LTC1871-7
4
18717fd
FB Voltage vs Temp
FB Voltage Line Regulation
FB Pin Current vs Temperature
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 8V, V
RUN
= 1.5V, R
FREQ
= 80k, V
MODE/SYNC
= 0V, unless otherwise specified.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
UVLO INTVCC Undervoltage Lockout Threshold Rising INTV
CC
Falling INTV
CC
UVLO Hysteresis
5.6
4.6
1.0
V
V
V
∆V
INTVCC
∆V
IN1
INTV
CC
Regulator Line Regulation 8V ≤ V
IN
≤ 15V 8 25 mV
∆V
INTVCC
∆V
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
= 8V –2 –0.2 %
V
DROPOUT
INTV
CC
Regulator Dropout Voltage V
IN
= 6V, INTV
CC
Load = 20mA 280 mV
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
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-7 is guaranteed to meet performance specifications
from 0°C to 70°C junction temperature. Specifications over the –40°C
to 85°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LTC1871I-7 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
• 120°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 LTC1871-7 is tested in a feedback loop that servos V
FB
to the
reference voltage with the I
TH
pin forced to a voltage between 0V and 1.4V
(the no load to full load operating voltage range for the I
TH
pin is 0.3V to
1.23V).
Note 6: In a synchronized application, the internal slope compensation
gain is increased by 25%. Synchronizing to a significantly 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.
Typical perForMance characTerisTics
TEMPERATURE (°C)
–50
FB VOLTAGE (V)
1.23
1.24
150
18717 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
5 10 15 20
18717 G02
25 30 35
TEMPERATURE (°C)
–50
0
FB PIN CURRENT (nA)
10
20
30
40
60
–25
250 50 10075
18717 G03
125 150
50
