Datasheet

LTC1871-1
4
18711fb
ELECTRICAL CHARACTERISTICS
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC1871E-1 is guaranteed to meet performance specifi cations
from 0°C to 85°C junction temperature. Specifi cations over the – 40°C
to 85°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LTC1871I-1 is guaranteed over the full –40°C to 125°C operating junction
temperature range.
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
• 110°C/W)
Note 4: The dynamic input supply current is higher due to power MOSFET
gate charging (Q
G
• f
OSC
). See Applications Information.
Note 5: The LTC1871-1 is tested in a feedback loop which servos V
FB
to
the reference voltage with the I
TH
pin forced to the midpoint of its voltage
range (0.3V ≤ V
ITH
≤ 1.2V, midpoint = 0.75V).
Note 6: In a synchronized application, the internal slope compensation
gain is increased by 25%. Synchronizing to a signifi cantly higher ratio will
reduce the effective amount of slope compensation, which could result in
subharmonic oscillation for duty cycles greater than 50%.
Note 7: Rise and fall times are measured at 10% and 90% levels.
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. V
IN
= 5V, V
RUN
= 1.5V, R
FREQ
= 80k, V
MODE/SYNC
= 0V, unless otherwise specifi ed.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Low Dropout Regulator
V
INTVCC
INTV
CC
Regulator Output Voltage V
IN
= 7.5V 5.0 5.2 5.4 V
V
IN
= 7.5V, I-Grade (Note 2)
●
5.0 5.2 5.4 V
ΔV
INTVCC
ΔV
IN1
INTV
CC
Regulator Line Regulation 7.5V ≤ V
IN
≤ 15V 8 25 mV
ΔV
INTVCC
ΔV
IN2
INTV
CC
Regulator Line Regulation 15V ≤ V
IN
≤ 30V 70 200 mV
V
LDO(LOAD)
INTV
CC
Load Regulation 0 ≤ I
INTVCC
≤ 20mA, V
IN
= 7.5V –2 –0.2 %
V
DROPOUT
INTV
CC
Regulator Dropout Voltage INTV
CC
Load = 20mA 280 mV
I
INTVCC
Bootstrap Mode INTV
CC
Supply RUN = 0V, SENSE = 5V 10 20 µA
I-Grade (Note 2)
●
30 µA
GATE Driver
t
r
GATE Driver Output Rise Time C
L
= 3300pF (Note 7) 17 100 ns
t
f
GATE Driver Output Fall Time C
L
= 3300pF (Note 7) 8 100 ns
TYPICAL PERFORMANCE CHARACTERISTICS
FB Voltage vs Temp FB Voltage Line Regulation FB Pin Current vs Temperature
TEMPERATURE (°C)
–50
FB VOLTAGE (V)
1.23
1.24
150
18711 G01
1.22
1.21
0
50
100
–25
25
75
125
1.25
V
IN
(V)
0
1.229
FB VOLTAGE (V)
1.230
1.231
5101520
18711 G02
25 30 35
TEMPERATURE (°C)
–50
0
FB PIN CURRENT (nA)
10
20
30
40
60
–25
250 50 10075
18711 G03
125 150
50