LTC1779 LINER [Linear Technology], LTC1779 Datasheet - Page 3

• Manufacturer Part Number: LTC1779
• Description: 250mA Current Mode Step-Down DC/DC Converter in ThinSOT
• Manufacturer: LINER [Linear Technology]

TYPICAL PERFOR A CE CHARACTERISTICS
PI FU CTIO S
I
serves as the error amplifier compensation point as well as
the run control input. The current comparator threshold
increases with this control voltage. Nominal voltage range
for this pin is 0.7V to 1.9V. Forcing this pin below 0.325V
causes the device to be shut down. In shutdown all
functions are disabled and the internal P-channel MOSFET
is turned off. The SW pin will be high impedance.
GND (Pin 2): Ground Pin.
V
nal resistive divider across the output.
TH
FB
825
820
815
810
805
800
795
790
785
780
775
600
560
520
480
440
400
360
320
280
240
200
/RUN (Pin 1): This pin performs two functions. It
U
(Pin 3): Receives the feedback voltage from an exter-
–55
–55
Shutdown Threshold
vs Temperature
Reference Voltage
vs Temperature
V
V
IN
IN
–35
–35
= 4.2V
= 4.2V
U
–15
–15
TEMPERATURE ( C)
TEMPERATURE ( C)
5
5
25
25
U
45
45
65
65
W
85 105
85 105
1779 G01
1779 G04
U
125
125
1.85
1.70
1.55
1.40
1.25
1.10
0.95
0.80
0.65
0.50
0.35
–12
–15
–3
–6
–9
15
12
9
6
3
0
–55
2
Normalized Oscillator Frequency
vs Temperature
R
vs Input Voltage
V
DS(ON)
IN
–35
= 4.2V
3
–15
of Internal P-Channel FET
4
TEMPERATURE ( C)
INPUT VOLTAGE (V)
5
T
T
A
5
A
= 25 C
T
25
= 125 C
A
= –55 C
6
SENSE
parator. Can be connected to V
peak current of 250mA. Connecting a resistor between
SENSE
Applications Information for specifying resistor value.)
V
Pin 2.
SW (Pin 6): Switching Node and Drain of Internal
P-Channel Power MOSFET. Connects to external induc-
tor and catch diode.
45
IN
7
(Pin 5): Supply Pin. Must be closely decoupled to GND
65
I
SENSE
SW
–
–
8
85 105
= 100mA
(Pin 4): The Negative Input to the Current Com-
and V
–
9
1779 G05
1779 G02
= V
IN
125
10
IN
specifies a lower peak current. (See
2.20
2.16
2.12
2.08
2.04
2.00
1.96
1.92
1.88
1.84
1.80
1.85
1.70
1.55
1.40
1.25
1.10
0.95
0.80
0.65
0.50
0.35
–55
–55
Undervoltage Lockout Trip
Voltage vs Temperature
R
vs Temperature
I
SENSE
V
SW
DS(ON)
IN
–35
–35
FALLING
= 100mA
–
–15
–15
= V
IN
of Internal P-Channel FET
V
IN
IN
TEMPERATURE ( C)
TEMPERATURE ( C)
V
5
= 2.4V
IN
5
for default minimum
V
= 6V
IN
25
25
= 9.8V
V
45
LTC1779
IN
45
= 4.2V
65
65
V
IN
85 105
85 105 125
= 8.4V
1779 G03
1779 G06
3
125