ST763A series
3.3V Step down current mode PWM DC-DC converters
Features
Output voltage 3.3V Supply voltage range from 3.3V to 11V Guaranteed output current: 500mA Typical operation frequency: 200KHz Very low quiescent current: 0.6mA on mode 0.2A OFF MODE Switch ON/OFF control Typical efficiency: 90% Operating temperature range: -40C to 85C Available in SO-8 package variations. A minimum number of external components is used and the fixed frequency switching allows easy filtering of output ripple and noise. Other features of this device are cycle-by-cycle current limiting, overcurrent limiting, under voltage lockout and programmable soft-start protection. A 22H inductor works in most applications, so no sophisticated design is necessary. Package available is SO-8. Typical application are in 5V to 3.3V converters, cellular phones, portable instruments, hand-held computers, and peripherals.
SO-8
Description
The ST763A is a step-down switching regulator. It operates from 3.3V to 11V giving a fixed 3.3V output voltage, delivering up to 500mA. The mainly features are typical efficiency of 90%, quiescent current of 0.6mA, and only 0.2A in shut-down. The PWM current mode control provides precise output regulation and very good transient response. Output voltage accuracy is guaranteed to be 5% over line, load and temperature
Order code
Part number ST763AC May 2007 Rev. 3 Packaging ST763ACDTR 1/14
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ST763A series
Contents
1 2 3 4 5 6 7 8 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
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Diagram
1
Figure 1.
Diagram
Schematic diagram
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Pin configuration
ST763A series
2
Figure 2.
Pin configuration
Pin connections (top view)
Table 1.
Pin N 1 2 3 4 5 6 7 8
Pin description
Symbol SHDN REF SS CC OUT GND LX VCC Name and function Shutdown control (active low): If connected to GND the IC is in shutdown. Connect to VCC for normal operation (ON MODE). Reference output voltage: (1.25V): Bypass to GND with 47nF capacitor. Soft start: a capacitor between SS and GND provides soft-start and short-circuit protections. Compensation capacitor input: externally compensates the outer (voltage) feedback loop. Connect to OUT with 330pF capacitor Output voltage sense input: provides regulation of feedback sensing. Connect to 3.3V output. Ground Switch output. Drain of internal P-channel power MOSFET Supply voltage input. Bypass to GND with 1F ceramic capacitance and large value electrolytic capacitor in parallel. The 1F capacitor must be as close as possible to the GND and VCC pins.
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Maximum ratings
3
Table 2.
Symbol VCC VLX VSHDN VS,VC ILX IREF PTOT Tstg Top
Maximum ratings
Absolute maximum ratings
Parameter DC input voltage Switch pin voltage Shutdown voltage (SHDN) Soft start (SS) and compensation capacitor (CC) pins voltage Switching peak current Reference current Continuous power dissipation at TA = 70C Storage temperature range Operating junction temperature range AC series SO-8 Value -0.3 to 12 -0.3 to (VCC + 0.3) -0.3 to (VCC + 0.3) -0.3 to (VCC + 0.3) 2 2.5 344 -40 to +150 0 to +70 Unit V V V V A mA mW C C
Note:
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied Thermal data
Parameter Thermal resistance junction-ambient (1) SO-8 160 Unit C/W
Table 3.
Symbol RthJA
1. This value depends from thermal design of PCB on which the device is mounted.
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Typical application
ST763A series
4
Figure 3.
Typical application
Application circuit
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Electrical characteristics
5
Table 4.
Symbol VCC VO VO VO
Electrical characteristics
Electrical characteristics (VCC = 5V, IO = 0mA, TA = TMIN to TMAX, unless otherwise specified).
Parameter Input voltage Output voltage Line regulation Load regulation Power efficiency IO = 0 to 500mA IO = 300mA IO = 100mA ON Mode (Including switch current) VCC = 4 to 11V, IO = 0 to 300mA VCC = 4.75 to 11V, IO = 0 to 500mA Test conditions Min. 3.3 3.135 3.135 3.3 3.3 0.13 0.005 88 % 90 0.6 0.2 2 0.25 1 VCC Falling ILX = 500mA VCC = 12V, VLX = 0V TA = 25C TA = TMIN to TMAX TA = 25C 159 1.18 2.7 1 10 1.25 50 200 7500 212.5 1.32 3 2.5 100 mA A V V A V Typ. Max. 11 3.465 3.465 Unit V V V %/V %/mA
ISUPPLY Supply current VIH VIL ISHDN VLOCK SHDN Input high threshold SHDN Input low threshold Shutdown input leakage current Under voltage lockout
OFF Mode
RDS(on) LX On resistance I LEAK VREF VREF fOSC RC LX Leakage current Reference voltage Temperature reference drift Switching frequency Compensation pin impedance
nA V ppm/C KHz
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Typical performance characteristics
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6
Figure 4.
Typical performance characteristics
(Unless otherwise specified TJ = 25C) Output voltage vs temperature Figure 5. Output voltage vs input voltage
Figure 6.
Reference voltage vs temperature
Figure 7.
Efficiency vs temperature
Figure 8.
Efficiency vs output current
Figure 9.
LX leakage current vs temperature
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Typical performance characteristics
Figure 10. LX ON Resistance vs temperature
Figure 11. Shutdown input threshold vs temperature
Figure 12. Shutdown input leakage current vs Figure 13. Oscillator frequency vs temperature temperature
Figure 14. Oscillator frequency vs input voltage
Figure 15. Switching waveform, continuous conduction
VI = 6V, IO = 250mA
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Package mechanical data
ST763A series
7
Package mechanical data
In order to meet environmental requirements, ST offers these devices in ECOPACK packages. These packages have a Lead-free second level interconnect. The category of second Level Interconnect is marked on the package and on the inner box label, in compliance with 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.
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Package mechanical data
SO-8 MECHANICAL DATA
DIM. A A1 A2 B C D E e H h L k ddd 0.1 5.80 0.25 0.40 mm. MIN. 1.35 0.10 1.10 0.33 0.19 4.80 3.80 1.27 6.20 0.50 1.27 0.228 0.010 0.016 TYP MAX. 1.75 0.25 1.65 0.51 0.25 5.00 4.00 MIN. 0.053 0.04 0.043 0.013 0.007 0.189 0.150 0.050 0.244 0.020 0.050 inch TYP. MAX. 0.069 0.010 0.065 0.020 0.010 0.197 0.157
8 (max.)
0.04
00160 23/C
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Package mechanical data
ST763A series
Tape & Reel SO-8 MECHANICAL DATA
mm. DIM. MIN. A C D N T Ao Bo Ko Po P 8.1 5.5 2.1 3.9 7.9 12.8 20.2 60 22.4 8.5 5.9 2.3 4.1 8.1 0.319 0.216 0.082 0.153 0.311 TYP MAX. 330 13.2 0.504 0.795 2.362 0.882 0.335 0.232 0.090 0.161 0.319 MIN. TYP. MAX. 12.99 2 0.519 inch
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Revision history
8
Table 5.
Date
Revision history
Revision history
Revision 2 3 Changes Add TA row fOSC on table 4 and new template. Order code has been updated.
26-May-2006 29-May-2007
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