LTC1538-AUX Linear Technology, LTC1538-AUX Datasheet - Page 4

• Manufacturer Part Number: LTC1538-AUX
• Description: Dual High Efficiency/ Low Noise/ Synchronous Step-Down Switching Regulators
• Manufacturer: Linear Technology

LTC1538-AUX/LTC1539
SYMBOL
Low-Battery Comparator
V
I
V
I
V
Auxiliary Regulator/Comparator
I
I
I
V
V
V
V
The
temperature range.
Note 1: T
dissipation P
Note 2: The LTC1538-AUX and LTC1539 are tested in a feedback loop
which servos V
(V
4
ELECTRICAL CHARACTERISTICS
LLBO
INLB1
AUXDR
INAUXFB
INAUXON
SATLBO
THLB1
HYSLBO
THAUXON
SATAUXDR
AUXFB
THAUXDR
ITH1,2
LTC1538CG-AUX: T
LTC1539CGW: T
denotes specifications which apply over the full operating
= 1.19V).
J
is calculated from the ambient temperature T
D
according to the following formulas:
OSENSE1,2
PARAMETER
LBO Saturation Voltage
LBO Leakage
LBI Trip Voltage
LBI Input Current
LBO Hysteresis
AUXDR Current
AUXFB Input Current
AUXON Input Current
AUXON Trip Voltage
AUXDR Saturation Voltage
AUXFB Voltage
AUXFB Divider Disconnect Voltage
Max Current Sinking Capability
Control Current
Leakage when OFF
J
= T
J
= T
A
to the balance point for the error amplifier
+ (P
A
+ (P
D
)(85 C/W)
D
)(95 C/W)
A
and power
CONDITIONS
I
V
High to Low Transition on LBO
V
V
V
V
V
V
V
V
I
V
V
V
LBO
AUXDR
LBO
LBI
EXTVCC
AUXDR
AUXDR
AUXDR
AUXFB
AUXON
AUXDR
AUXON
AUXON
AUXON
= 1.6mA, V
= 1.19V
= 12V, V
= 1.6mA, V
= 1.19V, V
= 4V, V
= 5V, V
= 24V, V
= 5V
= 4V, V
= 5V, 11V < V
= 5V, 3V < V
= 5V (Note 5); Ramping Negative
T
= 0V
A
= 25 C, V
LBI
AUXFB
AUXFB
AUXFB
LBI
AUXFB
= 1.4V
AUXON
AUXFB
= 1.1V
Note 3: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications Information.
Note 4: Oscillator frequency is tested by measuring the C
discharge current (I
Note 5: The auxiliary regulator is tested in a feedback loop which servos
V
V
Information section.
AUXDR
= 1.0V, V
= 1.5V, V
= 1V
AUXFB
AUXDR
AUXDR
IN
= 1.5V, V
f
OSC
= 5V
= 1V, V
= 15V, V
< 7V
to the balance point for the error amplifier. For applications with
> 9.5V, V
< 24V (Note 5)
(kHz) = 8.4(10
AUXON
AUXON
AUXON
AUXON
RUN/SS1,2
= 5V
= 5V
AUXFB
= 0V
= 5V
OSC
8
) and applying the formula:
)[C
uses an internal resistive divider. See Applications
= 5V unless otherwise noted.
OSC
(pF) + 11]
MIN
1.16
11.5
1.0
7.5
10
1.14
-1
(1/I
CHG
1.19
12.00
TYP
0.01
1.19
0.01
0.01
0.01
0.6
0.4
8.5
20
15
+ 1/I
1.19
1
1
DISC
OSC
)
MAX
–1
1.22
12.5
charge and
1.4
0.8
9.5
50
1.24
1
1
5
1
1
1
UNITS
mV
mA
nA
V
A
V
A
A
A
A
V
V
V
V
V