LT1307CS8 Linear Technology, LT1307CS8 Datasheet - Page 14

• Manufacturer Part Number: LT1307CS8
• Description: IC DC/DC CONV SINGLE CELL 8-SOIC
• Manufacturer: Linear Technology
• Type: Step-Up (Boost)r

Specifications of LT1307CS8

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 3.3V, 5V
• Current - Output: 100mA
• Frequency - Switching: 600kHz
• Voltage - Input: 1 ~ 5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -

APPLICATIO S I FOR ATIO
LT1307/LT1307B
REVERSE BATTERY CONSIDERATIONS
The LT1307 is built on a junction-isolated bipolar process.
The p-type substrate is connected to the GND pin of the
LT1307. Substrate diodes, normally reverse-biased, are
present on the SW pin and the V
16. When the battery polarity is reversed, these diodes
conduct, as illustrated in Figure 17. With a single AA or
AAA cell, several hundred milliamperes flow in the circuit.
The LT1307 can withstand this current without damage. In
laboratory tests, the LT1307 performed without degrada-
14
Figure 16. LT1307 Showing Internal Substrate Diodes D1 and D2.
In Normal Operation Diodes are Reverse-Biased
1.5V
1 CELL
U
LT1307
V
IN
D1
U
D2
Figure 18. 1N4001 Diode Protects LT1307 from Excessive Power
Dissipation When a 2- or 3-Cell Battery is Used
IN
Q1
SW
GND
pin as shown in Figure
W
1307 F16
2 OR 3
CELLS
U
1N4001
V
IN
tion after sustaining polarity reversal for the life of a single
AA alkaline cell.
When using a 2- or 3-cell supply, an external protection
diode is recommended as shown in Figure 18. When the
battery polarity is reversed, the 1N4001 conducts, limiting
reverse voltage across the LT1307 to a single diode drop.
This arrangement will quickly deplete the cells’ energy, but
it does prevent the LT1307 from excessive power dissipa-
tion and potential damage.
LT1307
GND
SW
Figure 17. When Cell Is Reversed Current Flows through
D1 and D2
1307 F18
– 1.5V
1 CELL
LT1307
V
IN
D1
CURRENT
FLOW
D2
Q1
SW
GND
1307 F17
1307fa