ZXLD1321

Issue 1 - January 2008

5

www.zetex.com

© Zetex Semiconductors plc 2008

DC-DC converter supply parameters

NOTES:

(a) Production testing of the device is performed at 25

°C. Functional operation of the device and parameters specified from -40°C to

+125

°C are guaranteed by design, characterisation and process control.

(b) Between 1.2V and 2.2V the device will run in the Low Voltage Startup Mode (for details refer to section "Low Voltage Operation")

DC-DC converter input parameters

Symbol

Parameter

Conditions

Min

Typ

Max

Units

Supply voltage

Normal operation

2.0

12

V

Supply voltage for start-up(b)

Start-up mode

1.2

2.4

V

Under-voltage detection threshold

Normal operation to start-up mode

VIN falling

1.8

V

Under-voltage detection threshold

Start-up mode to normal operation

VIN rising

2.2

V

Iq

Quiescent current

Measured into VIN

ADJ pin floating.

(Excluding switch

base current).

1.5

mA

Standby current

Measured into VIN.

ADJ pin grounded

12

20

µA

Internal reference voltage

ADJ pin floating

2.0V<VIN<18V

480

500

520

mV

Internal reference temperature

coefficient.

50

ppm

/K

Symbol

Parameter

Conditions

Min

Typ

Max

Units

Peak switch current sense

voltage

Measured on ISENSE

pin CFB pin at 0V

45

55

65

mV

(SU)

Peak switch current sense

voltage in start-up mode

Measured on ISENSE

pin.

Start-up mode

VIN=1.2V

10.5

mV

Sense input current

Measured into

ISENSE with pin at

0V. CFB pin at 0V

-15

-7

-1

µA

Control loop compensation

capacitor

10

nF

External dc control voltage

applied to ADJ pin to adjust

output current

DC brightness

control mode

50

500

mV

Switching threshold of ADJ

pin

Standby state to

normal operation

26

28

30

mV

Temperature coefficient of

VADJ(th)

+0.3

%/K

Internal resistor between

VREF and ADJ

VADJ<500mV

100

k

Ω

VADJ(clmp) Clamp voltage on ADJ pin

100µA injected into

ADJ pin

575

mV