LTC1779 LINER [Linear Technology], LTC1779 Datasheet - Page 2

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

ABSOLUTE AXI U RATI GS
(Note 1)
Input Supply Voltage (V
SENSE
V
SW Peak Output Current (< 10 s) .......................... 0.5A
Storage Ambient Temperature Range ... – 65 C to 150 C
Operating Temperature Range (Note 2) ...–40 C to 85 C
Junction Temperature (Note 3) ............................. 150 C
Lead Temperature (Soldering, 10 sec).................. 300 C
LTC1779
ELECTRICAL CHARACTERISTICS
range, otherwise specifications are at T
PARAMETER
Input DC Supply Current
Undervoltage Lockout Threshold
Shutdown Threshold (at I
Start-Up Current Source
Regulated Feedback Voltage
Output Voltage Line Regulation
Output Voltage Load Regulation
V
Overvoltage Protect Threshold
Overvoltage Protect Hysteresis
Overtemperature Protect Threshold
Overtemperature Protect Hysteresis
Oscillator Frequency
R
Peak Current Sense Voltage
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC1779E is guaranteed to meet performance specifications
from 0 C to 70 C. Specifications over the – 40 C to 85 C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3: T
dissipation P
2
FB
DS(ON)
FB
Normal Operation
Shutdown
UVLO
T
Input Current
, I
J
= T
TH
of Internal P-Channel FET
J
–
A
/RUN Voltages ..............................– 0.3V to 2.4V
, SW Voltages .................. – 0.3V to (V
is calculated from the ambient temperature T
+ (P
D
according to the following formula:
D
•
J
C/W)
W
TH
/RUN)
IN
).........................– 0.3V to 10V
W W
A
= 25 C. V
A
CONDITIONS
Typicals at V
V
V
V
(Note 5) 0 C to 70 C
(Note 5) – 40 C to 85 C
2.5V V
I
I
(Note 5)
Measured at V
V
V
V
(Note 6)
and power
TH
TH
U
IN
IN
ITH
FB
FB
IN
IN
2.5V V
2.5V V
V
/RUN Sinking 5 A (Note 5)
/RUN Sourcing 5 A (Note 5)
IN
Falling
Rising
= 4.2V, I
= 4.2V unless otherwise specified. (Note 2)
= 0.8V
= 0V
/RUN = 0V
IN
< UVLO Threshold
+ 0.3V)
IN
IN
IN
The
SW
IN
9.8V (Note 5)
FB
= 4.2V (Note 4)
9.8V
9.8V, V
= 100mA
denotes specifications that apply over the full operating temperature
ITH
PACKAGE/ORDER I FOR ATIO
Consult LTC Marketing for parts specified with wider operating temperature
ranges.
Note 4: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency.
Note 5: The LTC1779 is tested in a feedback loop that servos V
output of the error amplifier.
Note 6: Peak current sense voltage is reduced dependent upon duty cycle
to a percentage of value as given in Figure 2.
/RUN = 0V
I
TH
/RUN 1
GND 2
V
T
FB
JMAX
6-LEAD PLASTIC SOT-23
3
= 150 C,
S6 PACKAGE
TOP VIEW
JA
= 230 C/ W
6 SW
5 V
4 SENSE
IN
0.780
0.770
0.820
1.60
0.15
0.25
MIN
500
– 3
–
U
0.325
0.800
0.800
0.860
0.85
TYP
135
170
550
100
120
2.0
2.1
0.5
2.5
2.5
S6 PART MARKING
30
15
8
7
0
5
ORDER PART
LTC1779ES6
W
NUMBER
0.820
0.830
0.895
MAX
LTLP
0.85
240
650
2.5
0.5
1.4
22
13
25
3
FB
to the
mV/ A
mV/ A
UNITS
U
mV/V
kHz
kHz
mV
mV
nA
A
A
A
V
V
V
A
V
V
V
C
C