Voltage .......................................................5V
BIAS, PG, BD Voltage ................................................25V
Operating Junction Temperature Range (Note 2)
LT1938E ............................................. –40°C to 125°C
LT1938I .............................................. –40°C to 125°C
Storage Temperature Range................... –65°C to 150°C
(Note 1)
PIN CONFIgURATION
TOP VIEW
BD
BOOST
SW
V
IN
RUN/SS
1
2
3
4
5
11
10 RT
9 V
C
8 FB
7 BIAS
6 PG
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 45°C/W,
θ
JC
= 10°C/W
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LT1938EDD#PBF
LT1938IDD#PBF
TAPE AND REEL
LT1938EDD#TRPBF
LT1938IDD#TRPBF
PART MARKING*
LDFT
LDFT
PACKAGE DESCRIPTION
10-Lead (3mm × 3mm) Plastic DFN
10-Lead (3mm × 3mm) Plastic DFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
ELECTRICAL ChARACTERISTICS
PARAMETER
Minimum Input Voltage
Quiescent Current from V
IN
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 10V, V
RUN/SS
= 10V, V
BOOST
= 15V, V
BIAS
= 3.3V unless otherwise
noted. (Note 2)
CONDITIONS
●
MIN
TYP
3
0.01
0.4
1.2
0.01
MAX
3.6
0.5
0.8
2.0
0.5
1.5
0.1
3
1.28
1.29
100
0.02
UNITS
V
µA
mA
mA
µA
mA
mA
V
V
V
nA
%/V
V
RUN/SS
= 0.2V
V
BIAS
= 3V, Not Switching
V
BIAS
= 0, Not Switching
●
Quiescent Current from BIAS
V
RUN/SS
= 0.2V
V
BIAS
= 3V, Not Switching
V
BIAS
= 0, Not Switching
●
0.85
0
2.7
1.25
1.24
1.265
1.265
30
0.002
Minimum Bias Voltage
Feedback Voltage
●
FB Pin Bias Current (Note 3)
FB Voltage Line Regulation
4V < V
IN
< 25V
●
1938fa
2
LT1938
ELECTRICAL ChARACTERISTICS
PARAMETER
Error Amp g
m
Error Amp Gain
V
C
Source Current
V
C
Sink Current
V
C
Pin to Switch Current Gain
V
C
Clamp Voltage
Switching Frequency
R
T
= 8.66k
R
T
= 29.4k
R
T
= 187k
●
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 10V, V
RUN/SS
= 10V V
BOOST
= 15V, V
BIAS
= 3.3V unless otherwise
noted. (Note 2)
CONDITIONS
MIN
TYP
330
1000
75
100
3.5
2
2.7
1.25
250
3.1
3.0
1.4
300
100
3.6
360
0.02
●
MAX
UNITS
µMho
µA
µA
A/V
V
3.3
1.55
350
150
4.0
2
2.1
30
10
0.2
MHz
MHz
kHz
nS
A
mV
µA
V
mA
µA
V
V
mV
mV
Minimum Switch Off-Time
Switch Current Limit
Switch V
CESAT
Boost Schottky Reverse Leakage
Minimum Boost Voltage (Note 4)
BOOST Pin Current
RUN/SS Pin Current
RUN/SS Input Voltage High
RUN/SS Input Voltage Low
PG Threshold Offset from Feedback Voltage
PG Hysteresis
PG Leakage
PG Sink Current
V
PG
= 5V
V
PG
= 0.4V
V
FB
Rising
I
SW
= 1A
V
RUN/SS
= 2.5V
Duty Cycle = 5%
I
SW
= 2A
V
SW
= 10V, V
BIAS
= 0V
1.6
18
5
2.5
100
10
0.1
1
µA
µA
●
100
300
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 LT1938E is guaranteed to meet performance specifications
from 0°C to 125°C. Specifications over the –40°C to 125°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. The LT1938I specifications are
guaranteed over the –40°C to 125°C temperature range.
Note 3:
Bias current measured in regulation. Bias current flows into the FB
pin.
Note 4:
This is the minimum voltage across the boost capacitor needed to
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