4
LTC1624
TYPICAL PERFOR
M
A
N
CE CHARACTERISTICS
U
W
V
ITH
/RUN (V)
1.2
0.8
2.4
0
0
I
OUT(MAX)
I
OUT
(a)
1624 G01
I
OUT(MAX)
SHUTDOWN
ACTIVE
MODE
V
ITH
vs Output Current
TEMPERATURE (
°
C)
–40
I
TH
/RUN PIN SOURCE CURRENT WITH V
ITH
= 1V (
µ
A)
I
TH
/RUN PIN SOURCE CURRENT WITH V
ITH
= 0V (
µ
A)
300
250
200
150
100
50
0
5
4
3
2
1
0
35
85
1624 G14
–15
10
60
110
135
I
TH
/RUN = 1V
I
TH
/RUN = 0V
I
TH
/RUN Pin Source Current vs
Temperature
I
ITH
vs V
ITH
I
ITH
(
µ
A)
200
150
50
0
3
V
ITH
(V)
1.2
2.4
0.8
0
(b)
1624 G02
SHUTDOWN
ACTIVE
MODE
Frequency vs Feedback Voltage
FEEDBACK VOLTAGE
0
FREQUENCY (kHz)
250
200
150
100
50
0
1.00
1624 G03
0.25
0.50
0.75
1.25
TEMPERATURE (
°
C)
–40
CURRENT SENSE THRESHOLD (mV)
170
168
166
164
162
160
158
156
154
152
150
10
60
85
1448 G13
–15
35
110
135
Maximum Current Sense
Threshold vs Temperature
TEMPERATURE (
°
C)
–40
FREQUENCY (kHz)
250
200
150
100
50
0
10
60
85
1448 G12
–15
35
110
135
V
OUT
IN REGULATION
V
FB
= 0V
PI
N
FU
N
CTIO
N
S
U
U
U
SENSE
–
(Pin 1): Connects to the (–) input for the current
comparator. Built-in offsets between the SENSE
–
and V
IN
pins in conjunction with R
SENSE
set the current trip thresh-
olds. Do not pull this pin more than 15V below V
IN
or more
than 0.3V below ground.
I
TH
/RUN (Pin 2): Combination of Error Amplifier Compen-
sation Point and Run Control Inputs. The current com-
parator threshold increases with this control voltage.
Nominal voltage range for this pin is 1.19V to 2.4V. Forcing
this pin below 0.8V causes the device to be shut down. In
shutdown all functions are disabled and TG pin is held low.
V
FB
(Pin 3): Receives the feedback voltage from an exter-
nal resistive divider across the output.
GND (Pin 4): Ground. Connect to the (–) terminal of C
OUT
,
the Schottky diode and the (–) terminal of C
IN
.
SW (Pin 5): Switch Node Connection to Inductor. In step-
down applications the voltage swing at this pin is from a
Schottky diode (external) voltage drop below ground to
V
IN
.
Operating Frequency vs
Temperature
