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PDF 317B Data sheet ( Hoja de datos )
| Número de pieza | 317B | |
| Descripción | Micropower/ 600kHz PWM DC/DC Converters | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de 317B (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
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LT1317/LT1317B
Micropower, 600kHz PWM
DC/DC Converters
FEATURES
s 100µA Quiescent Current
s Operates with VIN as Low as 1.5V
s 600kHz Fixed Frequency Operation
s Starts into Full Load
s Low-Battery Detector Active in Shutdown
s Automatic Burst Mode Operation at
Light Load (LT1317)
s Continuous Switching at Light Loads (LT1317B)
s Low VCESAT Switch: 300mV at 500mA
s Pin for Pin Compatible with the LT1307/LT1307B
U
APPLICATIONS
s Cellular Telephones
s Cordless Telephones
s Pagers
s GPS Receivers
s Battery Backup
s Portable Electronic Equipment
s Glucose Meters
s Diagnostic Medical Instrumentation
TYPICAL APPLICATION
L1
10µH
D1
+
C1
47µF
2 SHUTDOWN
CELLS
VIN SW
LBI FB
LT1317
SHDN
VC
LBO
GND
RC
33k
CC
3.3nF
R1
1M
1% +
R2*
604k
1%
3.3V
200mA
C2
47µF
D1: MBR0520
L1: SUMIDA CD43-100
* FOR 5V OUTPUT, R2 = 332k, 1%
1317 F01
Figure 1. 2-Cell to 3.3V Boost Converter
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 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, 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.
2-Cell to 3.3V Converter Efficiency
90
2.2VIN 3VIN
80
1.65VIN
70
60
50
40
0.3 1
10 100
LOAD CURRENT (mA)
1000
1317 TA01
1
1 page  
TYPICAL PERFOR A CE CHARACTERISTICS
LT1317/LT1317B
Quiescent Current, SHDN = 0V
26
25
24
23
22
21
20
–50 –25
0
25 50
TEMPERATURE (°C)
75 100
1317 TPC10
5V Output Efficiency, Circuit of
Figure 1 (LT1317)
90
FB Pin Bias Current
40
36
32
28
24
20
16
12
8
4
0
–50 –25
0
25 50
TEMPERATURE (°C)
75 100
1317 TPC11
2-Cell to 3.3V Converter
Efficiency (LT1317B)
90
SHDN Pin Current
2
1
0
–1
–2
–3
0123456
SHDN PIN VOLTAGE (V)
1317 TPC12
2-Cell to 5V Converter Efficiency
(LT1317B)
90
80 80
80
70
70
70
60
VIN = 1.65V
VIN = 2.2V
50 VIN = 3V
0.3 1
10 100
LOAD CURRENT (mA)
1000
1317 TPC13
60
50
40
1
VIN = 1.65V
VIN = 2.2V
VIN = 3V
10 100
LOAD CURRENT (mA)
1000
1317 TPC14
60
50
40
1
VIN = 1.65V
VIN = 2.2V
VIN = 3V
10 100
LOAD CURRENT (mA)
1000
1317 TPC15
Transient Response (LT1317)
VOUT
100mV/DIV
AC COUPLED
IL
200mA/DIV
Transient Response (LT1317B)
VOUT
100mV/DIV
AC COUPLED
IL
200mA/DIV
Burst Mode Operation (LT1317)
VOUT
50mV/DIV
AC COUPLED
IL
200mA/DIV
ILOAD
165mA
5mA
VIN = 2V
1ms/DIV
VOUT = 3.3V
CIRCUIT OF FIGURE 1
1317 TPC16
ILOAD
165mA
5mA
VIN = 2V
1ms/DIV
VOUT = 3.3V
CIRCUIT OF FIGURE 1
WITH LT1317B
1317 TPC17
VSW
5V/DIV
VIN = 2V
20µs/DIV
VOUT = 3.3V
ILOAD = 30mA
CIRCUIT OF FIGURE 1
1317 TPC18
5
5 Page 
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 nega-
tive input of the gain stage is tied internally to a 200mV
±5% reference. The positive input is the LBI pin. Arrange-
ment 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.
R1
LBI
R2
100k
VIN
+
–
LT1317
LBO
3.3V
1M
TO PROCESSOR
200mV
INTERNAL
REFERENCE
GND
1317 F11
R1 = VLB – 200mV
2µA
Figure 11. Setting Low-Battery Detector Trip Point
2N3906
200k
VREF
200mV
+
10k 10µF
VIN
LBO
LT1317
LBI
GND
1317 F12
Figure 12. Accessing 200mV Reference
TYPICAL APPLICATIO S
Single Li-Ion Cell to 3.3V SEPIC Converter
L1A*
C3
1µF
MBR0520
SINGLE
Li-ION
CELL
(2.7V TO
4.2V)
+
C1
47µF
VIN SW
FB
LT1317
SHDN
VC
GND
33k
3300pF
C1, C2: AVX TPSC476M010
C3: AVX 1206YC106KAT
* COILTRONICS CTX20-1
L1B*
1M
1%
+
604k
1%
VOUT
3.3V
250mA
C2
47µF
1317 TA03
3.3V SEPIC Efficiency
80
75
70
65
60
55
50
1
VIN = 2.7V
VIN = 3.5V
VIN = 4.2V
10 100
LOAD CURRENT (mA)
1000
1317 TA03a
11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet 317B.PDF ] | |
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