LTC1142-ADJ Linear Technology, LTC1142-ADJ Datasheet - Page 5

• Manufacturer Part Number: LTC1142-ADJ
• Description: Dual High Efficiency Synchronous Step-Down Switching Regulators
• Manufacturer: Linear Technology

TYPICAL PERFOR
PI FU CTIO S
LTC1142/LTC1142HV
SENSE
Current Comparator. A built-in offset between Pins 1 and
28 in conjunction with R
threshold for the 3.3V section.
SHUTDOWN 3 (Pin 2): When grounded, the 3.3V section
operates 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
Do not “float” Pin 2.
2.1
1.8
1.5
1.2
0.9
0.6
0.3
28
24
20
16
12
U
8
4
0
0
20
DC Supply Current
Gate Charge Supply Current
0
+
PER REGULATOR BLOCK
NOT INCLUDING
GATE CHARGE CURRENT
PINS 10, 24
3 (Pin 1): The (+) Input to the 3.3V Section
2
OPERATING FREQUENCY (kHz)
U
80
4
Q
N
INPUT VOLTAGE (V)
+ Q
6
P
140
= 100nC
ACTIVE MODE
SLEEP MODE
8
Q
U
N
10
+ Q
200
P
12
= 50nC
SENSE3
W
14
260
1142 G10
A
16
1142 G07
U
18
sets the current trip
CE
C
HARA TERISTICS
20
18
16
14
12
10
80
70
60
50
40
30
20
10
8
6
4
2
0
0
0
Supply Current in Shutdown
Off-Time vs Output Voltage
0
r
, t
PER REGULATOR BLOCK
PINS 10, 24
V
SHUTDOWN
2
f
V
< 1 s.
OUT
1
C
4
OUTPUT VOLTAGE (V)
= 3.3V
INPUT VOLTAGE (V)
6
= 2V
2
8
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
10
LTC1142/LTC1142L/LTC1142HV
V
3
OUT
V
12
SENSE
= 5V
14
4
= V
16
OUT
1142 G08
1142 G11
IN3
18
5
.
175
150
125
100
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
75
50
25
0
0
0
Operating Frequency vs
V
0
Current Sense Threshold Voltage
IN
V
OUT
– V
2
20
= 5V
OUT
V
IN
TEMPERATURE (°C)
4
– V
40
OUT
25°C
6
VOLTAGE (V)
0°C
60
THRESHOLD
THRESHOLD
MAXIMUM
MINIMUM
70°C
8
80
10
1142 G09
1142 G12
5
100
12