIPTION

SMPS

The

N-channel

Power

MOSFET

is

source

grounded, thus it is possible to use any converter

configuration with the power switch connected to

ground. A SEPIC topology (Single Ended Primary

Inductor

Current)

is

shown

in

the

typical

application schematic.

INPUTS PINS

The IC’s inputs are TURN, STOP and TAIL. If all

inputs are disabled, SMPS and most of the

internal control and diagnostic circuitry are not

active. This is done in order to maintain the

stand-by quiescent current at very low values.

When only one of these inputs is put high (e.g

once the voltage on it has reached about 95% of

enabled. In order to allow the output to reach the

regulated

voltage

value

faster,

the

LSD

corresponding to the input enabled will conduct

Symbol

Parameter

Test Conditions

Min.

Typ.

Max.

Unit

Lamp Outage Detect

Threshold Voltage

150

200

250

mV

Threshold Voltage

1.2

1.3

1.6

V

External Voltage

Reference

3.6

3.8

4

V

Internal Band-gap Voltage

Reference (see schematic

diagram)

1.15

1.24

1.3

V

Device Enabled Lamp

Outage no fault High

Voltage

At

least one input enabled. No fault

condition.

V

Device Disabled Lamp

Outage no fault High

Voltage

V

Lamp Outage fault Low

Voltage

least one input enabled. Fault condition.

1.5

V

TURN, STOP and TAIL

Input Resistance

18.5

k

Ω

Thermal Shutdown

Threshold

(see Note 4)

150

°C

Thermal Shutdown

Hysteresis

(see Note 4)

10

°C

Time to Fault Indication

ON

60

µs

Time to Fault Indication

OFF

8ms

Voltage (see table 1)

V

Voltage (see table 1)

V

Voltage (see table 1)

V