LT1108
W W W
U
ABSOLUTE AXI U RATI GS
Supply Voltage (VIN) ............................................... 36V
SW1 Pin Voltage (VSW1) ......................................... 50V
SW2 Pin Voltage (VSW2) ............................ –0.5V to VIN
Feedback Pin Voltage (LT1108) ............................. 5.5V
Sense Pin Voltage (LT1108, -5, -12) ...................... 36V
Maximum Power Dissipation ............................ 500mW
Maximum Switch Current ...................................... 1.5A
Operating Temperature Range .................... 0°C to 70°C
Storage Temperature Range ................ –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
W
U
/O
PACKAGE RDER I FOR ATIO
ORDER PART
ORDER PART
TOP VIEW
TOP VIEW
NUMBER
NUMBER
I
1
2
3
4
FB (SENSE*)
I
1
2
3
4
FB (SENSE*)
8
7
6
5
8
7
6
5
LIM
LIM
LT1108CN8
LT1108CN8-5
LT1108CN8-12
LT1108CS8
LT1108CS8-5
LT1108CS8-12
V
IN
SET
A0
V
IN
SET
A0
SW1
SW2
SW1
SW2
GND
GND
S8 PART MARKING
S8 PACKAGE
8-LEAD PLASTIC SOIC
N8 PACKAGE
8-LEAD PLASTIC DIP
*FIXED VERSIONS
*FIXED VERSIONS
1108
10805
10812
TJMAX = 90°C, θJA = 130°C/W
TJMAX = 90°C, θJA = 150°C/W
ELECTRICAL CHARACTERISTICS TA = 25°C, VIN = 3V, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
Switch OFF
No Load
MIN
TYP
MAX
UNITS
I
Quiescent Current
●
110
150
µA
Q
Quiescent Current, Boost Mode Configuration
LT1108-5
LT1108-12
135
250
µA
µA
V
V
Input Voltage
Step-Up Mode
●
●
2
12.6
30.0
V
V
IN
Step-Down Mode
Comparator Trip Point Voltage
Output Sense Voltage
LT1108 (Note 1)
●
1.2
1.245
1.3
V
LT1108-5 (Note 2)
LT1108-12 (Note 2)
●
●
4.75
11.4
5
12
5.25
12.6
V
V
OUT
Comparator Hysteresis
Output Hysteresis
LT1108
●
5
10
mV
LT1108-5
LT1108-12
●
●
20
50
40
100
mV
mV
f
t
Oscillator Frequency
Duty Cycle
●
●
●
●
●
●
14
63
28
19
70
25
78
kHz
%
OSC
ON
Full Load, Step-Up Mode
Switch-ON Time
I
Tied to V , Step-Up Mode
36
48
µs
nA
nA
V
LIM
IN
Feedback Pin Bias Current
Set Pin Bias Current
Gain Block Output Low
Reference Line Regulation
LT1108, V = 0V
10
50
FB
V
SET
= V
20
100
0.4
REF
V
V
I
= 100µA, V = 1V
SET
0.15
OL
SINK
2V ≤ V ≤ 5V
●
●
0.20
0.02
0.400
0.075
%/V
%/V
IN
5V ≤ V ≤ 30V
IN
SW
Voltage, Step-Up Mode
V
IN
V
IN
= 3V, I = 650mA
●
0.5
0.8
0.65
1.00
V
V
SAT
SAT
SW
= 5V, I = 1A
SW
2
Linear [ Linear ]
