Table of Contents
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General features
■
0.8V start up input voltage
■
Up to 5.5V operating input voltage
■
Internal synchronous rectifier
■
Adjustable output voltage from 1.8V to 5.5V
■
3.3V and 5V fixed output voltages
■
Low battery voltage detection
■
Reverse battery protection
■
550mA minimum input current limit
■
Switching frequency up to 1MHz
■
1.23V reference voltage available
Applications
■
Conversion from 1 to 3 alkaline,
■
NiMH, NiCd battery cells or 1 lithium ION
■
PDA and handheld instruments
■
Digital cameras
■
Cellular phones
■
GPS
■
Distributed power
Application circuit
June 2006
Synchronous rectifier step up converter
Description
The L6920DC is a high efficiency monolithic step
up switching converter IC especially designed for
battery powered application.
Package is MSOP8 in order to minimize PCB
space. It requires only three external components
to realize the conversion from the battery voltage
to the selected output voltage.
The minimum output voltage is 1.8V: suitable to
supply the most advanced ASIC and µP.
High switching frequency allows for a low profile,
small sized inductor and output capacitor to be
used.
Reference voltage, low battery detection and
Shutdown are provided together with over current,
over voltage.
L6920DC
Rev 1
L6920DC
MSOP8
3.3V
www.st.com
1/16
16
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Table of Contents
Related Manuals for ST L6920DC
Summary of Contents for ST L6920DC
- Page 1 3.3V and 5V fixed output voltages Description ■ Low battery voltage detection ■ Reverse battery protection The L6920DC is a high efficiency monolithic step up switching converter IC especially designed for ■ 550mA minimum input current limit battery powered application. ■...
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Page 2: Table Of Contents
Contents L6920DC Contents Pin settings ..........3 Pin connection . -
Page 3: Pin Settings
L6920DC Pin settings Pin settings Pin connection Figure 1. Pin connection (top view) Pin description Table 1. Pin description N° Type Description Output voltage selector. Connect FB to GND for Vout=5V or to OUT for Vout=3.3V. Connect FB to an external resistor divider for adjustable output voltage Battery low voltage detector input. -
Page 4: Electrical Data
Electrical data L6920DC Electrical data Maximum ratings Table 2. Absolute maximum ratings Symbol Parameter Value Unit to GND ccmax LBI, SHDN, FB to GND Vout to GND out max Thermal data Table 3. Thermal data Symbol Parameter Value Unit ° C/W... -
Page 5: Electrical Characteristics
L6920DC Electrical characteristics Electrical characteristics Table 4. Electrical characteristcs = 2V, FB = GND, T = 25°C unless otherwise specified) Symbol Parameter Test condition Unit Section Minimum Start Up Input = 3.3V Voltage = 0 mA, FB = 1.4V, V = 3.3V... -
Page 6: Typical Performance
Typical performance L6920DC Typical performance Figure 2. Efficiency vs output current @ V = 3.3V V in = 2 .4 V V in = 1 .2 V L6920DC L 6 9 2 0 D B V o u t= 3 .3 V L = 1 0µ... -
Page 7: Detailed Description
In L6920DC the control is based on a comparator that continuously checks the status of output voltage. If the output voltage is lower than the expected value, the control function of the L6920DC directs the energy stored in the inductor to be transferred to the load. This is accomplished by alternating between two basic steps: ●... - Page 8 Detailed description L6920DC So, in case of light load, the device works in PFM mode, as shown in Figure Figure 6. PFM mode condition: V = 5V; V =1.5V ; C2 = V ; C3 = Inductor batt Current Figure 7 shows how the device works in case of heavy load.
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Page 9: Start-Up
No regulation C2 = V ; C3 = Inductor Current Start-up One of the key features of L6920DC is the startup at supply voltage down to 0.8V (please see the diagram in Figure The device leaves the startup mode of operation as soon as Vout goes over 1.4V. During startup, the synchronous switch is off and the energy is transferred to the load through its intrinsic body diode. -
Page 10: Shutdown
Reverse polarity A protection circuit has been implemented to avoid that L6920DC and the battery are destroyed in case of wrong battery insertion. In addition, this circuit has been designed so that the current required by the battery is zero also in reverse polarity. - Page 11 L6920DC Detailed description Table 5. Output voltage connection = 3.3V FB pin connected to OUT (see application circuit) = 5V FB pin connected to GND ⎛ ⎞ ⋅ 1.8V < V < 5.5V FB pin connected to a resistive divider V 1.23V...
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Page 12: Package Mechanical Data
JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com... - Page 13 L6920DC Package mechanical data Table 6. MSOP8 Mechanical data inch Dim. 1.10 0.043 0.050 0.150 0.002 0.006 0.750 0.850 0.950 0.03 0.033 0.037 0.250 0.400 0.010 0.016 0.130 0.230 0.005 0.009 2.900 3.000 3.100 0.114 0.118 0.122 4.650 4.900 5.150 0.183...
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Page 14: Order Code
Order code L6920DC Order code Table 7. Order code Part number Package Packaging L6920DC MSOP8 Tube L6920DCTR MSOP8 Tape and reel 14/16... -
Page 15: Revision History
L6920DC Revision history Revision history Table 8. Revision history Date Revision Changes 29-Jun-2006 First issue 15/16... - Page 16 No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. If any part of this document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such third party products or services or any intellectual property contained therein.
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