ZXLD1374

ZXLD1374

Document number: DS35032 Rev. 1 - 2

Page 28 of 35

www.diodes.com

October 2010

© Diodes Incorporated

A Product Line of

Diodes Incorporated

VR EF

0V

0A

Normal

Operations

SEVERITY

4.5V

3.6V

2.7V

1.8V

0.9V

VAUX

UVLO

-VI N UVLO

-STALL

-OU T of REG

ZXLD1374

Switch OV

Over

Temperature

Over

Current

01

2

3

4

5

Fig 48. Status levels

In the event of more than one fault/warning condition occurring, the higher severity condition will take precedence. E.g.

‘Excessive coil current’ and ‘Out of regulation’ occurring together will produce an output of 0.9V on the STATUS pin.

Diagnostic signals should be ignored during the device start – up for 100

μs. The device start up sequence will be initiated

both during the first power on of the device or after the PWM signal is kept low for more than 15ms, initiating the standby

state of the device.

In particular, during the first 100

μs the diagnostic is signaling an over-current then an out-of-regulation status. These two

events are due to the charging of the inductor and are not true fault conditions.

Over-

current

Out of

regulation

V

REF

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0

20

40

60

80

100

120

140

160

180

200

time (µs)

Over-

current

Out of

regulation

V

REF

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0

20

40

60

80

100

120

140

160

180

200

time (µs)

Figure 49. Diagnostic during Start-Up