Datasheet

3
LTC3704
3704fb
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
reliabilty and lifetime.
Note 2: The LTC3704E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. The LTC3704I is guaranteed over the full
–40°C to 125°C operating 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 LTC3704 is tested in a feedback loop that servos V
NFB
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.
The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C.
V
IN
= V
INTVCC
= 5V, V
RUN
= 1.5V, R
FREQ
= 80k, V
MODE/SYNC
= 0V, unless otherwise specified.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Oscillator
f
OSC
Oscillator Frequency R
FREQ
= 80k 250 300 350 kHz
Oscillator Frequency Range 50 1000 kHz
D
MAX
Maximum Duty Cycle 87 92 97 %
f
SYNC/
f
OSC
Recommended Maximum Synchronized f
OSC
= 300kHz (Note 6) 1.25 1.30
Frequency Ratio
t
SYNC(MIN)
MODE/SYNC Minimum Input Pulse Width V
SYNC
= 0V to 5V 25 ns
t
SYNC(MAX)
MODE/SYNC Maximum Input Pulse Width V
SYNC
= 0V to 5V 0.8/f
OSC
ns
V
IL(MODE)
Low Level MODE/SYNC Input Voltage 0.3 V
V
IH(MODE)
High Level MODE/SYNC Input Voltage 1.2 V
R
MODE/SYNC
MODE/SYNC Input Pull-Down Resistance 50 kΩ
V
FREQ
Nominal FREQ Pin Voltage 0.62 V
Low Dropout Regulator
V
INTVCC
INTV
CC
Regulator Output Voltage V
IN
= 7.5V 5.0 5.2 5.4 V
ΔV
INTVCC
INTV
CC
Regulator Line Regulation 7.5V ≤ V
IN
≤ 15V 8 25 mV
ΔV
IN1
ΔV
INTVCC
INTV
CC
Regulator Line Regulation 15V ≤ V
IN
≤ 30V 70 200 mV
ΔV
IN2
V
LDO(LOAD)
INTV
CC
Load Regulation V
IN
= 7.5V, 0 ≤ I
INTVCC
≤ 20mA –2 – 0.2 %
V
DROPOUT
INTV
CC
Regulator Dropout Voltage V
INTVCC
= Open, INTV
CC
Load = 20mA 280 mV
I
INTVCC
Bootstrap Mode INTV
CC
Supply RUN = 0V, SENSE = 5V 10 20 μA
Current in Shutdown
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
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