4
LT1500/LT1501
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the full operating
temperature range.
Note 1: Feedback pin or output is held sightly above the regulated value to
force the V
C
node low and switching to stop.
Note 2: See Typical Performance Characteristics for graph of Guaranteed
Switch Voltage vs Saturation Voltage.
Note 3: Peak switch current is the guaranteed minimum value of switch
current available in normal operation. Highest calculated switch current at
full load should not exceed the minimum value shown.
Note 4: Loading on FB pin will affect NFB reference voltage. ∆V
NFB
= I
FB
/gm.
Do not exceed 10µA loading on FB when NFB is being used.
Note 5: This is the delay between sense pin current reaching its upper or
lower threshold and switch transition. Switch delay times cause peak-to-
peak inductor current to increase and therefore switching frequency to be
low. This effect will be significant for frequencies above 100kHz. See
Application Information and Typical Performance Characteristics.
Note 6: Reference voltage under all conditions includes V
IN
= 2.1V to 15V,
all loads and full temperature range.
Note 7: As with all boost regulators the output voltage of the LT1500
cannot fall to less than input voltage because of the path through the catch
diode. This means that the output voltage divider on adjustable parts will
still be generating feedback voltage at the FB pin (fixed voltage parts have
an internal switch to disconnect the divider in shutdown). If the voltage on
FB is greater than 0.6V in shutdown, the internal error amplifier will draw
current that adds to shutdown current. See graph of Shutdown Current vs
FB voltage in Typical Performance Characteristics.
TYPICAL PERFORMANCE CHARACTERISTICS
U
W
Switching Frequency
(3.3V Output)
LOAD CURRENT (mA)
0 50 100
10
FREQUENCY (kHz)
100
1000
150 200 250 300
LTC1500/01 • TPC20
10
µ
H
20
µ
H
50
µ
H
100
µ
H
BURST REGION
V
IN
= 2.3V
Switching Frequency (5V Output)
LOAD CURRENT (mA)
0 50 100
10
FREQUENCY (kHz)
100
1000
150 200 250 300
LTC1500/01 • TPC21
10
µ
H
20
µ
H
50
µ
H
100
µ
H
BURST REGION
V
IN
= 3V
Switching Frequency (12V Output)
LOAD CURRENT (mA)
0255075
FREQUENCY (kHz)
1000
100
10
100 125 150 175 200
LTC1500/01 • TPC22
10µH
50µH
20µH
100µH
BURST REGION
V
IN
= 5V
Efficiency (3.3V Output)
LOAD CURRENT (mA)
1
EFFICIENCY (%)
100
90
80
70
60
50
40
30
10 100 1000
LTC1500/01 • TPC17
T
J
= 25°C
V
IN
= 2.3V
LOW LOSS INDUCTOR
L = 100µH
L = 10µH
L = 33µH
Efficiency (5V Output)
LOAD CURRENT (mA)
1
EFFICIENCY (%)
100
90
80
70
60
50
40
30
10 100 1000
LTC1500/01 • TPC18
V
IN
= 3V
LOW LOSS INDUCTOR
L = 100µH
L = 10µH
L = 33µH
Efficiency (12V Output)
LOAD CURRENT (mA)
1
EFFICIENCY (%)
100
90
80
70
60
50
40
30
10 100 1000
LTC1500/01 • TPC19
V
IN
= 5V
LOW LOSS INDUCTOR
L = 100µH
L = 10µH
L = 33µH
