Diodes ZXLD1321 - Manual (Page 5)

ZXLD1321
Issue 1 - January 2008 5 www.zetex.com
© Zetex Semiconductors plc 2008
Electrical characteristics ( Test conditions: VIN = 3V, T
AMB
= 25
°
C unless otherwise stated (a) )
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
V
IN
Supply voltage Normal operation 2.0 12 V
V
IN
(Start) Supply voltage for start-up (b) Start-up mode 1.2 2.4 V
V
UV-
Under-voltage detection threshold
Normal operation to start-up mode VIN falling 1.8 V
V
UV+
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
I
STBY
Standby current Measured into VIN.
ADJ pin grounded 12 20 µA
V
REF
Internal reference voltage ADJ pin floating
2.0V 480 500 520 mV
TCO
(REF)
Internal reference temperature
coefficient. 50 ppm
/K
Symbol Parameter Conditions Min Typ Max Units
V
SENSE
Peak switch current sense
voltage Measured on ISENSE
pin CFB pin at 0V 45 55 65 mV
V
SENSE
(SU)
Peak switch current sense
voltage in start-up mode Measured on ISENSE
pin.
Start-up mode
VIN=1.2V 10.5 mV
I
SENSE
Sense input current Measured into
ISENSE
with pin at
0V. CFB pin at 0V
-15 -7 -1 µA
C
FB
Control loop compensation
capacitor 10 nF
V
ADJ
External dc control voltage
applied to ADJ pin to adjust
output current DC brightness
control mode 50 500 mV
V
ADJ(th)
Switching threshold of ADJ
pin Standby state to
normal operation 26 28 30 mV
TCO
(VADJ)
Temperature coefficient of
VADJ(th) +0.3 %/K
R
ADJ
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