Datasheet

LT1768
2
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
I
Q
Supply Current 9V< V
VIN
< 24V ● 78 mA
I
SHDN
Supply Current in Shutdown V
SHDN
= 0V ● 65 100 µA
SHDN Pin Pull-Up Current V
SHDN
= 0V ● 4712 µA
SHDN Threshold Voltage V
SHDN
Off to On ● 0.6 1.26 1.8 V
SHDN Threshold Hysteresis ● 100 200 300 mV
V
IN
Undervoltage Lockout V
IN
Off to On ● 7.2 7.9 8.2 V
V
IN
Undervoltage Lockout V
IN
On to Off ● 7.1 7.4 7.6 V
V
REF
REF Voltage I
REF
= –1mA ● 4.9 5 5.1 V
REF Line Regulation ∆V
VIN
8V to 24V I
REF
= –1mA ● 720 mV
REF Load Regulation ∆I
REF
–1mA to –10mA ● 10 20 mV
V
RMAX
R
MAX
Pin Voltage ● 1.225 1.25 1.275 V
V
RMIN
R
MIN
Pin Voltage ● 1.22 1.26 1.30 V
FSW Switching Frequency V
PROG
= 0.75V, V
SENSE
= 0V ● 300 350 410 kHz
Maximum Duty Cycle V
PROG
= 0.75V, V
SENSE
= 0V 93 %
Minimum ON Time V
PROG
= 0.75V, V
SENSE
= 150mV 125 ns
I
PROG
PROG Pin Input Bias Current V
PROG
= 5V ● 100 500 nA
V
PROG
PROG Pin Voltage for Zero Lamp Current (Note 2) ● 0.45 0.5 0.55 V
PROG Pin Voltage for Minimum Lamp Current (Note 3)
● 0.9 1 1.1 V
PROG Pin Voltage for Maximum Lamp Current (Note 4) ● 3.8 4 4.2 V
Input Voltage (V
IN
Pin) ............................................ 28V
SHDN Pin Voltage.................................................... 28V
FAULT Pin Voltage ................................................... 28V
PROG Pin Voltage................................................... 5.5V
PWM Pin Voltage.................................................... 4.5V
C
T
Pin Voltage ........................................................ 4.5V
SENSE Pin Voltage .................................................... 1V
DIO1, DIO2 Input Current ................................... ±50mA
R
MAX
Pin Source Current..................................... 750µA
R
MIN
Pin Source Current ..................................... 750µA
V
REF
Pin Source Current ....................................... 10mA
Operating Junction Temperature Range
LT1768C................................................ 0°C to 125°C
LT1768I ............................................ –40°C to 125°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering 10 sec)...................300°C
ORDER PART
NUMBER
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ABSOLUTE AXI U RATI GS
W
WW
U
PACKAGE/ORDER I FOR ATIO
UUW
(Note 1)
ELECTRICAL CHARACTERISTICS
T
JMAX
= 125°C, θ
JA
= 100°C/W
1
2
3
4
5
6
7
8
TOP VIEW
GN PACKAGE
16-LEAD PLASTIC SSOP
16
15
14
13
12
11
10
9
PGND
DI01
DI02
SENSE
VC
AGND
C
T
PROG
GATE
V
IN
V
REF
FAULT
SHDN
R
MIN
R
MAX
PWM
LT1768CGN
LT1768IGN
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C, V
VIN
= 12V, I
DIO1/2
= 250µA, V
PROG
= 0V, V
PWM
= 2.5V, I
RMAX
= –100µA,
I
RMIN
= –100µA, unless otherwise specified.
GN PART
MARKING
1768
1768I