LD2985Axx LD2985Bxx
Very low drop and low noise voltage regulator low ESR capacitors compatible, with inhibit function
Features
■ ■ ■ ■ ■ ■ ■ ■ ■ ■
Very low dropout voltage (280 mV at 150 mA and 7 mV at 1 mA load) Very low quiescent current (2 mA typ. at 150 mA load and 80 µA at no load) Output current up to 150 mA Logic controlled electronic shutdown Output voltage of 1.8, 2.5, 2.7, 2.8, 3, 3.3, 5 V Internal current and thermal limit Available in ± 1 % tolerance (at 25 °C, A version) Low output noise voltage 30 mVrms Smallest package SOT23-5L Temperature range: -40°C to 125 °C means that when the device is used as local regulator, it is possible to put a part of the board in standby, decreasing the total power consumption. An external capacitor, CBYP = 10 nF, connected between bypass pin and GND reduce the noise to 30 µVrms. Typical application are in cellular phone, palmtop laptop computer, personal digital assistant (PDA), personal stereo, camcorder and camera.
SOT23-5L
Description
The LD2985A/Bxx is a 150 mA fixed output voltage regulator. The ultra low drop voltage and the low quiescent current make them particularly suitable for low noise, low power applications, and in battery powered systems. In sleep mode quiescent current is less than 1 µA when INHIBIT pin is pulled low. Shutdown logic control function is available on pin 3 (TTL compatible). This Table 1. Device summary
Part numbers A Version LD2985AXX18 LD2985AXX25 LD2985AXX27 LD2985AXX28 LD2985AXX30 LD2985AXX33 LD2985AXX50 August 2008 B Version LD2985BXX18 LD2985BXX25 LD2985BXX27 LD2985BXX28 LD2985BXX30 LD2985BXX33 LD2985BXX50 Rev 10 Output voltages 1.8 V 2.5 V 2.7 V 2.8 V 3.0 V 3.3 V 5.0 V 1/21
www.st.com 21
LD2985Axx - LD2985Bxx
Contents
1 2 3 4 5 6 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Application notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.1 6.2 6.3 6.4 6.5 6.6 External capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Input capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Output capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Important . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Inhibit input operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Reverse current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7 8 9
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Order codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2/21
LD2985Axx - LD2985Bxx
Diagram
1
Figure 1.
Diagram
Schematic diagram
3/21
Pin configuration
LD2985Axx - LD2985Bxx
2
Figure 2.
Pin configuration
Pin connections (top view)
Table 2.
Pin n° 1 2 3 4 5
Pin description
Symbol IN GND INHIBIT Bypass OUT Input port Ground pin Control switch ON/OFF. Inhibit is not internally pulled-up; it cannot be left floating. Disable the device when connected to GND or to a positive voltage less than 0.18V Bypass pin: capacitor to be connected to GND in order to improve the thermal noise performances Output port Name and function
Table 3.
Symbol RthJC RthJA
Thermal data
Parameter Thermal resistance junction-case Thermal resistance junction-ambient SOT23-5L 81 255 Unit °C/W °C/W
4/21
LD2985Axx - LD2985Bxx
Maximum ratings
3
Table 4.
Maximum ratings
Absolute maximum ratings
Parameter DC input voltage INHIBIT input voltage Output current Power dissipation Storage temperature range Operating junction temperature range Value 16 16 Internally limited Internally limited -65 to 150 -40 to 125 °C °C Unit V V
Symbol VI VINH IO PD TSTG TOP
Note:
Absolute maximum ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied.
5/21
Electrical characteristics
LD2985Axx - LD2985Bxx
4
Table 5.
Symbol VOP VO
Electrical characteristics
Electrical characteristics for LD2985A (TJ = 25 °C, VI = VO + 1 V, IO = 50 mA, VSHDN = 2 V, CI = CO = 1 µF, unless otherwise specified).
Parameter Operating input voltage VI = 2.5V Output voltage IO = 1 to 150mA IO = 1 to 150mA, TJ= -40 to 125°C VI = 2.8V VO Output voltage IO = 1 to 150mA IO = 1 to 150mA, TJ= -40 to 125°C VI = 3.5V VO Output voltage IO = 1 to 50mA IO = 1 to 50mA, TJ= -40 to 125°C VI = 3.7V VO Output voltage IO = 1 to 150mA IO = 1 to 150mA, TJ= -40 to 125°C VI = 3.8V VO Output voltage IO = 1 to 150mA IO = 1 to 150mA, TJ= -40 to 125°C VI = 3.85V VO Output voltage IO = 1 to 150mA IO = 1 to 150mA, TJ= -40 to 125°C VI = 4.0V VO Output voltage IO = 1 to 150mA IO = 1 to 150mA, TJ= -40 to 125°C VI = 4.1V VO Output voltage IO = 1 to 150mA IO = 1 to 150mA, TJ= -40 to 125°C VI = 4.2V VO Output voltage IO = 1 to 150mA IO = 1 to 150mA, TJ= -40 to 125°C VI = 4.3V VO Output voltage IO = 1 to 150mA IO = 1 to 150mA, TJ= -40 to 125°C VI = 4.5V VO Output voltage IO = 1 to 150mA IO = 1 to 150mA, TJ= -40 to 125°C VI = 4.6V VO Output voltage IO = 1 to 150mA IO = 1 to 150mA, TJ= -40 to 125°C Test conditions Min. 2.5 1.478 1.462 1.447 1.773 1.755 1.737 1.463 2.4375 2.4125 2.660 2.6325 2.6055 2.758 2.730 2.702 2.808 2.778 2.750 2.955 2.925 2.895 3.054 3.022 2.9915 3.152 3.120 3.088 3.251 3.2175 3.1845 3.448 3.412 3.377 3.546 3.510 3.474 3.6 3.5 3.3 3.2 3.1 3.0 2.85 2.8 2.7 2.5 1.8 1.5 Typ. Max. 16 1.522 1.538 1.553 1.827 1.845 1.863 2.537 2.5625 2.5875 2.740 2.7675 2.7945 2.842 2.870 2.898 2.892 2.921 2.950 3.045 3.075 3.105 3.146 3.1775 3.2085 3.248 3.280 3.312 3.349 3.3825 3.4155 3.552 3.587 3.622 3.654 3.690 3.726 V V V V V V V V V V V V Unit V
6/21
LD2985Axx - LD2985Bxx Table 5.
Symbol
Electrical characteristics
Electrical characteristics for LD2985A (continued) (TJ = 25 °C, VI = VO + 1 V, IO = 50 mA, VSHDN = 2 V, CI = CO = 1 µF, unless otherwise specified).
Parameter VI = 4.8V Test conditions Min. 3.743 3.705 3.667 3.94 3.9 3.86 4.63 4.582 4.5355 4.925 4.875 4.825 400 0.003 0.014 0.032 1 7 40 120 280 80 100 200 600 2000 0 2 45 0.15 dB V 7/21 3 5 10 15 60 90 150 225 350 575 100 150 150 200 300 400 900 1200 3000 4000 µA mV %/VI 5 4.7 4 Typ. 3.8 Max. 3.857 3.895 3.933 4.06 4.1 4.14 4.77 4.817 4.8645 5.075 5.125 5.175 mA V V V V Unit
VO
Output voltage
IO = 1 to 150mA IO = 1 to 150mA, TJ= -40 to 125°C VI = 5.0V
VO
Output voltage
IO = 1 to 150mA IO = 1 to 150mA, TJ= -40 to 125°C VI = 5.7V
VO
Output voltage
IO = 1 to 150mA IO = 1 to 150mA, TJ= -40 to 125°C VI = 6.0V
VO ISC ΔVO/ΔVI
Output voltage Short circuit current Line regulation
IO = 1 to 150mA IO = 1 to 150 mA, TJ= -40 to 125°C RL = 0 VI = VO + 1V to 16V, IO = 1 mA VI = VO + 1V to 16V, IO = 1 mA, TJ= -40 to 125°C IO = 0 IO = 0, TJ= -40 to 125°C IO = 1mA IO = 1mA, TJ= -40 to 125°C IO = 10mA IO = 10mA, TJ= -40 to 125°C IO = 50mA IO = 50mA, TJ= -40 to 125°C IO = 150mA IO = 150mA, TJ= -40 to 125°C IO = 0 IO = 0, TJ= -40 to 125°C IO = 1mA IO = 1mA, TJ= -40 to 125°C
VDROP
Dropout voltage
Quiescent current ON MODE IQ
IO = 10mA IO = 10mA, TJ= -40 to 125°C IO = 50mA IO = 50mA, TJ= -40 to 125°C IO = 150mA IO = 150mA, TJ= -40 to 125°C VINH
