LT1317/LT1317B
Micropower, 600kHz PWM
DC/DC Converters
FEATURES
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DESCRIPTION
The LT
®
1317/LT1317B are micropower, fixed frequency
step-up DC/DC converters that operate over a wide input
voltage range of 1.5V to 12V. The LT1317 features auto-
matic shifting to power saving Burst Mode
TM
operation at
light loads. High efficiency is maintained over a broad
300µA to 200mA load range. Peak switch current during
Burst Mode operation is kept below 250mA for most
operating conditions which results in low output ripple
voltage, even at high input voltages. The LT1317B does
not shift into Burst Mode operation at light loads, eliminat-
ing low frequency output ripple at the expense of light load
efficiency.
The LT1317/LT1317B contain an internal low-battery de-
tector with a 200mV reference that stays alive when the
device goes into shutdown.
No-load quiescent current of the LT1317 is 100µA and
shuts down to 30µA. The internal NPN power switch
handles a 500mA current with a voltage drop of just
300mV.
The LT1317/LT1317B are available in MS8 and SO-8
packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a trademark of Linear Technology Corporation.
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100µA Quiescent Current
Operates with V
IN
as Low as 1.5V
600kHz Fixed Frequency Operation
Starts into Full Load
Low-Battery Detector Active in Shutdown
Automatic Burst Mode Operation at
Light Load (LT1317)
Continuous Switching at Light Loads (LT1317B)
Low V
CESAT
Switch: 300mV at 500mA
Pin for Pin Compatible with the LT1307/LT1307B
APPLICATIONS
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Cellular Telephones
Cordless Telephones
Pagers
GPS Receivers
Battery Backup
Portable Electronic Equipment
Glucose Meters
Diagnostic Medical Instrumentation
TYPICAL APPLICATION
L1
10µH
2-Cell to 3.3V Converter Efficiency
D1
90
2.2V
IN
3V
IN
+
C1
47µF
V
IN
LBI
LT1317
SHDN
V
C
R
C
33k
C
C
3.3nF
SW
FB
LBO
GND
R1
1M
1%
R2*
604k
1%
3.3V
200mA
80
EFFICIENCY (%)
2
CELLS
SHUTDOWN
70
+
C2
47µF
60
50
1317 F01
D1: MBR0520
L1: SUMIDA CD43-100
* FOR 5V OUTPUT, R2 = 332k, 1%
40
0.3
1
Figure 1. 2-Cell to 3.3V Boost Converter
U
U
U
1.65V
IN
10
100
LOAD CURRENT (mA)
1000
1317 TA01
1
LT1317/LT1317B
ABSOLUTE
AXI U
RATI GS
V
IN
, LBO Voltage ..................................................... 12V
SW Voltage ............................................... – 0.4V to 30V
FB Voltage .................................................... V
IN
+ 0.3V
V
C
Voltage ................................................................ 2V
LBI Voltage ............................................ 0V
≤
V
LBI
≤
1V
SHDN Voltage ............................................................ 6V
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
C
FB
SHDN
GND
1
2
3
4
8
7
6
5
LBO
LBI
V
IN
SW
ORDER PART
NUMBER
LT1317CMS8
LT1317BCMS8
V
C
1
FB 2
SHDN 3
GND 4
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 160°C/W
MS8 PART MARKING
LTHA
LTHB
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
Commercial Grade
SYMBOL
I
Q
PARAMETER
Quiescent Current
V
IN
= 2V, V
SHDN
= 2V, T
A
= 25°C, unless otherwise noted.
CONDITIONS
Not Switching, V
SHDN
= 2V (LT1317)
V
SHDN
= 0V (LT1317/LT1317B)
V
SHDN
= 2V, Switching (LT1317B)
V
SHDN
= 2V, Switching (LT1317B)
q
q
q
q
V
FB
I
B
g
m
A
V
Feedback Voltage
FB Pin Bias Current (Note 2)
Input Voltage Range
Error Amp Transconductance
Error Amp Voltage Gain
Maximum Duty Cycle
Switch Current Limit (Note 3)
Burst Mode Operation Switch Current Limit
V
IN
= 2.5V, Duty Cycle = 30%
V
IN
= 2.5V, Duty Cycle = 30%
Duty Cycle = 30% (LT1317)
q
q
q
q
q
∆I
= 5µA
f
OSC
Switching Frequency
2
U
U
W
W W
U
W
(Note 1)
Junction Temperature .......................................... 125°C
Operating Temperature Range
Commercial ........................................... 0°C to 70°C
Industrial ............................................ – 40°C to 85°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................ 300°C
TOP VIEW
8
7
6
5
LBO
LBI
V
IN
SW
ORDER PART
NUMBER
LT1317CS8
LT1317BCS8
LT1317IS8
LT1317BIS8
S8 PART MARKING
1317
1317B
1317I
1317BI
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 125°C,
θ
JA
= 120°C/W
MIN
TYP
100
25
4.8
MAX
160
40
6.5
7.5
1.26
1.26
60
12
240
UNITS
µA
µA
mA
mA
V
V
nA
V
µmhos
V/V
%
1.22
1.20
1.5
70
80
710
660
520
1.24
1.24
12
140
700
85
800
275
620
q
1300
1350
720
mA
mA
mA
kHz
LT1317/LT1317B
ELECTRICAL CHARACTERISTICS
Commercial Grade
SYMBOL
PARAMETER
Shutdown Pin Current
LBI Threshold Voltage
q
V
IN
= 2V, V
SHDN
= 2V, T
A
= 25°C unless otherwise noted.
CONDITIONS
V
SHDN
= V
IN
V
SHDN
= 0V
q
q
MIN
TYP
0.015
– 2.3
MAX
0.06
–6
210
220
0.25
0.1
40
3
350
400
0.15
6
0.4
UNITS
µA
µA
mV
mV
V
µA
nA
V/V
µA
mV
mV
%/V
V
V
190
180
200
200
0.15
0.02
5
2000
0.01
300
LBO Output Low
LBO Leakage Current
LBI Input Bias Current (Note 4)
Low-Battery Detector Gain
Switch Leakage Current
Switch V
CE
Sat
Reference Line Regulation
SHDN Input Voltage High
SHDN Input Voltage Low
I
SINK
= 10µA
V
LBI
= 250mV, V
LBO
= 5V
V
LBI
= 150mV
1MΩ Load
V
SW
= 5V
I
SW
= 500mA
q
q
q
q
q
1.8V
≤
V
IN
≤
12V
q
q
q
0.08
1.4
Industrial Grade
SYMBOL
I
Q
V
IN
= 2V, V
SHDN
= 2V, – 40°C
≤
T
A
≤
85°C unless otherwise noted.
CONDITIONS
Not Switching, V
SHDN
= 2V (LT1317)
V
SHDN
= 0V (LT1317/LT1317B)
V
SHDN
= 2V, Switching (LT1317B)
q
q
q
q
q
q
PARAMETER
Quiescent Current
MIN
TYP
MAX
160
40
7.5
UNITS
µA
µA
mA
V
nA
V
µmhos
%
mA
kHz
µA
µA
mV
V
µA
nA
µA
mV
%/V
V
V
V
FB
I
B
g
m
Feedback Voltage
FB Pin Bias Current (Note 2)
Input Voltage Range
Error Amp Transconductance
Maximum Duty Cycle
Switch Current Limit (Note 3)
V
IN
= 2.5V, Duty Cycle = 30%
V
SHDN
= V
IN
V
SHDN
= 0V
I
SINK
= 10µA
V
LBI
= 250mV, V
LBO
= 5V
V
LBI
= 150mV
V
SW
= 5V
I
SW
= 500mA
1.8V
≤
V
IN
≤
12V
∆I
= 5µA
1.20
1.7
70
80
550
500
140
1.26
80
12
240
1350
750
0.1
–7
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
f
OSC
Switching Frequency
Shutdown Pin Current
LBI Threshold Voltage
LBO Output Low
LBO Leakage Current
LBI Input Bias Current (Note 4)
Switch Leakage Current
Switch V
CE
Sat
Reference Line Regulation
SHDN Input Voltage High
SHDN Input Voltage Low
180
220
0.25
0.1
60
3
400
0.15
1.4
6
0.4
The
q
denotes specifications which apply over the full operating
temperature range.
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
Bias current flows into FB pin.
Note 3:
Switch current limit guaranteed by design and/or correlation to
static tests. Duty cycle affects current limit due to ramp generator.
Note 4:
Bias current flows out of LBI pin.
3
LT1317/LT1317B
TYPICAL PERFOR A CE CHARACTERISTICS
Oscillator Frequency
700
OSCILLATOR FREQUENCY (kHz)
–40°C
25°C
600
SWITCH CURRENT (mA)
650
85°C
600
SWITCH CURRENT (mA)
550
500
0
2
4
6
8
INPUT VOLTAGE
Switch Current Limit
1200
6
5
4
3
2
1
1000
SWITCH VOLTAGE (V
CESAT
) (mV)
LBI INPUT BIAS CURRENT (nA)
SWITCH CURRENT (mA)
TYPICAL
800
600
MINIMUM (25°C)
400
200
0
20
40
60
DUTY CYCLE (%)
80
100
1317 TPC04
Feedback Voltage
1.25
203
202
LBI REFERENCE VOLTAGE (mV)
QUIESCENT CURRENT (µA)
1.24
FEEDBACK VOLTAGE (V)
1.23
1.22
1.21
1.20
–50
–25
0
25
50
TEMPERATURE (°C)
4
U W
10
1317 TPC01
Burst Mode Current Limit (LT1317)
800
V
IN
= 2V
L = 10µH
1000
Switch Current Limit,
Duty Cycle = 30%
900
800
400
700
200
600
12
0
0
20
40
60
DUTY CYCLE (%)
80
100
1317 TPC02
500
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
1317 TPC03
LBI Input Bias Current
700
600
500
400
300
200
100
0
–25
0
25
50
TEMPERATURE (°C)
75
100
Switch Voltage Drop (V
CESAT
)
85°C
25°C
–40°C
0
–50
0
0.2
0.4
0.6
0.8
SWITCH CURRENT (A)
1
1317 TPC06
1317 TPC05
LBI Reference Voltage
110
100
90
80
70
60
50
40
Quiescent Current, SHDN = 2V
201
200
199
198
197
196
75
100
195
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
30
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
1317 TPC07
1317 TPC08
1317 TPC09
LT1317/LT1317B
TYPICAL PERFOR A CE CHARACTERISTICS
Quiescent Current, SHDN = 0V
26
25
QUIESCENT CURRENT (µA)
FB PIN BIAS CURRENT (nA)
24
23
22
21
20
–50
28
24
20
16
12
8
4
SHDN PIN CURRENT (µA)
–25
0
25
50
TEMPERATURE (°C)
5V Output Efficiency, Circuit of
Figure 1 (LT1317)
90
80
EFFICIENCY (%)
EFFICIENCY (%)
EFFICIENCY (%)
70
60
V
IN
= 1.65V
V
IN
= 2.2V
50
0.3
1
V
IN
= 3V
10
100
LOAD CURRENT (mA)
Transient Response (LT1317)
V
OUT
100mV/DIV
AC COUPLED
I
L
200mA/DIV
I
LOAD
165mA
5mA
V
IN
= 2V
1ms/DIV
V
OUT
= 3.3V
CIRCUIT OF FIGURE 1
1317 TPC16
U W
75
1317 TPC10
1317 TPC13
FB Pin Bias Current
40
36
32
1
2
SHDN Pin Current
0
–1
–2
100
0
–50
–3
–25
0
25
50
TEMPERATURE (°C)
75
100
0
1
4
3
SHDN PIN VOLTAGE (V)
2
5
6
1317 TPC12
1317 TPC11
2-Cell to 3.3V Converter
Efficiency (LT1317B)
90
90
2-Cell to 5V Converter Efficiency
(LT1317B)
80
80
70
70
60
V
IN
= 1.65V
50
V
IN
= 2.2V
V
IN
= 3V
40
60
V
IN
= 1.65V
50
V
IN
= 2.2V
V
IN
= 3V
40
1000
1
10
100
LOAD CURRENT (mA)
1000
1317 TPC14
1
10
100
LOAD CURRENT (mA)
1000
1317 TPC15
Transient Response (LT1317B)
V
OUT
100mV/DIV
AC COUPLED
I
L
200mA/DIV
I
LOAD
165mA
5mA
V
IN
= 2V
1ms/DIV
V
OUT
= 3.3V
CIRCUIT OF FIGURE 1
WITH LT1317B
1317 TPC17
Burst Mode Operation (LT1317)
V
OUT
50mV/DIV
AC COUPLED
I
L
200mA/DIV
V
SW
5V/DIV
V
IN
= 2V
20µs/DIV
V
OUT
= 3.3V
I
LOAD
= 30mA
CIRCUIT OF FIGURE 1
1317 TPC18
5
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