Datasheet

3
LTC1698
1698f
The ● indicates specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
DD
= 8V, unless otherwise noted. (Note 4)
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired. All voltages refer to GND.
Note 2: The LTC1698 incorporates a 5V linear regulator to power internal
circuitry. Driving these pins above 5.3V may cause excessive current flow.
Guaranteed by design and not subject to test.
Note 3: The LTC1698E is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. For guaranteed performance to
specifications over the –40°C to 85°C range, the LTC1698I is available.
Note 4: All currents into device pins are positive; all currents out of the
device pins are negative. All voltages are referenced to ground unless
otherwise specified. For applications with V
DD
< 7V, refer to the Typical
Performance Characteristics.
Note 5: Supply current in active operation is dominated by the current
needed to charge and discharge the external FET gates. This will vary with
the LTC1698 operating frequency, supply voltage and the external FETs
used.
Note 6: This parameter is guaranteed by correlation and is not tested.
Note 7: V
FB
is tested in an op amp feedback loop which servos V
FB
to the
internal bandgap voltage.
Note 8: The current comparator output current varies linearly with
temperature.
Note 9: The PWRGD and OVP comparators incorporate 10mV of
hysteresis.
Note 10: The driver disable time-out is proportional to the SYNC period
within the frequency synchronization range.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
AUX
V
AUX
Auxiliary Supply Voltage C
VAUX
= 0.1µF, I
LOAD
= 0mA to 10mA, V
DD
= 7V to 12.6V ● 3.135 3.320 3.465 V
Current Limit Amplifier
I
ISNSGND
I
SNSGND
Input Current V
ISNSGND
= 0V ● 0.05 1 µA
I
ISNS
I
SNS
Input Current V
ISNS
= 0V ● 0.05 1 µA
V
ILIMTH
Current Limit Threshold V
ICOMP
= 2.5V, V
ISNSGND
= 0V –27.0 –25 –23.0 mV
(V
ISNS
– V
ISNSGND
) ● –27.5 –25 –22.5 mV
I
ICOMP
I
COMP
Source Current V
ISNSGND
= 0V, V
ISNS
= –0.3V, V
ICOMP
= 2.5V (Note 8) –280 –200 –120 µA
● –370 –200 –80 µA
I
COMP
Sink Current V
ISNSGND
= 0V, V
ISNS
= 0.3V, V
ICOMP
= 2.5V (Note 8) 120 200 280 µA
● 80 200 370 µA
g
mILIM
Current Limit Amplifier V
ISNSGND
= 0V, V
ICOMP
= 2.5V, I
ICOMP
= ±10µA ● 2.2 3.5 5 millimho
Transconductance
G
ICOMP
Current Limit Amplifier V
ICOMP
= 2.5V, No Load ● 48 60 dB
Open-Loop DC Gain
PWRGD and OVP Comparators
V
PWRGD
Percent Below V
FB
V
FB
↓, MARGIN = Open (Note 9) ● –9 –6 –3 %
I
PWRGD
Power Good Sink Current V
FB
= 2V ● 10 µA
V
FB
= 0V ● 10 mA
V
OL
Power Good Output Low Voltage I
PWRGD
= 3mA, V
FB
= 0V ● 0.4 V
V
OVPREF
OVPIN Threshold V
FB
= V
ISNS
= V
ISNSGND
= 0V, OVPIN ↑ (Note 9) ● 1.18 1.233 1.28 V
I
OVPIN
OVPIN Input Bias Current V
OVPIN
= 1.233V ● 0.1 1 µA
t
PWRGD
Power Good Response Time V
FB
↑ ● 125 ms
Power Bad Response Time V
FB
↓ ● 0.5 1 2.5 ms
t
OVP
Overvoltage Response Time V
OVPIN
↑, C
OPTODRV
= 0.1µF ● 520 µs
SYNC and Drivers
V
PT
SYNC Input Positive Threshold ● 1 1.6 2.2 V
V
NT
SYNC Input Negative Threshold ● –2.2 –1.6 –1 V
I
SYNC
SYNC Input Current V
SYNC
= ±10V ● 150 µA
f
SYNC
SYNC Frequency Range C
FG
= C
CG
= 1000pF, V
SYNC
= ±5V ● 50 400 kHz
t
d
SYNC Input to Driver Output Delay C
FG
= C
CG
= 1000pF, f
SYNC
= 100kHz, V
SYNC
= ±5V ● 40 90 ns
t
SYNC
Minimum SYNC Pulse Width f
SYNC
= 100kHz, V
SYNC
= ±10V (Note 6) ● 75 ns
t
r
, t
f
Driver Rise and Fall Time C
FG
= C
CG
= 1000pF, f
SYNC
= 100kHz, V
SYNC
= ±5V, ● 10 40 ns
10% to 90%
t
DDIS
Driver Disable Time-Out C
FG
= C
CG
= 1000pF, f
SYNC
= 100kHz, V
SYNC
= ±5V
Measured from CG ↑ (Note 10) ● 10 15 20 µs