Datasheet

2
LTC1779
(Note 1)
Input Supply Voltage (V
IN
).........................–0.3V to 10V
SENSE
–
, SW Voltages .................. –0.3V to (V
IN
+ 0.3V)
V
FB
, I
TH
/RUN Voltages ..............................–0.3V to 2.4V
SW Peak Output Current (<10µs).......................... 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
T
JMAX
= 150°C, θ
JA
= 230°C/ W
S6 PART MARKING
ORDER PART
NUMBER
LTC1779ES6
LTLP
The ● denotes specifications that apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
IN
= 4.2V unless otherwise specified. (Note 2)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Input DC Supply Current Typicals at V
IN
= 4.2V (Note 4)
Normal Operation 2.5V ≤ V
IN
≤ 9.8V 135 240 µA
Shutdown 2.5V ≤ V
IN
≤ 9.8V, V
ITH
/RUN = 0V 8 22 µA
UVLO V
IN
< UVLO Threshold 7 13 µA
Undervoltage Lockout Threshold V
IN
Falling ● 1.60 2.0 V
V
IN
Rising 2.1 2.5 V
Shutdown Threshold (at I
TH
/RUN) ● 0.15 0.325 0.5 V
Start-Up Current Source V
ITH
/RUN = 0V 0.25 0.5 0.85 µA
Regulated Feedback Voltage (Note 5) 0°C to 70°C ● 0.780 0.800 0.820 V
(Note 5) –40°C to 85°C
● 0.770 0.800 0.830 V
Output Voltage Line Regulation 2.5V ≤ V
IN
≤ 9.8V (Note 5) –3 0 3 mV/V
Output Voltage Load Regulation I
TH
/RUN Sinking 5µA (Note 5) 2.5 mV/µA
I
TH
/RUN Sourcing 5µA (Note 5) 2.5 mV/µA
V
FB
Input Current (Note 5) 5 25 nA
Overvoltage Protect Threshold Measured at V
FB
0.820 0.860 0.895 V
Overvoltage Protect Hysteresis 30 mV
Overtemperature Protect Threshold 170 °C
Overtemperature Protect Hysteresis 15 °C
Oscillator Frequency V
FB
= 0.8V 500 550 650 kHz
V
FB
= 0V 100 kHz
R
DS(ON)
of Internal P-Channel FET V
IN
= 4.2V, I
SW
= 100mA 0.85 1.4 Ω
Peak Current Sense Voltage (Note 6) 120 mV
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
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formula:
T
J
= T
A
+ (P
D
• θ
J
°C/W)
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
FB
to the
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.
I
TH
/RUN 1
GND 2
V
FB
3
6 SW
5 V
IN
4 SENSE
–
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6-LEAD PLASTIC SOT-23
ABSOLUTE AXI U RATI GS
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PACKAGE/ORDER I FOR ATIO
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ELECTRICAL CHARACTERISTICS
Consult LTC Marketing for parts specified with wider operating temperature
ranges.