LT1317BCMS8 Linear Technology, LT1317BCMS8 Datasheet - Page 11

• Manufacturer Part Number: LT1317BCMS8
• Description: IC BOOST ADJ .5A 8MSOP
• Manufacturer: Linear Technology
• Type: Step-Up (Boost)r

Specifications of LT1317BCMS8

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 1.24 ~ 30 V
• Current - Output: 500mA
• Frequency - Switching: 620kHz
• Voltage - Input: 1.5 ~ 12 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -

APPLICATIONS
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
ment as a low-battery detector is straightforward.
TYPICAL APPLICATIO S
(2.7V TO
SINGLE
5% reference. The positive input is the LBI pin. Arrange-
Li-ION
CELL
4.2V)
Figure 11. Setting Low-Battery Detector Trip Point
C1, C2: AVX TPSC476M010
C3: AVX 1206YC106KAT
* COILTRONICS CTX20-1
R1
R2
100k
+
Single Li-Ion Cell to 3.3V SEPIC Converter
C1
47 F
LBI
GND
200mV
INTERNAL
REFERENCE
U
+
–
SHDN
V
V
IN
C
V
33k
IN
LT1317
3300pF
INFORMATION
L1A*
U
LT1317
GND
SW
FB
LBO
1317 F11
1 F
C3
U
W
3.3V
L1B*
1M
R1 =
MBR0520
TO PROCESSOR
V
604k
1%
LB
1%
1M
– 200mV
2 A
U
+
1317 TA03
C2
47 F
V
3.3V
250mA
OUT
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.
200mV
Figure 12. Accessing 200mV Reference
V
80
75
70
65
60
55
50
2N3906
REF
1
3.3V SEPIC Efficiency
10k
LOAD CURRENT (mA)
+
10
V
V
V
200k
IN
IN
IN
10 F
LT1317/LT1317B
= 2.7V
= 3.5V
= 4.2V
LBO
LBI
100
LT1317
GND
V
IN
1317 F12
1317 TA03a
1000
11