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LT1317/LT1317B Micropower, 600kHz PWM DC/DC Converters
FEATURES
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DESCRIPTION
The LT (R)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 300A 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. No-load quiescent current of the LT1317 is 100A and shuts down to 30A. 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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100A 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
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 10H
2-Cell to 3.3V Converter Efficiency
D1
90 2.2VIN 3VIN
+
C1 47F
VIN LBI LT1317 SHDN VC RC 33k CC 3.3nF
SW FB LBO GND R1 1M 1% R2* 604k 1%
3.3V 200mA
80
EFFICIENCY (%)
2 CELLS
SHUTDOWN
70
+
C2 47F
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
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1.65VIN
10 100 LOAD CURRENT (mA)
1000
1317 TA01
1
LT1317/LT1317B ABSOLUTE AXI U RATI GS
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
PACKAGE/ORDER I FOR ATIO
TOP VIEW VC FB SHDN GND 1 2 3 4 8 7 6 5 LBO LBI VIN SW
ORDER PART NUMBER LT1317CMS8 LT1317BCMS8
VC 1 FB 2 SHDN 3 GND 4
MS8 PACKAGE 8-LEAD PLASTIC MSOP TJMAX = 125C, JA = 160C/W
MS8 PART MARKING LTHA LTHB
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
Commercial Grade
SYMBOL IQ PARAMETER Quiescent Current
VIN = 2V, VSHDN = 2V, TA = 25C, unless otherwise noted.
CONDITIONS Not Switching, VSHDN = 2V (LT1317) VSHDN = 0V (LT1317/LT1317B) VSHDN = 2V, Switching (LT1317B) VSHDN = 2V, Switching (LT1317B)
q q q q
VFB IB gm AV
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 VIN = 2.5V, Duty Cycle = 30% VIN = 2.5V, Duty Cycle = 30% Duty Cycle = 30% (LT1317)
q q q q q
I = 5A
fOSC
Switching Frequency
2
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(Note 1)
Junction Temperature .......................................... 125C Operating Temperature Range Commercial ........................................... 0C to 70C Industrial ............................................ - 40C to 85C Storage Temperature Range ................ - 65C to 150C Lead Temperature (Soldering, 10 sec)................ 300C
TOP VIEW 8 7 6 5 LBO LBI VIN SW
ORDER PART NUMBER LT1317CS8 LT1317BCS8 LT1317IS8 LT1317BIS8 S8 PART MARKING 1317 1317B 1317I 1317BI
S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 125C, JA = 120C/W
MIN
TYP 100 25 4.8
MAX 160 40 6.5 7.5 1.26 1.26 60 12 240
UNITS A A mA mA V V nA V mhos 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
VIN = 2V, VSHDN = 2V, TA = 25C unless otherwise noted.
CONDITIONS VSHDN = VIN VSHDN = 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 A A mV mV V A nA V/V A 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 VCE Sat Reference Line Regulation SHDN Input Voltage High SHDN Input Voltage Low
ISINK = 10A VLBI = 250mV, VLBO = 5V VLBI = 150mV 1M Load VSW = 5V ISW = 500mA
q q q
q q
1.8V VIN 12V
q q q
0.08 1.4
Industrial Grade
SYMBOL IQ
VIN = 2V, VSHDN = 2V, - 40C TA 85C unless otherwise noted.
CONDITIONS Not Switching, VSHDN = 2V (LT1317) VSHDN = 0V (LT1317/LT1317B) VSHDN = 2V, Switching (LT1317B)
q q q q q q
PARAMETER Quiescent Current
MIN
TYP
MAX 160 40 7.5
UNITS A A mA V nA V mhos % mA kHz A A mV V A nA A mV %/V V V
VFB IB gm
Feedback Voltage FB Pin Bias Current (Note 2) Input Voltage Range Error Amp Transconductance Maximum Duty Cycle Switch Current Limit (Note 3) VIN = 2.5V, Duty Cycle = 30% VSHDN = VIN VSHDN = 0V ISINK = 10A VLBI = 250mV, VLBO = 5V VLBI = 150mV VSW = 5V ISW = 500mA 1.8V VIN 12V I = 5A
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
fOSC
Switching Frequency Shutdown Pin Current LBI Threshold Voltage LBO Output Low LBO Leakage Current LBI Input Bias Current (Note 4) Switch Leakage Current Switch VCE 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)
-40C 25C 600
SWITCH CURRENT (mA)
650 85C
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 (VCESAT) (mV)
LBI INPUT BIAS CURRENT (nA)
SWITCH CURRENT (mA)
TYPICAL 800
600 MINIMUM (25C) 400
200 0 20 40 60 DUTY CYCLE (%) 80 100
1317 TPC04
Feedback Voltage
1.25 203 202
LBI REFERENCE VOLTAGE (mV)
QUIESCENT CURRENT (A)
1.24
FEEDBACK VOLTAGE (V)
1.23
1.22
1.21
1.20 -50
-25
0 25 50 TEMPERATURE (C)
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10
1317 TPC01
Burst Mode Current Limit (LT1317)
800 VIN = 2V L = 10H 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 (VCESAT)
85C
25C -40C
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 (A)
FB PIN BIAS CURRENT (nA)
24 23 22 21 20 -50
28 24 20 16 12 8 4
SHDN PIN CURRENT (A)
-25
0 25 50 TEMPERATURE (C)
5V Output Efficiency, Circuit of Figure 1 (LT1317)
90
80
EFFICIENCY (%)
EFFICIENCY (%)
EFFICIENCY (%)
70
60 VIN = 1.65V VIN = 2.2V 50 0.3 1 VIN = 3V
10 100 LOAD CURRENT (mA)
Transient Response (LT1317)
VOUT 100mV/DIV AC COUPLED IL 200mA/DIV ILOAD 165mA 5mA VIN = 2V 1ms/DIV VOUT = 3.3V CIRCUIT OF FIGURE 1
1317 TPC16
UW
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
2 4 3 SHDN PIN VOLTAGE (V)
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 VIN = 1.65V 50 VIN = 2.2V VIN = 3V 40
60 VIN = 1.65V 50 VIN = 2.2V VIN = 3V 40
1000
1
10 100 LOAD CURRENT (mA)
1000
1317 TPC14
1
10 100 LOAD CURRENT (mA)
1000
1317 TPC15
Transient Response (LT1317B)
VOUT 100mV/DIV AC COUPLED IL 200mA/DIV ILOAD 165mA 5mA VIN = 2V 1ms/DIV VOUT = 3.3V CIRCUIT OF FIGURE 1 WITH LT1317B
1317 TPC17
Burst Mode Operation (LT1317)
VOUT 50mV/DIV AC COUPLED IL 200mA/DIV VSW 5V/DIV VIN = 2V 20s/DIV VOUT = 3.3V ILOAD = 30mA CIRCUIT OF FIGURE 1
1317 TPC18
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LT1317/LT1317B TYPICAL PERFOR A CE CHARACTERISTICS
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
Load Regulation (LT1317)
VOUT 50mV/DIV DC COUPLED OFFSET ADDED
VIN = 1.5V VOUT = 3.3V
ILOAD 25mA/DIV
Note: For load regulation pictures, double lines are due to output capacitor ESR.
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). 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 10A. A 1M pull-up is recommended.
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Load Regulation (LT1317)
VOUT 50mV/DIV DC COUPLED OFFSET ADDED
Load Regulation (LT1317)
1317 TPC19
VIN = 2V VOUT = 5V
ILOAD 25mA/DIV
1317 TPC20
VIN = 2.5V VOUT = 5V
ILOAD 50mA/DIV
1317 TPC21
Load Regulation (LT1317)
Load Regulation (LT1317)
VOUT 50mV/DIV DC COUPLED OFFSET ADDED
VOUT 50mV/DIV DC COUPLED OFFSET ADDED
1317 TPC22
VIN = 2V VOUT = 3.3V
ILOAD 50mA/DIV
1317 TPC23
VIN = 2.5V VOUT = 3.3V
ILOAD 50mA/DIV
1317 TPC24
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LT1317/LT1317B
BLOCK DIAGRAM
1.24V REFERENCE FB 2
VOUT BIAS R1 (EXTERNAL) FB RAMP GENERATOR
600kHz OSCILLATOR
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 100A. 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 300A 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.
+
+ +
-
R2 (EXTERNAL)
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LBI
+
gm
VC 1 200mV ENABLE
7
+ -
A4
LBO 8
-
ERROR AMPLIFIER
+ -
SHDN SHUTDOWN 3
A1 COMPARATOR SW 5 FF R A2 COMPARATOR S Q DRIVER Q3
+
A=2 0.08
-
4 GND
1317 BD
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LT1317/LT1317B
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 LT1317 VOUT 100mV/DIV AC COUPLED LT1317B VOUT 100mV/DIV AC COUPLED 200mA 2mA 1ms/DIV
1317 F02
TRACE B
ILOAD
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 1 2 3 4 LT1317 8 7 6 5 L VIN
MULTIPLE VIAs
CIN COUT GND
D
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 Inductors 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
APPLICATIONS INFORMATION
Table 1. Inductors Suitable for Use with the LT1317
PART LQH3C100 VALUE 10H MAX DCR 0.57 MFR Murata-Erie HEIGHT (mm) 2.0 COMMENT Smallest Size, Limited Current Handling
DO1608-103 CD43-100 CD54-100
10H 10H 10H
0.16 0.18 0.10 0.50
Coilcraft Sumida Sumida Coiltronics
3.0 3.2 4.5 2.2 Best Efficiency 1210 Footprint
CTX32CT-100 10H
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 10F to 330F with ESR falling between 0.1 and 0.5. 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 10F 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 10H VIN 2V VIN LT1317B C1 10F SHDN VC RC 20k CC 1500pF D1: MBR0520 L1: SUMIDA CD43-100 GND SW FB
D1 VOUT 3.3V
R1 1M 1% R2 604k 1%
C2 10F CERAMIC
1317 F04
Figure 4. 2V to 3.3V Converter with a 10F Ceramic Output Capacitor. RC and CC Have Been Adjusted to Give Optimum Transient Response.
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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 (<5mm), a 10F ceramic or a 10F A case tantalum is adequate. Diodes Most of the application circuits on this data sheet specify the Motorola MBR0520L surface mount Schottky diode. In lower current applications, a 1N4148 can be used, although efficiency will suffer due to the higher forward drop. This effect is particularly noticeable at low output voltages. For higher voltage output applications, such as LCD bias generators, the extra drop is a small percentage of the output voltage so the efficiency penalty is small. The low cost of the 1N4148 makes it attractive wherever it can be used. In through hole applications the 1N5818 is the all around best choice.
VOUT 200mV/DIV AC COUPLED
ILOAD 5mA TO 200mA 200s/DIV
1317 F05
Figure 5. Transient Response for the Circuit of Figure 4.
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LT1317/LT1317B
APPLICATIONS INFORMATION
FREQUENCY COMPENSATION The LT1317 has an external compensation pin (VC) which allows the frequency response to be optimized for the circuit configuration. In most cases, the values used in Figure 1 will work. Some circuits may need additional compensation and a simple trial and error method for determining the necessary component values is given. Figure 6 shows the test setup. A load step is applied and the resulting output voltage waveform is observed. Figures 7 through 10 detail the response for various values of R and C in the compensation network. The circuit of Figure 7 starts with a large C and small R giving a highly overdamped system. This system will always be stable but the output voltage displays a long settling time of >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 (200s to 300s) but some ringing exists. Figure 10 has
10H VIN 2V VIN SW LT1317 47F SHDN VC R 50 C
1317 F06
VOUT 100mV/DIV AC COUPLED
ILOAD 2mA TO 200mA 5ms/DIV
1317 F07
Figure 7. With C = 56nF and R = 33k, the System is Highly Overdamped.
VOUT 100mV/DIV AC COUPLED
ILOAD 2mA TO 200mA 1ms/DIV
1317 F09
Figure 9. Using 680pF for C Results in an Underdamped System with Ringing. (R = 33k)
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MBR0520L VOUT 3.3V 1M 15 2W 47F 604k
+
FB GND
+
CC2 100pF
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.
VOUT 100mV/DIV AC COUPLED
ILOAD 2mA TO 200mA 5ms/DIV
1317 F08
Figure 8. Reducing C to 22nF Speeds Up the Response. (R = 33k)
VOUT 100mV/DIV AC COUPLED
ILOAD 2mA TO 200mA 1ms/DIV
1317 F10
Figure 10. 3.3nF and 33k Gives the Shortest Settling Time with No Ringing.
LT1317/LT1317B
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 LBI R2 100k VIN LT1317 1M LBO TO PROCESSOR
+ -
200mV INTERNAL REFERENCE GND
1317 F11
V - 200mV R1 = LB 2A
Figure 11. Setting Low-Battery Detector Trip Point
TYPICAL APPLICATIO S
Single Li-Ion Cell to 3.3V SEPIC Converter
L1A* C3 1F
MBR0520
+
SINGLE Li-ION CELL (2.7V TO 4.2V)
LT1317 SHDN VC 33k 3300pF C1, C2: AVX TPSC476M010 C3: AVX 1206YC106KAT * COILTRONICS CTX20-1 GND L1B*
1M 1%
VOUT 3.3V 250mA
EFFICIENCY (%)
C1 47F
VIN
SW FB
604k 1%
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200k 2N3906 VREF 200mV 10k LBO
VIN LT1317
+
10F
LBI GND
1317 F12
Figure 12. Accessing 200mV Reference
3.3V SEPIC Efficiency
80 75 70 65 60 VIN = 2.7V 55 50
1317 TA03
+
C2 47F
VIN = 3.5V VIN = 4.2V 1 10 100 LOAD CURRENT (mA) 1000
1317 TA03a
11
LT1317/LT1317B
TYPICAL APPLICATIO S
5V to 12V Boost Converter
L1 22H VIN 5V MBR0520 VOUT 12V 150mA 1.07M 1% EFFICIENCY (%)
+
47F SHUTDOWN
VIN LT1317 SHDN VC 56k 3300pF L1: SUMIDA CD54-220
SW FB LB0 GND
Single Li-Ion to 5V DC/DC Converter
L1 10H MBR0520
+
47F SINGLE Li-ION CELL (2.7V TO 4.2V)
LT1317 SHUTDOWN SHDN VC 33k 3300pF L1: SUMIDA CD43-100
1M 1% GND 324k 1%
VOUT 5V 250mA
EFFICIENCY (%)
VIN
SW FB
12
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5V to 12V Boost Converter Efficiency
90
85
80
+
124k 1%
C2 47F
75
70
1317 TA04
1
10 LOAD CURRENT (mA)
100
1317 TA04a
Single Li-Ion to 5V DC/DC Converter Efficiency
90 85 80 75 70 VIN = 2.7V 65 60
1317 TA05
+
47F
VIN = 3.5V VIN = 4.2V 1 10 100 LOAD CURRENT (mA) 1000
1317 TA05a
Low Profile 3.3 to 5V Converter
L1 10H 3.3V VIN SW FB LT1317BCMS8 GND C2 10F CERAMIC D1 5V 125mA
+
C1 15F 10V
1M
SHDN VC 33k 3.3nF
332k
C1: AVX TAJA156M010 C2: MURATA GRM235Y5V106Z01 L1: MURATA LQH3C100 OR SUMIDA CLQ61-100N D1: MOTOROLA MBR0520LT1
1317 TA06
LT1317/LT1317B
TYPICAL APPLICATIO S
2-Cell to 5V DC/DC Converter with Undervoltage Lockout
L1 10H D1 5V 130mA 301k 100k VIN
2 ALKALINE CELLS
D1: MOTOROLA MBR0520LT1 L1: SUMIDA CD43-101 STARTS AT VIN = 1.9V STOPS AT VIN = 1.6V
VIN 1.5V TO 10V
2 Li-ION CELLS (5.8V TO 8.4V)
U
+
LT1317
SW FB VC GND 33k 3.3nF
1M 1%
22F 10V 1M
SHDN LBO LBI
332k 1%
+
100F 10V
340k
470pF
1317 TA07
Universal Wall Cube to 4.1V
L1A 20H CERAMIC 10F, 16V D1 VOUT 4.1V 110mA 1M 1%
+
100k 15F 20V
VIN LT1317 SHDN VC
SW FB L1B
GND
+
432k 1%
Q1 33k 3.3nF D1: MOTOROLA MBR0520LT1 L1: COILTRONICS CTX20-1 Q1: 2N3904
47F 10V
1317 TA08
2 Li-Ion to 8.2V DC/DC Converter
L1 22H D1 8.2V 400mA 22F 16V SHUTDOWN VIN SW 22pF 1M
+
LT1317/LT1317B SHDN VC 33k 3.3nF D1: MOTOROLA MBR0520LT1 L1: SUMIDA CD43-220 FB GND
+
178k
47F 16V
100pF
1317 TA09
13
LT1317/LT1317B
TYPICAL APPLICATIO S
Single Li-Ion Cell to 4V/70mA, - 4V/10mA
D2 C3 15F - 4V 10mA
4.5V TO 2.5V
L1 22H
1F CERAMIC Li-Ion CELL
VIN LT1317
SW
C1 1F 1.00M
SHUTDOWN
SHDN VC 33k 3.3nF
FB GND
100pF
442k
C1: MURATA GRM235Y5V107Z01 C2: AVX TAJB336M010 C3: AVX TAJA156M010 D1: MBR0520 D2: BAT54S (DUAL DIODE) L1, L2: MURATA LQH3C220K04
Low Noise 33V Varactor Bias Supply
D3 680 150pF D2 C3 0.1F D1
L1 22H VIN 3V TO 6V VIN SW FB LT1317B VC 33k 3300pF GND
150k
+
C1 15F 10V
C4 0.1F 5.9k
+
C1: AVX TAJ156M010 C2: SANYO 35CV33GX C3, C4, C5, C6: 0.1F CERAMIC D1, D2, D3: MOTOROLA MMBD914LT1 L1: MURATA LQH3C220
14
+
U
1F CERAMIC
L2 22H
D1 4V 70mA
+
C2 33F
1317 TA02
47 VOUT 33V 0mA TO 10mA C2 10F 35V C5 0.1F C6 0.1F
1317 TA11
LT1317/LT1317B
PACKAGE DESCRIPTION
0.007 (0.18) 0.021 0.006 (0.53 0.015)
* 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
0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254) 0- 8 TYP
0.016 - 0.050 0.406 - 1.270
*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.
U
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 76 5
0.192 0.004 (4.88 0.10)
0.118 0.004** (3.00 0.102)
1 0.040 0.006 (1.02 0.15) 0 - 6 TYP SEATING PLANE 0.012 (0.30) 0.0256 REF (0.65) TYP
23
4 0.034 0.004 (0.86 0.102)
0.006 0.004 (0.15 0.102)
MSOP (MS8) 1197
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
0.228 - 0.244 (5.791 - 6.197)
0.150 - 0.157** (3.810 - 3.988)
1 0.053 - 0.069 (1.346 - 1.752)
2
3
4
0.004 - 0.010 (0.101 - 0.254)
0.014 - 0.019 (0.355 - 0.483)
0.050 (1.270) TYP
SO8 0996
15
LT1317/LT1317B
TYPICAL APPLICATION
Digital Camera Power Supply
10k
4 AA CELLS (3.2V TO 6.5V) SHUTDOWN
C1, C4: AVX TPSC226M016 C2: AVX TPSC106M006 C3: CERAMIC (i.e. AVX, MANY OTHERS) C5: SANYO 35CV10GX
RELATED PARTS
PART NUMBER LTC 1163 LTC1174 LT1302 LT1304 LT1307 LTC1440/1/2 LTC1516 LT1521
(R)
DESCRIPTION Triple High Side Driver for 2-Cell Inputs Micropower Step-Down DC/DC Converter High Output Current Micropower DC/DC Converter 2-Cell Micropower DC/DC Converter Single Cell Micropower 600kHz PWM DC/DC Converter Ultralow Power Single/Dual Comparators with Reference 2-Cell to 5V Regulated Charge Pump Micropower Low Dropout Linear Regulator
16
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
U
24V D3 T1 7 LC 8 D2 5 LB 6 LPRI:15H 2 3 LA 1 4 C3 1F, 16V 1M FB GND 10k 3300pF
1317 TA10
+
C5 10F 35V
18V 3mA
+
D1
C4 22F 10V 3.3V 150mA
5V 20mA
+
C1 22F 10V
+
C2 100F 6V
VIN LT1317 SHDN VC
SW
604k
D1, D2: MBR0520LT1 (MOTOROLA) OR EQUIVALENT D3: MMBD914LT1 (MOTOROLA) OR EQUIVALENT T1: COILTRONICS CTX02-14272-X1
COMMENTS 1.8V Minimum Input, Drives N-Channel MOSFETs 94% Efficiency, 130A IQ, 9V to 5V at 300mA 5V/600mA from 2V, 2A Internal Switch, 200A IQ Low-Battery Detector Active in Shutdown 3.3V at 75mA from 1 Cell, MSOP Package 2.8A IQ, Adjustable Hysteresis 12A IQ, No Inductors, 5V at 50mA from 3V Input 500mV Dropout, 300mA Current, 12A IQ
13177bf LT/TP 1198 4K * PRINTED IN THE USA
(c) LINEAR TECHNOLOGY CORPORATION 1998

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