Datasheet

LTC3765
3
3765fb
For more information www.linear.com/LTC3765
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 2). V
CC
= 12V unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Gate Drivers (PG, AG, DELAY)
V
OHPG
PG High Output Voltage I
PG
= –100mA 11 V
I
PUPG
PG Peak Pull-Up Current 2.5 A
R
PDPG
PG Pull-Down Resistance I
PG
= 100mA 1.3 Ω
t
rPG
PG Rise Time 20% to 80%, C
PG
= 4.7nF 20 ns
t
fPG
PG Fall Time 20% to 80%, C
PG
= 4.7nF 20 ns
R
PUAG
AG Pull-Up Resistance I
AG
= –10mA 12 Ω
R
PDAG
AG Pull-Down Resistance I
AG
= 10mA 9 Ω
t
DAG
AG Turn-On Delay Time 180 ns
t
DPG
PG Turn-On Delay Time R
DELAY
= 0Ω
R
DELAY
= 10kΩ
R
DELAY
= 50kΩ
120
390
40
140
460
160
530
ns
ns
ns
Oscillator (FS/UV) and Soft-Start (SSFLT)
f
OSC
Oscillator Frequency R
FS
= 75kΩ
R
FS
= 10kΩ
75
430
kHz
kHz
DC
MAX
Oscillator Maximum Duty Cycle V
SSFLT
= 3.5V 70 %
V
FSUVH
FS/UV Output High V
RUN
= 1V 5 V
I
FSUV
FS/UV Pull-Up Current V
RUN
= 1V, V
FS/UV
= 1.5V 50 µA
I
SS(C)
Soft-Start Charge Current V
RUN
= 1.3V, V
SSFLT
= 1V
V
RUN
≥ 3.75V, V
SSFLT
= 1V
–4
–1.6 –0.5
µA
µA
I
SS(D)
Soft-Start Discharge Current Timing Out After Fault, V
SSFLT
= 2V 1.25 µA
V
FLTH
Fault Output High V
CC
= 6.7V 5.75 6.5 V
V
FLTD
Fault Detection Voltage 5 5.5 V
Overcurrent (I
S
+
, I
S
–
) and Direct Flux Limit (I
SMAG
, R
CORE
)
V
IS
Overcurrent Threshold V
ISTH
= V
IS
+
–V
IS
–
l
130 150 170 mV
V
ISMAG
–
I
SMAG
Limit Negative Threshold Relative to SGND or V
CC
–1.15 –1 –0.85 V
V
ISMAG
+
I
SMAG
Limit Positive Threshold Relative to SGND or V
CC
0.85 1 1.15 V
M
ISMAG
I
SMAG
Replicated Slope R
CORE
= 50kΩ, V
RUN
= 1.25V
R
CORE
= 50kΩ, V
RUN
= 6.25V
R
CORE
= 10kΩ, V
RUN
= 1.25V
R
CORE
= 10kΩ, V
RUN
= 6.25V
75
375
335
1700
mV/µs
mV/µs
mV/µs
mV/µs
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 LTC3765 is tested under pulsed-load conditions such that
T
J
≈ T
A
. The LTC3765E is guaranteed to meet specifications from
0°C to 85°C junction temperature. Specifications over the –40°C to
125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LTC3765I is guaranteed over the –40°C to 125°C operating junction
temperature range, the LTC3765H is guaranteed over the –40°C to 150°C
operating junction temperature range and the LTC3765MP is tested and
guaranteed over the –55°C to 150°C operating junction temperature range.
High junction temperatures degrade operating lifetimes; operating lifetime
is derated for junction temperature greater than 125°C. The junction
temperature (T
J
) is calculated from the ambient temperature (T
A
) and
power dissipation (P
D
) according to the formula:
T
J
= T
A
+ (P
D
• 45°C/W)
Note that the maximum ambient temperature consistent with these
specifications is determined by specific operating conditions in
conjunction with board layout, the rated package thermal impedance and
other environmental factors.
Note 3: This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions. The maximum
rated junction temperature will be exceeded when this protection is active.
Continuous operation above the specified absolute maximum operating
junction temperature may impair device reliability or permanently damage
the device.
Note 4: The linear regulator output voltage is measured with a Vishay
Siliconix Si3440DV N-channel MOSFET external pass device.
Note 5: I
CC
is the sum of current into NDRV and V
CC
.
Note 6: Rectifier forward voltage drop is the sum of the drop across the
rectifier diode and synchronous switch.