LT1317/LT1317B
Micropower, 600kHz PWM
DC/DC Converters
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DESCRIPTION
FEATURES
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100µA Quiescent Current
Operates with VIN 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 VCESAT Switch: 300mV at 500mA
Pin for Pin Compatible with the LT1307/LT1307B
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APPLICATIONS
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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 automatic shifting to power saving Burst ModeTM 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, eliminating low frequency output ripple at the expense of light load
efficiency.
The LT1317/LT1317B contain an internal low-battery detector with a 200mV reference that stays alive when the
device goes into shutdown.
Cellular Telephones
Cordless Telephones
Pagers
GPS Receivers
Battery Backup
Portable Electronic Equipment
Glucose Meters
Diagnostic Medical Instrumentation
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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TYPICAL APPLICATION
2-Cell to 3.3V Converter Efficiency
L1
10µH
90
2.2VIN
C1
47µF
VIN
LBI
SW
FB
LT1317
2
CELLS
SHUTDOWN
SHDN
VC
RC
33k
CC
3.3nF
LBO
GND
R1
1M
1%
80
3.3V
200mA
+
R2*
604k
1%
D1: MBR0520
L1: SUMIDA CD43-100
* FOR 5V OUTPUT, R2 = 332k, 1%
Figure 1. 2-Cell to 3.3V Boost Converter
C2
47µF
EFFICIENCY (%)
+
D1
3VIN
1.65VIN
70
60
50
1317 F01
40
0.3
1
10
100
LOAD CURRENT (mA)
1000
1317 TA01
1
LT1317/LT1317B
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ABSOLUTE
RATI GS
(Note 1)
VIN, LBO Voltage ..................................................... 12V
SW Voltage ............................................... – 0.4V to 30V
FB Voltage .................................................... VIN + 0.3V
VC Voltage ................................................................ 2V
LBI Voltage ............................................ 0V ≤ VLBI ≤ 1V
SHDN Voltage ............................................................ 6V
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
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PACKAGE/ORDER I FOR ATIO
ORDER PART
NUMBER
TOP VIEW
VC
FB
SHDN
GND
1
2
3
4
8
7
6
5
LBO
LBI
VIN
SW
LT1317CMS8
LT1317BCMS8
MS8 PACKAGE
8-LEAD PLASTIC MSOP
TJMAX = 125°C, θJA = 160°C/W
MS8 PART MARKING
ORDER PART
NUMBER
TOP VIEW
VC 1
8
LBO
FB 2
7
LBI
SHDN 3
6
VIN
GND 4
5
SW
LT1317CS8
LT1317BCS8
LT1317IS8
LT1317BIS8
S8 PACKAGE
8-LEAD PLASTIC SO
S8 PART MARKING
TJMAX = 125°C, θJA = 120°C/W
1317
1317B
1317I
1317BI
LTHA
LTHB
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
Commercial Grade
VIN = 2V, VSHDN = 2V, TA = 25°C, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
IQ
Quiescent Current
Not Switching, VSHDN = 2V (LT1317)
VSHDN = 0V (LT1317/LT1317B)
VSHDN = 2V, Switching (LT1317B)
VSHDN = 2V, Switching (LT1317B)
VFB
Feedback Voltage
MIN
●
●
µA
µA
mA
mA
1.22
1.20
1.24
1.24
1.26
1.26
V
V
12
60
nA
12
V
240
µmhos
●
Input Voltage Range
●
1.5
●
70
700
V/V
●
80
85
%
710
660
800
●
Error Amp Transconductance
AV
Error Amp Voltage Gain
∆I = 5µA
Maximum Duty Cycle
Switch Current Limit (Note 3)
Burst Mode Operation Switch Current Limit
2
UNITS
160
40
6.5
7.5
FB Pin Bias Current (Note 2)
gm
fOSC
MAX
100
25
4.8
●
●
IB
TYP
Switching Frequency
VIN = 2.5V, Duty Cycle = 30%
VIN = 2.5V, Duty Cycle = 30%
Duty Cycle = 30% (LT1317)
140
1300
1350
275
●
520
620
mA
mA
mA
720
kHz
LT1317/LT1317B
ELECTRICAL CHARACTERISTICS
Commercial Grade
SYMBOL
VIN = 2V, VSHDN = 2V, TA = 25°C unless otherwise noted.
PARAMETER
CONDITIONS
Shutdown Pin Current
VSHDN = VIN
VSHDN = 0V
MIN
●
●
LBI Threshold Voltage
●
190
180
TYP
MAX
UNITS
0.015
– 2.3
0.06
–6
µA
µA
200
200
210
220
mV
mV
LBO Output Low
ISINK = 10µA
●
0.15
0.25
V
LBO Leakage Current
VLBI = 250mV, VLBO = 5V
●
0.02
0.1
µA
LBI Input Bias Current (Note 4)
VLBI = 150mV
●
5
40
nA
Low-Battery Detector Gain
1MΩ Load
Switch Leakage Current
VSW = 5V
Switch VCE Sat
ISW = 500mA
2000
●
3
µA
300
350
400
mV
mV
0.08
0.15
%/V
●
Reference Line Regulation
1.8V ≤ VIN ≤ 12V
●
SHDN Input Voltage High
●
SHDN Input Voltage Low
●
Industrial Grade
1.4
PARAMETER
CONDITIONS
IQ
Quiescent Current
Not Switching, VSHDN = 2V (LT1317)
VSHDN = 0V (LT1317/LT1317B)
VSHDN = 2V, Switching (LT1317B)
VFB
Feedback Voltage
●
IB
FB Pin Bias Current (Note 2)
●
Input Voltage Range
●
1.7
●
70
Error Amp Transconductance
∆I = 5µA
Maximum Duty Cycle
Switch Current Limit (Note 3)
fOSC
6
V
0.4
V
VIN = 2V, VSHDN = 2V, – 40°C ≤ TA ≤ 85°C unless otherwise noted.
SYMBOL
gm
V/V
0.01
VIN = 2.5V, Duty Cycle = 30%
Switching Frequency
Shutdown Pin Current
VSHDN = VIN
VSHDN = 0V
MIN
●
●
●
1.20
140
MAX
UNITS
160
40
7.5
µA
µA
mA
1.26
V
80
nA
12
V
240
µmhos
●
80
●
550
1350
mA
●
500
750
kHz
0.1
–7
µA
µA
220
mV
●
●
LBI Threshold Voltage
TYP
●
180
%
LBO Output Low
ISINK = 10µA
●
0.25
V
LBO Leakage Current
VLBI = 250mV, VLBO = 5V
●
0.1
µA
LBI Input Bias Current (Note 4)
VLBI = 150mV
●
60
nA
Switch Leakage Current
VSW = 5V
●
3
µA
Switch VCE Sat
ISW = 500mA
●
400
mV
Reference Line Regulation
1.8V ≤ VIN ≤ 12V
●
0.15
%/V
SHDN Input Voltage High
●
SHDN Input Voltage Low
●
The ● 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.
1.4
6
V
0.4
V
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.
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LT1317/LT1317B
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TYPICAL PERFOR A CE CHARACTERISTICS
Oscillator Frequency
1000
800
VIN = 2V
L = 10µH
25°C
85°C
600
550
0
2
4
6
8
INPUT VOLTAGE
10
900
SWITCH CURRENT (mA)
–40°C
650
SWITCH CURRENT (mA)
OSCILLATOR FREQUENCY (kHz)
700
500
600
400
200
0
20
40
60
DUTY CYCLE (%)
800
600
MINIMUM (25°C)
400
200
20
40
60
DUTY CYCLE (%)
80
5
4
3
2
1
Feedback Voltage
0
25
50
TEMPERATURE (°C)
75
0
25
50
TEMPERATURE (°C)
–40°C
300
200
100
0
75
100
1317 TPC07
0.2
0.4
0.6
0.8
SWITCH CURRENT (A)
Quiescent Current, SHDN = 2V
110
202
100
201
200
199
198
197
195
–50
1
1317 TPC06
203
90
80
70
60
50
40
196
–25
25°C
400
100
QUIESCENT CURRENT (µA)
LBI REFERENCE VOLTAGE (mV)
1.21
1.20
–50
500
LBI Reference Voltage
1.22
85°C
600
1317 TPC05
1.25
100
0
–25
1317 TPC04
1.23
75
700
0
–50
100
1.24
0
25
50
TEMPERATURE (°C)
Switch Voltage Drop (VCESAT)
SWITCH VOLTAGE (VCESAT) (mV)
LBI INPUT BIAS CURRENT (nA)
TYPICAL
–25
1317 TPC03
6
1000
SWITCH CURRENT (mA)
100
LBI Input Bias Current
1200
FEEDBACK VOLTAGE (V)
80
1317 TPC02
Switch Current Limit
0
700
500
–50
0
12
800
600
1317 TPC01
4
Switch Current Limit,
Duty Cycle = 30%
Burst Mode Current Limit (LT1317)
–25
0
25
50
TEMPERATURE (°C)
75
100
1317 TPC08
30
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
1317 TPC09
LT1317/LT1317B
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TYPICAL PERFOR A CE CHARACTERISTICS
Quiescent Current, SHDN = 0V
SHDN Pin Current
FB Pin Bias Current
26
40
2
36
24
23
22
21
32
SHDN PIN CURRENT (µA)
FB PIN BIAS CURRENT (nA)
QUIESCENT CURRENT (µA)
25
28
24
20
16
12
1
0
–1
–2
8
4
20
–50
–25
0
25
50
TEMPERATURE (°C)
75
0
–50
100
–3
–25
0
25
50
TEMPERATURE (°C)
1317 TPC10
0
100
80
80
80
EFFICIENCY (%)
90
EFFICIENCY (%)
90
70
60
VIN = 1.65V
50
VIN = 3V
1
10
100
LOAD CURRENT (mA)
60
VIN = 1.65V
50
VIN = 2.2V
VIN = 2.2V
VIN = 3V
VIN = 3V
40
40
0.3
70
VIN = 1.65V
50
VIN = 2.2V
1000
1
10
100
LOAD CURRENT (mA)
1000
1
Transient Response (LT1317)
Burst Mode Operation (LT1317)
VOUT
100mV/DIV
AC COUPLED
VOUT
100mV/DIV
AC COUPLED
VOUT
50mV/DIV
AC COUPLED
IL
200mA/DIV
IL
200mA/DIV
IL
200mA/DIV
ILOAD 165mA
5mA
ILOAD 165mA
5mA
VSW
5V/DIV
VIN = 2V
1ms/DIV
VOUT = 3.3V
CIRCUIT OF FIGURE 1
WITH LT1317B
1317 TPC17
1000
1317 TPC15
Transient Response (LT1317B)
1317 TPC16
10
100
LOAD CURRENT (mA)
1317 TPC14
1317 TPC13
VIN = 2V
1ms/DIV
VOUT = 3.3V
CIRCUIT OF FIGURE 1
6
5
2-Cell to 5V Converter Efficiency
(LT1317B)
90
60
2
4
3
SHDN PIN VOLTAGE (V)
1317 TPC12
2-Cell to 3.3V Converter
Efficiency (LT1317B)
70
1
1317 TPC11
5V Output Efficiency, Circuit of
Figure 1 (LT1317)
EFFICIENCY (%)
75
VIN = 2V
20µs/DIV
VOUT = 3.3V
ILOAD = 30mA
CIRCUIT OF FIGURE 1
1317 TPC18
5
LT1317/LT1317B
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TYPICAL PERFOR A CE CHARACTERISTICS
Load Regulation (LT1317)
Load Regulation (LT1317)
VOUT
50mV/DIV
DC COUPLED
OFFSET
ADDED
Load Regulation (LT1317)
VOUT
50mV/DIV
DC COUPLED
OFFSET
ADDED
VOUT
50mV/DIV
DC COUPLED
OFFSET
ADDED
VIN = 1.5V
VOUT = 5V
ILOAD 25mA/DIV
VIN = 2V
VOUT = 5V
1317 TPC19
Load Regulation (LT1317)
ILOAD 25mA/DIV
Load Regulation (LT1317)
ILOAD 25mA/DIV
1317 TPC22
ILOAD 50mA/DIV
1317 TPC21
Load Regulation (LT1317)
VOUT
50mV/DIV
DC COUPLED
OFFSET
ADDED
VOUT
50mV/DIV
DC COUPLED
OFFSET
ADDED
VIN = 1.5V
VOUT = 3.3V
VIN = 2.5V
VOUT = 5V
1317 TPC20
VOUT
50mV/DIV
DC COUPLED
OFFSET
ADDED
VIN = 2V
VOUT = 3.3V
ILOAD 50mA/DIV
1317 TPC23
VIN = 2.5V
VOUT = 3.3V
ILOAD 50mA/DIV
1317 TPC24
Note: For load regulation pictures, double lines are due to
output capacitor ESR.
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PIN FUNCTIONS
VC (Pin 1): Compensation Pin for Error Amplifier. Connect a series RC network from this pin to ground. Typical
values for compensation are a 33k/3.3nF combination. A
100pF capacitor from the VC pin to ground is optional and
improves noise immunity. Minimize trace area at VC.
FB (Pin 2): Feedback Pin. Reference voltage is 1.24V.
Connect resistor divider tap here. Minimize trace area at
FB. Set VOUT according to: VOUT = 1.24V(1 + R1/R2).
SHDN (Pin 3): Shutdown. Pull this pin low for shutdown
mode (only the low-battery detector remains active).
Leave this pin floating or tie to a voltage between 1.4V and
6V to enable the device. SHDN pin is logic level and need
only meet the logic specification (1.4V for high, 0.4V for
low).
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GND (Pin 4): Ground. Connect directly to local ground
plane.
SW (Pin 5): Switch Pin. Connect inductor/diode here.
Minimize trace area at this pin to keep EMI down.
VIN (Pin 6): Supply Pin. Must be bypassed close to the
pin.
LBI (Pin 7): Low-Battery Detector Input. 200mV reference. Voltage on LBI must stay between ground and
700mV. Low-battery detector remains active in shutdown
mode.
LBO (Pin 8): Low-Battery Detector Output. Open collector, can sink 10µA. A 1MΩ pull-up is recommended.
LT1317/LT1317B
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BLOCK DIAGRAM
LBI
1.24V
REFERENCE
+
gm
FB
2
+
7
VC
LBO
8
1
–
ERROR
AMPLIFIER
+
–
200mV
A4
ENABLE
SHDN
VOUT
BIAS
R1
(EXTERNAL)
–
SHUTDOWN
3
A1
COMPARATOR
SW
FB
5
–
R2
(EXTERNAL)
RAMP
GENERATOR
+
Σ
+
+
FF
Q3
Q
R
A2
COMPARATOR
DRIVER
S
+
A=2
600kHz
OSCILLATOR
0.08Ω
–
4
GND
1317 BD
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APPLICATIONS INFORMATION
OPERATION
The LT1317 combines a current mode, fixed frequency
PWM architecture with Burst Mode micropower operation
to maintain high efficiency at light loads. Operation can
best be understood by referring to the Block Diagram.
The error amplifier compares voltage at the FB pin with the
internal 1.24V bandgap reference and generates an error
signal VC. When VC decreases below the bias voltage on
hysteretic comparator A1, A1’s output goes low, turning
off all circuitry except the 1.24V reference, error amplifier
and low-battery detector. Total current consumption in
this state is 100µA. As output loading causes the FB
voltage to decrease, VC increases causing A1’s output to
go high, in turn enabling the rest of the IC. Switch current
is limited to approximately 250mA initially after A1’s
output goes high. If the load is light, the output voltage
(and FB voltage) will increase until A1’s output goes low,
turning off the rest of the LT1317. Low frequency ripple
voltage appears at the output. The ripple frequency is
dependent on load current and output capacitance. This
Burst Mode operation keeps the output regulated and
reduces average current into the IC, resulting in high
efficiency even at load currents of 300µA or less.
If the output load increases sufficiently, A1’s output remains
high, resulting in continuous operation. When the LT1317
is running continuously, peak switch current is controlled
by VC to regulate the output voltage. The switch is turned
on at the beginning of each switch cycle. When the summation of a signal representing switch current and a ramp
generator (introduced to avoid subharmonic oscillations at
duty factors greater than 50%) exceeds the VC signal,
comparator A2 changes state, resetting the flip-flop and
turning off the switch. Output voltage increases as switch
current is increased. The output, attenuated by a resistor
divider, appears at the FB pin, closing the overall loop.
Frequency compensation is provided by an external series
RC network and an optional capacitor connected between
the VC pin and ground.
Low-battery detector A4’s open collector output (LBO) pulls
low when the LBI pin voltage drops below 200mV. There
is no hysteresis in A4, allowing it to be used as an amplifier
in some applications. The low-battery detector remains
active in shutdown. To enable the converter, SHDN must
be left floating or tied to a voltage between 1.4V and 6V.
7
LT1317/LT1317B
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APPLICATIONS INFORMATION
The LT1317B differs from the LT1317 in that the bias point
on A1 is set lower than on the LT1317 so that minimum
switch current can drop below 50mA. Because A1’s bias
point is set lower, there is no Burst Mode operation at light
loads and the device continues switching at constant
frequency. This results in the absence of low frequency
output voltage ripple at the expense of light load efficiency.
The difference between the two devices is clearly illustrated in Figure 2. The top two traces in Figure 2 show an
LT1317/LT1317B circuit, using the components indicated
in Figure 1, set to a 3.3V output. Input voltage is 2V. Load
current is stepped from 2mA to 200mA for both circuits.
Low frequency Burst Mode operation voltage ripple is
observed on Trace A, while none is observed on Trace B.
TRACE A
TRACE B
ILOAD
1
2
8
LT1317
7
3
6
4
5
L
D
CIN
MULTIPLE
VIAs
VIN
COUT
GND
VOUT
1317 F03
Figure 3. Recommended Component Placement. Traces Carrying
High Current Are Direct. Trace Area at FB Pin and VC Pin is Kept
Low. Lead Length to Battery Should be Kept Short.
COMPONENT SELECTION
LT1317
VOUT
100mV/DIV
AC COUPLED
LT1317B
VOUT
100mV/DIV
AC COUPLED
Inductors
200mA
2mA
1ms/DIV
1317 F02
Figure 2. LT1317 Exhibits Ripple at 2mA Load
During Burst Mode Operation, the LT1317B Does Not
LAYOUT HINTS
The LT1317 switches current at high speed, mandating
careful attention to layout for proper performance. You
will not get advertised performance with careless layouts.
Figure 3 shows recommended component placement.
Follow this closely in your PC layout. Note the direct path
of the switching loops. Input capacitor CIN must be placed
close (< 5mm) to the IC package. As little as 10mm of wire
or PC trace from CIN to VIN will cause problems such as
inability to regulate or oscillation.
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GROUND PLANE
Inductors appropriate for use with the LT1317 must
possess three attributes. First, they must have low core
loss at 600kHz. Most ferrite core units have acceptable
losses at this switching frequency. Inexpensive iron powder cores should be viewed suspiciously, as core losses
can cause significant efficiency penalties at 600kHz. Second, the inductor must be able to handle peak switch
current of the LT1317 without saturating. This places a
lower limit on the physical size of the unit. Molded chokes
or chip inductors usually do not have enough core to
support the LT1317 maximum peak switch current and are
unsuitable for the application. Lastly, the inductor should
have low DCR (copper wire resistance) to prevent efficiency-killing I2R losses. Linear Technology has identified
several inductors suitable for use with the LT1317. This is
not an exclusive list. There are many magnetics vendors
whose components are suitable for use. A few vendor’s
components are listed in Table 1.
LT1317/LT1317B
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APPLICATIONS INFORMATION
Table 1. Inductors Suitable for Use with the LT1317
PART
VALUE
MAX
DCR
MFR
HEIGHT
(mm)
LQH3C100
10µH
0.57
Murata-Erie
2.0
DO1608-103
10µH
0.16
Coilcraft
3.0
CD43-100
10µH
0.18
Sumida
3.2
CD54-100
10µH
0.10
Sumida
4.5
Best Efficiency
CTX32CT-100 10µH
0.50
Coiltronics
2.2
1210 Footprint
COMMENT
Smallest Size,
Limited Current
Handling
Capacitor Selection
Low ESR (Equivalent Series Resistance) capacitors should
be used at the output of the LT1317. For most applications
a solid tantalum in a C or D case size works well. Acceptable capacitance values range from 10µF to 330µF with
ESR falling between 0.1Ω and 0.5Ω. If component size is
an issue, tantalum capacitors in smaller case sizes can be
used but they have high ESR and output voltage ripple may
reach unacceptable levels.
Ceramic capacitors are an alternative because of their
combination of small size and low ESR. A 10µF ceramic
capacitor will work for some applications but the extremely low ESR of these capacitors may cause loop
stability problems. Compensation components will need
L1
10µH
to be adjusted to ensure a stable system for the entire input
voltage range. Figure 4 shows a 2V to 3.3V converter with
new values for RC and CC. Figure 5 details transient
response for this circuit. Also, ceramic caps are prone to
temperature effects and the designer must check loop
stability over the operating temperature range (see section
on Frequency Compensation).
Input bypass capacitor ESR is less critical and smaller
units may be used. If the input voltage source is physically
near the VIN pin (5ms.
Figure 8’s circuit has reduced C giving a shorter settling
time but still overdamped. Figure 9 shows the results
when C is reduced to the point where the system becomes
underdamped. The output voltage responds quickly
(≈200µs to 300µs) but some ringing exists. Figure 10 has
VOUT
3.3V
VIN
47µF
CC2
100pF
1M
15Ω
2W
+
47µF
GND
604k
R
50Ω
C
1317 F06
Figure 6. Frequency Response Test Setup
optimum R and C values giving the best possible settling
time with adequate phase margin.
An additional 100pF capacitor (CC2) is connected to the VC
pin and is necessary if the LT1317 is operated near current
limit. Also, CC2 should be present when higher ESR output
capacitors are used.
ILOAD
2mA TO
200mA
ILOAD
2mA TO
200mA
5ms/DIV
1317 F07
1317 F08
Figure 8. Reducing C to 22nF
Speeds Up the Response. (R = 33k)
Figure 7. With C = 56nF and R = 33k,
the System is Highly Overdamped.
VOUT
100mV/DIV
AC COUPLED
VOUT
100mV/DIV
AC COUPLED
ILOAD
2mA TO
200mA
ILOAD
2mA TO
200mA
1317 F09
Figure 9. Using 680pF for C Results in an
Underdamped System with Ringing. (R = 33k)
10
FB
SHDN
VC
VOUT
100mV/DIV
AC COUPLED
1ms/DIV
SW
LT1317
+
VOUT
100mV/DIV
AC COUPLED
5ms/DIV
MBR0520L
VIN
2V
1ms/DIV
1317 F10
Figure 10. 3.3nF and 33k Gives the
Shortest Settling Time with No Ringing.
LT1317/LT1317B
U
U
W
U
APPLICATIONS INFORMATION
LOW-BATTERY DETECTOR
The LT1317’s low-battery detector is a simple PNP input
gain stage with an open collector NPN output. The negative input of the gain stage is tied internally to a 200mV
±5% reference. The positive input is the LBI pin. Arrangement as a low-battery detector is straightforward.
Figure 11 details hookup. R1 and R2 need only be low
enough in value so that the bias current of the LBI pin
doesn’t cause large errors. For R2, 100k is adequate. The
200mV reference can also be accessed as shown in
Figure 12. The low-battery detector remains active in
shutdown.
3.3V
R1
VIN
LBI
LT1317
1M
+
LBO
R2
100k
TO PROCESSOR
–
200k
200mV
INTERNAL
REFERENCE
GND
V – 200mV
R1 = LB
2µA
2N3906
LT1317
VREF
200mV
LBI
+
10k
1317 F11
VIN
LBO
10µF
GND
1317 F12
Figure 11. Setting Low-Battery Detector Trip Point
Figure 12. Accessing 200mV Reference
U
TYPICAL APPLICATIO S
Single Li-Ion Cell to 3.3V SEPIC Converter
C3
1µF
L1A*
3.3V SEPIC Efficiency
80
MBR0520
SINGLE
Li-ION
CELL
(2.7V TO
4.2V)
C1
47µF
VIN
SW
FB
LT1317
SHDN
VC
GND
33k
L1B*
VOUT
3.3V
250mA
1M
1%
+
604k
1%
C2
47µF
EFFICIENCY (%)
75
+
70
65
60
VIN = 2.7V
VIN = 3.5V
55
VIN = 4.2V
3300pF
C1, C2: AVX TPSC476M010
C3: AVX 1206YC106KAT
* COILTRONICS CTX20-1
50
1317 TA03
1
10
100
LOAD CURRENT (mA)
1000
1317 TA03a
11
LT1317/LT1317B
U
TYPICAL APPLICATIO S
5V to 12V Boost Converter
L1
22µH
5V to 12V Boost Converter Efficiency
90
MBR0520
VIN
+
47µF
VOUT
12V
150mA
SW
FB
LT1317
SHUTDOWN
SHDN
VC
85
EFFICIENCY (%)
VIN
5V
1.07M
1%
LB0
GND
+
C2
47µF
124k
1%
56k
80
75
3300pF
70
L1: SUMIDA CD54-220
1317 TA04
10
LOAD CURRENT (mA)
1
100
1317 TA04a
Single Li-Ion to 5V DC/DC Converter
L1
10µH
Single Li-Ion to 5V DC/DC Converter Efficiency
90
MBR0520
47µF
SINGLE
Li-ION
CELL
(2.7V TO
4.2V)
VIN
LT1317
SHUTDOWN
SHDN
VC
SW
FB
EFFICIENCY (%)
85
+
VOUT
5V
250mA
1M
1%
GND
+
47µF
75
70
VIN = 2.7V
324k
1%
33k
80
VIN = 3.5V
65
3300pF
VIN = 4.2V
60
L1: SUMIDA CD43-100
1
1317 TA05
10
100
LOAD CURRENT (mA)
1000
1317 TA05a
Low Profile 3.3 to 5V Converter
L1
10µH
D1
3.3V
5V
125mA
VIN
+
C1
15µF
10V
SW
FB
LT1317BCMS8
SHDN
VC
1M
GND
33k
332k
C2
10µF
CERAMIC
3.3nF
C1: AVX TAJA156M010
C2: MURATA GRM235Y5V106Z01
L1: MURATA LQH3C100 OR SUMIDA CLQ61-100N
D1: MOTOROLA MBR0520LT1
12
1317 TA06
LT1317/LT1317B
U
TYPICAL APPLICATIO S
2-Cell to 5V DC/DC Converter with Undervoltage Lockout
L1
10µH
D1
5V
130mA
301k
+
100k
VIN
22µF
10V
LT1317
SW
FB
VC
SHDN
2 ALKALINE
CELLS
LBO
LBI
1M
340k
1M
1%
GND
33k
332k
1%
+
100µF
10V
3.3nF
470pF
D1: MOTOROLA MBR0520LT1
L1: SUMIDA CD43-101
1317 TA07
STARTS AT VIN = 1.9V
STOPS AT VIN = 1.6V
Universal Wall Cube to 4.1V
L1A
20µH
VIN
1.5V TO
10V
100k
+
VIN
15µF
20V
LT1317
SHDN
VC
CERAMIC
10µF, 16V
D1
VOUT
4.1V
110mA
SW
FB
L1B
GND
1M
1%
+
Q1
432k
1%
33k
47µF
10V
3.3nF
D1: MOTOROLA MBR0520LT1
L1: COILTRONICS CTX20-1
Q1: 2N3904
1317 TA08
2 Li-Ion to 8.2V DC/DC Converter
L1
22µH
+
D1
8.2V
400mA
22µF
16V
VIN
SW
LT1317/LT1317B
2 Li-ION
CELLS
(5.8V TO
8.4V)
SHUTDOWN
1M
+
FB
SHDN
VC
100pF
22pF
47µF
16V
GND
178k
33k
3.3nF
D1: MOTOROLA MBR0520LT1
L1: SUMIDA CD43-220
1317 TA09
13
LT1317/LT1317B
U
TYPICAL APPLICATIO S
Single Li-Ion Cell to 4V/70mA, – 4V/10mA
D2
4.5V TO 2.5V
1µF
CERAMIC
VIN
SW
LT1317
Li-Ion
CELL
SHUTDOWN
SHDN
VC
+
1µF
CERAMIC
L1
22µH
– 4V
10mA
C3
15µF
C1
1µF
L2
22µH
D1
1.00M
4V
70mA
FB
GND
+
100pF
33k
442k
C2
33µF
3.3nF
C1: MURATA GRM235Y5V107Z01
C2: AVX TAJB336M010
C3: AVX TAJA156M010
D1: MBR0520
D2: BAT54S (DUAL DIODE)
L1, L2: MURATA LQH3C220K04
1317 TA02
Low Noise 33V Varactor Bias Supply
D3
680Ω
150pF
D2
L1
22µH
C3
0.1µF
D1
VIN
3V TO 6V
VIN
+
C1
15µF
10V
SW
FB
150k
47Ω
VOUT
33V
0mA TO 10mA
LT1317B
GND
VC
33k
C4
0.1µF
5.9k
+
C2
10µF
35V
C5
0.1µF
C6
0.1µF
3300pF
C1: AVX TAJ156M010
C2: SANYO 35CV33GX
C3, C4, C5, C6: 0.1µF CERAMIC
D1, D2, D3: MOTOROLA MMBD914LT1
L1: MURATA LQH3C220
14
1317 TA11
LT1317/LT1317B
U
PACKAGE DESCRIPTION
Dimensions in inches (millimeters) unless otherwise noted.
MS8 Package
8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
0.118 ± 0.004*
(3.00 ± 0.102)
8
7 6
5
0.118 ± 0.004**
(3.00 ± 0.102)
0.192 ± 0.004
(4.88 ± 0.10)
1
2 3
4
0.040 ± 0.006
(1.02 ± 0.15)
0.007
(0.18)
0.034 ± 0.004
(0.86 ± 0.102)
0° – 6° TYP
SEATING
PLANE 0.012
(0.30)
0.0256
REF
(0.65)
TYP
0.021 ± 0.006
(0.53 ± 0.015)
0.006 ± 0.004
(0.15 ± 0.102)
MSOP (MS8) 1197
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH,
PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 – 0.197*
(4.801 – 5.004)
8
7
6
5
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
1
0.010 – 0.020
× 45°
(0.254 – 0.508)
0.008 – 0.010
(0.203 – 0.254)
2
3
4
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0°– 8° TYP
0.016 – 0.050
0.406 – 1.270
0.014 – 0.019
(0.355 – 0.483)
0.050
(1.270)
TYP
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
SO8 0996
15
LT1317/LT1317B
U
TYPICAL APPLICATION
Digital Camera Power Supply
10k
24V
D3
T1
7
+
LC
8
18V
3mA
C5
10µF
35V
D2
5
+
LB
6
LPRI:15µH
+
C1
22µF
10V
4 AA
CELLS
(3.2V TO
6.5V)
SHUTDOWN
2
D1
3
+
LA
1
4
C3
1µF, 16V
VIN
5V
20mA
C4
22µF
10V
C2
100µF
6V
3.3V
150mA
SW
LT1317
SHDN
1M
FB
GND
VC
10k
604k
3300pF
1317 TA10
C1, C4: AVX TPSC226M016
C2: AVX TPSC106M006
C3: CERAMIC (i.e. AVX, MANY OTHERS)
C5: SANYO 35CV10GX
D1, D2: MBR0520LT1 (MOTOROLA) OR EQUIVALENT
D3: MMBD914LT1 (MOTOROLA) OR EQUIVALENT
T1: COILTRONICS CTX02-14272-X1
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC 1163
Triple High Side Driver for 2-Cell Inputs
1.8V Minimum Input, Drives N-Channel MOSFETs
LTC1174
Micropower Step-Down DC/DC Converter
94% Efficiency, 130µA IQ, 9V to 5V at 300mA
LT1302
High Output Current Micropower DC/DC Converter
5V/600mA from 2V, 2A Internal Switch, 200µA IQ
LT1304
2-Cell Micropower DC/DC Converter
Low-Battery Detector Active in Shutdown
LT1307
Single Cell Micropower 600kHz PWM DC/DC Converter
3.3V at 75mA from 1 Cell, MSOP Package
LTC1440/1/2
Ultralow Power Single/Dual Comparators with Reference
2.8µA IQ, Adjustable Hysteresis
LTC1516
2-Cell to 5V Regulated Charge Pump
12µA IQ, No Inductors, 5V at 50mA from 3V Input
LT1521
Micropower Low Dropout Linear Regulator
500mV Dropout, 300mA Current, 12µA IQ
®
16
Linear Technology Corporation
13177bf LT/TP 1198 4K • PRINTED IN THE USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com
LINEAR TECHNOLOGY CORPORATION 1998
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