Datasheet

3
LTC1474/LTC1475
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
FB
Feedback Voltage I
LOAD
= 50mA ● 1.205 1.230 1.255 V
LTC1474/LTC1475
V
OUT
Regulated Output Voltage I
LOAD
= 50mA
LTC1474-3.3/LTC1475-3.3
● 3.234 3.300 3.366 V
LTC1474-5/LTC1475-5
● 4.900 5.000 5.100 V
I
FB
Feedback Current ● 030 nA
LTC1474/LTC1475 Only
I
SUPPLY
No Load Supply Current (Note 3) I
LOAD
= 0 (Figure 1 Circuit) 10 µA
∆V
OUT
Output Voltage Line Regulation V
IN
= 7V to 12V, I
LOAD
= 50mA 5 20 mV
Output Voltage Load Regulation I
LOAD
= 0mA to 50mA 2 15 mV
Output Ripple I
LOAD
= 10mA 50 mV
P-P
I
Q
Input DC Supply Current (Note 2) (Exclusive of Driver Gate Charge Current)
Active Mode (Switch On) V
IN
= 3V to 18V 100 175 µA
Sleep Mode (Note 3) V
IN
= 3V to 18V 9 15 µA
Shutdown V
IN
= 3V to 18V, V
RUN
= 0V 6 12 µA
R
ON
Switch Resistance I
SW
= 100mA 1.4 1.6 Ω
I
PEAK
Current Comp Max Current Trip Threshold R
SENSE
= 0Ω 325 400 mA
R
SENSE
= 1.1Ω 70 76 85 mA
V
SENSE
Current Comp Sense Voltage Trip Threshold ● 90 100 110 mV
V
HYST
Voltage Comparator Hysteresis 5mV
t
OFF
Switch Off-Time V
OUT
at Regulated Value 3.5 4.75 6.0 µs
V
OUT
= 0V 65 µs
V
LBI, TRIP
Low Battery Comparator Threshold ● 1.16 1.23 1.27 V
V
RUN
Run/ON Pin Threshold 0.4 0.7 1.0 V
V
LBI, OFF
OFF Pin Threshold (LTC1475 Only) 0.4 0.7 1.0 V
I
LBO, SINK
Sink Current into Pin 2 V
LBI
= 0V, V
LBO
= 0.4V 0.45 0.70 mA
I
RUN, SOURCE
Source Current from Pin 8 V
RUN
= 0V 0.4 0.8 1.2 µA
I
SW, LEAK
Switch Leakage Current V
IN
= 18V, V
SW
= 0V, V
RUN
= 0V 0.015 1 µA
I
LBI, LEAK
Leakage Current into Pin 3 V
LBI
= 18V, V
IN
= 18V 0 0.1 µA
I
LBO, LEAK
Leakage Current into Pin 2 V
LBI
= 2V, V
LBO
= 5V 0 0.5 µA
ELECTRICAL CHARACTERISTICS
T
A
= 25°C, V
IN
= 10V, V
RUN
= open, R
SENSE
= 0, unless otherwise noted.
The ● denotes specifications which apply over the full operating
temperature range.
Note 1: T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formulas:
LTC1474CS8/LTC1475CS8: T
J
= T
A
+ (P
D
• 110°C/W)
LTC1474CMS8/LTC1475CMS8: T
J
= T
A
+ (P
D
• 150°C/W)
Note 2: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications Information.
Note 3: No load supply current consists of sleep mode DC current (9µA
typical) plus a small switching component (about 1µA for Figure 1 circuit)
necessary to overcome Schottky diode and feedback resistor leakage.