LTC1148LCS Linear Technology, LTC1148LCS Datasheet - Page 5

• Manufacturer Part Number: LTC1148LCS
• Description: IC SW REG STEP-DWN HI-EFF 14SOIC
• Manufacturer: Linear Technology
• Type: Step-Down (Buck)r

Specifications of LTC1148LCS

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: Adjustable
• Current - Output: 50mA
• Frequency - Switching: 250kHz
• Voltage - Input: 3.5 ~ 20 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 14-SOIC (3.9mm Width), 14-SOL
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -

PI FU CTIO S
P-DRIVE (Pin 1): High Current Drive for Top P-Channel
MOSFET. Voltage swing at this pin is from V
NC (Pin 2): No Connection. Can connect to power ground.
V
to power ground Pin 12.
C
the operating frequency. The actual frequency is also
dependent upon the input voltage.
INTV
Can be decoupled to signal ground. Do not externally load
this pin.
I
comparator threshold increases with the Pin 6 voltage.
SENSE
which sets the output voltage in LTC1148-3.3 and
LTC1148-5 versions. Pin 7 is also the (–) input for the
current comparator.
SENSE
A built-in offset between Pins 7 and 8 in conjunction with
R
TYPICAL PERFOR
TH
IN
T
SENSE
(Pin 4): External capacitor C
16
12
28
24
20
U
(Pin 6): Gain Amplifier Decoupling Point. The current
8
0
(Pin 3): Main Supply Pin. Must be closely decoupled
4
20
CC
Gate Charge Supply Current
–
+
(Pin 5): Internal Supply Voltage, Nominally 3.3V.
sets the current trip threshold.
(Pin 8): The (+) Input to the Current Comparator.
(Pin 7): Connects to internal resistive divider
OPERATING FREQUENCY (kHz)
U
80
Q
N
+ Q
P
140
= 100nC
Q
U
N
+ Q
200
P
= 50nC
W
LTC1148 • TPC07
T
260
A
from Pin 4 to ground sets
U
CE
C
HARA TERISTICS
IN
50
30
80
70
60
40
20
10
0
to ground.
Off Time vs V
0
LTC1148-3.3
C
1
OUTPUT VOLTAGE (V)
OUT
2
V
serves as the feedback pin from an external resistive
divider used to set the output voltage. On LTC1148-3.3
and LTC1148-5 versions this pin is not used.
SHUTDOWN (Pin 10): When grounded, the LTC1148
series operates normally. Pulling Pin 10 high holds both
MOSFETs off and puts the LTC1148 series in micropower
shutdown mode. Requires CMOS logic signal with t
t
SGND (Pin 11): Small-Signal Ground. Must be routed
separately from other grounds to the (–) terminal of C
PGND (Pin 12): Driver Power Ground. Connects to source
of N-channel MOSFET and the (–) terminal of C
NC (Pin 13): No Connection. Can connect to power ground.
N-DRIVE (Pin 14): High Current Drive for Bottom
N-Channel MOSFET. Voltage swing at Pin 14 is from
ground to V
F
FB
< 1µs, should not be left floating.
LTC1148-5
3
(Pin 9): For the LTC1148 adjustable version, Pin 9
V
SENSE
LTC1148 • TPC08
–
4
= V
IN
OUT
.
LTC1148-3.3/LTC1148-5
5
100
175
150
125
75
50
25
0
0
Current Sense Threshold Voltage
20
THRESHOLD
MINIMUM
TEMPERATURE (°C)
40
LTC1148
THRESHOLD
60
MAXIMUM
IN
LTC1148 • TPC09
80
.
114835fd
OUT
5
100
R
,
.