LTC1142/LTC1142L/LTC1142HV
TYPICAL PERFOR A CE CHARACTERISTICS
DC Supply Current
2.1
1.8
SUPPLY CURRENT (mA)
1.5
1.2
0.9
0.6
0.3
0
0
2
4
6
8 10 12 14
INPUT VOLTAGE (V)
16
18
SLEEP MODE
SUPPLY CURRENT (µA)
NORMALIZED FREQUENCY
ACTIVE MODE
PER REGULATOR BLOCK
NOT INCLUDING
GATE CHARGE CURRENT
PINS 10, 24
Gate Charge Supply Current
28
24
GATE CHARGE CURRENT (mA)
SENSE VOLTAGE (mV)
20
16
12
8
Q
N
+ Q
P
= 100nC
OFF-TIME (µs)
Q
N
+ Q
P
= 50nC
4
0
20
80
200
260
140
OPERATING FREQUENCY (kHz)
1142 G10
PI FU CTIO S
LTC1142/LTC1142HV
SENSE
+
3 (Pin 1):
The (+) Input to the 3.3V Section
Current Comparator. A built-in offset between Pins 1 and
28 in conjunction with R
SENSE3
sets the current trip
threshold for the 3.3V section.
SHDN3 (Pin 2):
When grounded, the 3.3V section oper-
ates normally. Pulling Pin 2 high holds both MOSFETs off
and puts the 3.3V section in micropower shutdown mode.
Requires CMOS logic-level signal with t
r
, t
f
< 1µs. Do not
“float” Pin 2.
SGND3 (Pin 3):
The 3.3V section small-signal ground
must be routed separately from other grounds to the (–)
terminal of the 3.3V section output capacitor.
PGND3 (Pin 4):
The 3.3V section driver power ground
connects to source of N-channel MOSFET and the (–)
terminal of the 3.3V section input capacitor.
NC (Pin 5):
No Connection.
NDRIVE 3 (Pin 6):
High Current Drive for Bottom N-Channel
MOSFET, 3.3V Section. Voltage swing at Pin 6 is from
ground to V
IN3
.
U W
1142 G07
Supply Current in Shutdown
20
18
16
14
12
10
8
6
4
2
0
0
2
4
6
8 10 12 14
INPUT VOLTAGE (V)
16
18
PER REGULATOR BLOCK
PINS 10, 24
V
SHUTDOWN
= 2V
Operating Frequency vs
V
IN
– V
OUT
1.6
V
OUT
= 5V
1.4
0°C
1.2
1.0
0.8
0.6
0.4
0.2
0
0
2
4
6
8
10
12
1142 G09
70°C
25°C
V
IN
– V
OUT
VOLTAGE (V)
1142 G08
Off-Time vs Output Voltage
80
70
60
50
40
30
20
10
0
0
V
OUT
= 3.3V
1
3
4
2
OUTPUT VOLTAGE (V)
5
1142 G11
Current Sense Threshold Voltage
175
150
125
100
75
50
25
0
0
20
60
40
TEMPERATURE (°C)
80
100
1142 G12
V
SENSE
= V
OUT
MAXIMUM
THRESHOLD
V
OUT
= 5V
MINIMUM
THRESHOLD
U
U
U
5
LINER [ LINEAR TECHNOLOGY ]
