LTC1872
3
1872fa
For more information
www.linear.com/LTC1872
Typical perForMance characTerisTics
Reference Voltage
vs Temperature
Undervoltage Lockout Trip
Voltage vs Temperature
Shutdown Threshold
vs Temperature
Maximum Current Sense Trip
Voltage vs Duty Cycle
Normalized Oscillator Frequency
vs Temperature
TEMPERATURE (°C)
–55
775
V
FB
VOLTAGE (mV)
780
790
795
800
825
810
–15
25 45
125
1872 G01
785
815
820
805
–35
5
65 85 105
V
IN
= 4.2V
TEMPERATURE (°C)
–55
–10
NORMALIZED FREQUENCY (%)
–8
–4
–2
0
10
4
–15
25 45
125
1872 G02
–6
6
8
2
–35
5
65 85 105
V
IN
= 4.2V
TEMPERATURE (°C)
–55
1.84
UVLO TRIP VOLTAGE (V)
1.88
1.96
2.00
2.04
2.24
2.12
–15
25 45
125
1872 G03
1.92
2.16
2.20
2.08
–35
5
65 85 105
V
IN
FALLING
DUTY CYCLE (%)
20
30
V
IN
– V
SENSE
– (mV)
100
1872 G04
40
50
60
70
80
90
130
120
110
100
90
80
70
60
50
V
IN
= 4.2V
T
A
= 25°C
TEMPERATURE (°C)
–55
200
I
TH
/RUN VOLTAGE (mV)
240
320
360
400
600
480
–15
25 45
125
1872 G05
280
520
560
440
–35
5
65 85 105
V
IN
= 4.2V
pin FuncTions
I
TH
/RUN (Pin 1):
This pin performs two functions. It
serves as the error amplifier compensation point as well
as the run control input. Nominal voltage range for this
pin is 0.7V to 1.9V. Forcing this pin below 0.35V causes
the device to be shut down. In shutdown all functions are
disabled and the NGATE pin is held low.
GND (Pin 2):
Ground Pin.
V
FB
(Pin 3):
Receives the feedback voltage from an external
resistive divider across the output.
SENSE
–
(Pin 4):
The Negative Input to the Current Com-
parator.
V
IN
(Pin 5):
Supply Pin. Must be closely decoupled to
GND Pin 2.
NGATE (Pin 6):
Gate Drive for the External N-Channel
MOSFET. This pin swings from 0V to V
IN
.
