LTC1872
2
1872fa
For more information www.linear.com/LTC1872
pin conFiguraTionabsoluTe MaxiMuM raTings
Input Supply Voltage (V
IN
) ......................... –0.3V to 10V
SENSE
–
, NGATE Voltages ............. –0.3V to (V
IN
+ 0.3V)
V
FB
, I
TH
/RUN Voltages .............................. –0.3V to 2.4V
NGATE Peak Output Current (< 10µs) ........................ 1A
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
(Note 1)
TH
/RUN 1
GND 2
V
FB
3
6 NGATE
5 V
IN
4 SENSE
S6 PACKAGE
T
JMAX
= 150°C, θ
JA
= 230°C/W
orDer inForMaTion
elecTrical characTerisTics
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC1872E 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
JA
°C/W)
PARAMETER CONDITIONS MIN TYP MAX UNITS
Input DC Supply Current
Normal Operation
Sleep Mode
Shutdown
UVLO
Typicals at V
IN
= 4.2V (Note 4)
2.4V ≤ V
IN
≤ 9.8V
2.4V ≤ V
IN
≤ 9.8V
2.4V ≤ V
IN
≤ 9.8V, V
ITH
/RUN = 0V
V
IN
< UVLO Threshold
270
230
8
6
420
370
22
10
µA
µA
µA
µA
Undervoltage Lockout Threshold V
IN
Falling
V
IN
Rising
l
1.55
1.85
2.00
2.10
2.35
2.40
V
V
Shutdown Threshold (at I
TH
/RUN)
l
0.15 0.35 0.55 V
Start-Up Current Source V
ITH
/RUN = 0V 0.25 0.5 0.85 µA
Regulated Feedback Voltage 0°C to 70°C(Note 5)
–40°C to 85°C(Note 5)
l
l
0.780
0.770
0.800
0.800
0.820
0.830
V
V
V
FB
Input Current (Note 5) 10 50 nA
Oscillator Frequency V
FB
= 0.8V 500 550 650 kHz
Gate Drive Rise Time C
LOAD
= 3000pF 40 ns
Gate Drive Fall Time C
LOAD
= 3000pF 40 ns
Peak Current Sense Voltage (Note 6) 114 120 mV
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 4.2V unless otherwise specified. (Note 2)
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC1872ES6#PBF LTC1872ES6#TRPBF LTMK 6-Lead Plastic SOT-23 –40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on nonstandard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
Note 4:
Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency.
Note 5: The LTC1872 is tested in a feedback loop that servos V
FB
to the
output of the error amplifier.
Note 6: Guaranteed by design at duty cycle = 30%. Peak current sense
voltage is V
REF
/6.67 at duty cycle <40%, and decreases as duty cycle
increases due to slope compensation as shown in Figure 2.
