March 2009 Rev 1 1/24
24
LD39050xx
500 mA low quiescent current
low noise voltage regulator
Features
■Input voltage from 1.5 to 5.5 V
■Ultra low dropout voltage (200 mV typ. at 500
mA load)
■Very low quiescent current (20 µA typ. at no
load, 100 µA typ. at 500 mA load, 1 µA max in
off mode)
■Very low noise without bypass capacitor
■Output voltage tolerance: ± 2.0 % @ 25 °C
■500 mA guaranteed output current
■Wide range of output voltages available on
request: 0.8 V to 4.5 V with 100 mV step and
ADJ from 0.8 V
■Logic-controlled electronic shutdown
■Compatible with ceramic capacitor
COUT = 1 µF
■Internal current and thermal limit
■Package DFN6 (3 x 3 mm)
■Temperature range: -40 °C to 125 °C
Description
The LD39050 provides 500 mA maximum current
from an input voltage ranging from 1.5 V to 5.5 V
with a typical dropout voltage of 200 mV. Stability
is provided using ceramic capacitors. The ultra
low drop-voltage, low quiescent current and low
noise features make it suitable for low power
battery-powered applications. Power supply
rejection is 65 dB at low frequencies and starts to
roll off at 10 kHz. An Enable logic control function
puts the LD39050 in shut-down mode allowing a
total current consumption lower than 1 µA. The
device also includes short-circuit constant current
limiting and thermal protection. Typical
applications are mobile phones, personal digital
assistants (PDAs), cordless phones and similar
battery-powered systems.
DFN6 (3 x 3 mm)
Table 1. Device summary
Part numbers Order codes Output voltages
LD39050XX LD39050PUR ADJ from 0.8 V
LD39050XX10 LD39050PU10R 1.0 V
LD39050XX12 LD39050PU12R 1.2 V
LD39050XX25 LD39050PU25R 2.5 V
LD39050XX33 LD39050PU33R 3.3 V
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Contents LD39050xx
2/24
Contents
1 Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.1 Power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.2 Enable function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.3 Power Good function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8 Different output voltage versions of the LD39050xx
available on request . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
LD39050xx Diagrams
3/24
1 Diagrams
Figure 1. Schematic diagram for the LD39050PU
Current
limit
Thermal
protection
OUT
GND
OpAmp
IN Power-good
signal
PG
Internal
enable
IN
ADJ
EN
BandGap
reference Current
limit
Thermal
protection
OUT
GND
OpAmp
IN Power-good
signal
PG
Internal
enable
ININ
ADJ
EN
BandGap
reference
Figure 2. Schematic diagram for the LD39050PUxx
Current
limit
Thermal
protection
OUT
GND
OpAmp
IN Power-good
signal
PG
Internal
enable
IN
NC
EN
BandGap
reference
R1
R2
Current
limit
Thermal
protection
OUT
GND
OpAmp
IN Power-good
signal
PG
Internal
enable
ININ
NC
EN
BandGap
reference
R1
R2
Pin configuration LD39050xx
4/24
2 Pin configuration
Figure 3. Pin connection (top view)
LD39050PUxx
EN
GND
PG
VIN
NC
VOUT
EN
GND
PG
VIN
ADJ
VOUT
LD39050PU
Table 2. Pin description
Symbol
Pin n°
Function
LD39050PU LD39050PUxx
EN 1 1 Enable pin logic input: Low=shutdown, High=active
GND 2 2 Common ground
PG 3 3 Power Good
VOUT 4 4 Output voltage
ADJ 5 - Adjust pin
VIN 6 6 Input voltage of the LDO
NC - 5 Not connected
GND EXP pad Exposed pad must be connected to GND
LD39050xx Maximum ratings
5/24
3 Maximum ratings
Note: Absolute maximum ratings are those values beyond which damage to the device may occur.
Functional operation under these conditions is not implied. All values are referred to GND.
Table 3. Absolute maximum ratings
Symbol Parameter Value Unit
VIN DC input voltage -0.3 to 7 V
VOUT DC output voltage -0.3 to VI + 0.3 (7 V max) V
EN Enable pin -0.3 to VI + 0.3 (7 V max) V
PG Power Good pin -0.3 to 7 V
ADJ Adjust pin 4 V
IOUT Output current Internally limited
PDPower dissipation Internally limited
TSTG Storage temperature range - 65 to 150 °C
TOP Operating junction temperature range - 40 to 125 °C
Table 4. Thermal data
Symbol Parameter Value Unit
RthJA Thermal resistance junction-ambient 55 °C/W
RthJC Thermal resistance junction-case 10 °C/W
Table 5. ESD performance
Symbol Parameter Test conditions Value Unit
ESD ESD protection voltage HBM 2 kV
MM 0.3 kV
Electrical characteristics LD39050xx
6/24
4 Electrical characteristics
TJ = 25 °C, VIN = 1.8 V, CIN = COUT = 1 µF, IOUT = 10 mA, VEN = VIN, unless otherwise
specified.
Table 6. Electrical characteristics for the LD39050PU
Symbol Parameter Test conditions Min. Typ. Max. Unit
VIN Operating input voltage 1.5 5.5 V
VADJ VADJ accuracy IOUT =10 mA, TJ = 25°C 784 800 816 mV
IOUT = 10 mA, -40°C<TJ<125°C 776 800 824
IADJ Adjust pin current 1µA
ΔVOUT Static line regulation VOUT +1 V ≤ VIN ≤ 5.5 V,
IOUT = 1 mA 0.01 %/V
ΔVOUT Transient line regulation (1)
ΔVIN=500 mV, IOUT=10 mA, tR=5
µs 10 mVpp
ΔVIN=500 mV, IOUT=10 mA, tF=5 µs 10
ΔVOUT Static load regulation IOUT = 10 mA to 500 mA 0.002 %/mA
ΔVOUT Transient load regulation (1) IOUT = 10 mA to 500 mA, tR=5µs 40 mVpp
IOUT = 10 mA to 500 mA, tF=5µs 40
VDROP Dropout voltage (2) IO = 500mA, VOUT fixed to 1.5V
40°C<TJ<125°C 200 400 mV
eNOutput noise voltage 10Hz to 100kHz, IOUT = 100 mA,
VOUT = 0.8 V 30 µVRMS
SVR Supply voltage rejection
VOUT = 0.8V
VIN = 1.8V+/-VRIPPLE
VRIPPLE = 0.25V, freq. = 1kHz
IOUT = 10 mA
65
dB
VIN = 1.8V+/-VRIPPLE
VRIPPLE = 0.25V, freq.=10 kHz
IOUT = 100 mA
62
IQQuiescent current
IOUT = 0 mA 20
µA
IOUT= 0 mA, -40°C<TJ<125°C 50
IOUT = 0 to 500mA 100
IOUT=0 to 500mA, -
40°C<TJ<125°C 200
VIN input current in off mode:
VEN = GND(3) 0.001 1
PG Power Good output threshold
Rising edge 0.92*
VOUT V
Falling edge 0.8*
VOUT
Power Good output voltage low Isink=6mA open drain output 0.4 V
ISC Short-circuit current RL=0 600 800 mA
LD39050xx Electrical characteristics
7/24
VEN
Enable input logic low VIN=1.5 V to 5.5 V, 40°C<TJ<125°C 0.4 V
Enable input logic high VIN=1.5 V to 5.5 V, 40°C<TJ<125°C 0.9 V
IEN Enable pin input current VEN= VIN 0.1 100 nA
tON Turn on time (4) 30 µs
TSHDN
Thermal shutdown 160 °C
Hysteresis 20
COUT Output capacitor
Capacitance (see typical
performance characteristics for
stability)
122µF
1. All transient values are guaranteed by design, not production tested
2. Dropout voltage is the input-to-output voltage difference at which the output voltage is 100 mV below its nominal value. This
specification does not apply for output voltages below 1.5 V
3. PG pin floating
4. Turn-on time is time measured between the enable input just exceeding VEN high value and the output voltage just
reaching 95% of its nominal value
Table 6. Electrical characteristics for the LD39050PU (continued)
Symbol Parameter Test conditions Min. Typ. Max. Unit
Electrical characteristics LD39050xx
8/24
TJ = 25 °C, VIN = VOUT(NOM) + 1 V, CIN = COUT = 1 µF, IOUT = 10 mA, VEN = VIN, unless
otherwise specified.
Table 7. Electrical characteristics for the LD39050PUxx
Symbol Parameter Test conditions Min. Typ. Max. Unit
VIN Operating input voltage 1.5 5.5 V
VOUT VOUT accuracy
VOUT >1.5V, IOUT =10 mA,
TJ = 25°C -2.0 2.0
%
VOUT >1.5 V, IOUT = 10 mA,
-40°C<TJ<125°C -3.0 3.0
VOUT ≤ 1.5 V, IOUT = 10 mA ±20
mV
VOUT ≤ 1.5 V, IOUT =10 mA,
-40°C<TJ<125°C ±30
ΔVOUT Static line regulation VOUT +1 V ≤ VIN ≤ 5.5 V,
IOUT = 1 mA 0.01 %/V
ΔVOUT Transient line regulation (1) ΔVIN=500 mV, IOUT=10 mA, tR=5 µs 10 mVpp
ΔVIN=500 mV, IOUT=10 mA, tF=5 µs 10
ΔVOUT Static load regulation IOUT = 10 mA to 500 mA 0.002 %/mA
ΔVOUT Transient load regulation (1) IOUT = 10 mA to 500 mA, tR=5µs 40 mVpp
IOUT = 10 mA to 500 mA, tF=5µs 40
VDROP Dropout voltage (2) IOUT = 500mA, VOUT > 1.5 V
-40°C<TJ<125°C 200 400 mV
eNOutput noise voltage 10Hz to 100kHz, IO = 100 mA, 30 µVRMS
SVR Supply voltage rejection
VOUT = 1.5V
VIN = VOUT(NOM)+0.5V+/-VRIPPLE
VRIPPLE = 0.1V, freq. = 1kHz
IOUT = 10 mA
65
dB
VIN = VOUT(NOM)+0.5V+/-VRIPPLE
VRIPPLE = 0.1V, freq.=10 kHz
IOUT = 100 mA
62
IQQuiescent current
IOUT = 0 mA 20
µA
IOUT = 0 mA, -40°C<TJ<125°C 50
IOUT = 0 to 500mA 100
IOUT = 0 to 500mA -40°C<TJ<125°C 200
VIN input current in off mode:
VEN = GND (3) 0.001 1
PG
Power Good output threshold
Rising edge 0.92*
VOUT V
Falling edge 0.8*
VOUT
Power Good output voltage
low Isink=6mA open drain output 0.4 V
ISC Short-circuit current RL=0 600 800 mA
LD39050xx Electrical characteristics
9/24
VEN
Enable input logic low VIN=1.5 V to 5.5 V, -40°C<TJ<125°C 0.4 V
Enable input logic high VIN=1.5 V to 5.5 V, -40°C<TJ<125°C 0.9 V
IEN Enable pin input current VEN = VIN 0.1 100 nA
tON Turn on time (4) 30 µs
TSHDN
Thermal shutdown 160 °C
Hysteresis 20
COUT Output capacitor
Capacitance (see typical
performance characteristics for
stability)
122µF
1. All transient values are guaranteed by design, not production tested
2. Dropout voltage is the input-to-output voltage difference at which the output voltage is 100 mV below its nominal value. This
specification does not apply for output voltages below 1.5 V
3. PG pin floating
4. Turn-on time is time measured between the enable input just exceeding VEN high value and the output voltage just reaching
95 % of its nominal value
Table 7. Electrical characteristics for the LD39050PUxx (continued)
Symbol Parameter Test conditions Min. Typ. Max. Unit
Typical performance characteristics LD39050xx
10/24
5 Typical performance characteristics
Figure 4. VADJ accuracy Figure 5. VOUT accuracy
Figure 6. Dropout voltage vs. temperature Figure 7. Dropout voltage vs. temperature
0.75
0.76
0.77
0.78
0.79
0.8
0.81
0.82
0.83
0.84
0.85
-50 -25 0 25 50 75 100 125 150
T [°C]
V
ADJ
[V]
V
IN
= 1.8 V I
OUT
= 10 mA V
EN
= V
IN
0.75
0.76
0.77
0.78
0.79
0.8
0.81
0.82
0.83
0.84
0.85
-50 -25 0 25 50 75 100 125 150
T [°C]
V
ADJ
[V]
V
IN
= 1.8 V I
OUT
= 10 mA V
EN
= V
IN
2.45
2.46
2.47
2.48
2.49
2.5
2.51
2.52
2.53
2.54
2.55
-50 -25 0 25 50 75 100 125 150
T [°C]
V
OUT
[V]
V
IN
= 3.5 V I
OUT
= 10 mA V
EN
= V
IN
2.45
2.46
2.47
2.48
2.49
2.5
2.51
2.52
2.53
2.54
2.55
-50 -25 0 25 50 75 100 125 150
T [°C]
V
OUT
[V]
V
IN
= 3.5 V I
OUT
= 10 mA V
EN
= V
IN
0
50
100
150
200
250
300
350
-50 -25 0 25 50 75 100 125 150
T [°C]
Dropout [mV]
C
IN
= C
OUT
= 1 µF
V
EN
to V
IN
, I
OUT
= 500 mA, V
OUT
@ 1.5 V
0
50
100
150
200
250
300
350
-50 -25 0 25 50 75 100 125 150
T [°C]
Dropout [mV]
C
IN
= C
OUT
= 1 µF
V
EN
to V
IN
, I
OUT
= 500 mA, V
OUT
@ 1.5 V
0
50
100
150
200
250
300
350
-50 -25 0 25 50 75 100 125 150
T [°C]
Dropout [mV]
C
IN
= C
OUT
= 1 µF
V
EN
to V
IN
, I
OUT
= 500 mA, V
OUT
= 2.5 V
0
50
100
150
200
250
300
350
-50 -25 0 25 50 75 100 125 150
T [°C]
Dropout [mV]
C
IN
= C
OUT
= 1 µF
V
EN
to V
IN
, I
OUT
= 500 mA, V
OUT
= 2.5 V
Figure 8. Dropout voltage vs. output current Figure 9. Short-circuit current vs. dropout
voltage
0
0.025
0.05
0.075
0.1
0.125
0.15
0.175
0.2
0.225
0.25
0.275
0.3
0 100 200 300 400 500 600
IOUT [mA]
Dropout [V]
V
EN
to V
IN
, C
IN
= C
OUT
= 1 µF
0
0.025
0.05
0.075
0.1
0.125
0.15
0.175
0.2
0.225
0.25
0.275
0.3
0 100 200 300 400 500 600
IOUT [mA]
Dropout [V]
V
EN
to V
IN
, C
IN
= C
OUT
= 1 µF
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
0123456
V
DROP
[V]
I
SC
[A]
125 °C
85 °C
55 °C
25 °C
0 °C
-25 °C
-40 °C
V
IN
from 0 to 5.5 V, V
EN
= V
IN
, C
IN
= 1 µF, C
OUT
= 1 µF
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
0123456
V
DROP
[V]
I
SC
[A]
125 °C
85 °C
55 °C
25 °C
0 °C
-25 °C
-40 °C
V
IN
from 0 to 5.5 V, V
EN
= V
IN
, C
IN
= 1 µF, C
OUT
= 1 µF
LD39050xx Typical performance characteristics
11/24
Figure 10. Output voltage vs. input voltage Figure 11. Quiescent current vs. temperature
Figure 12. Quiescent current vs. temperature Figure 13. Quiescent current in off mode vs.
temperature
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
V
IN
[V]
V
OUT
[V]
125°C
85°C
55°C
25°C
0°C
- 25°C
- 40°C
VEN = VIN, CIN = COUT = 1 µF; IOUT = 500 mA
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
V
IN
[V]
V
OUT
[V]
125°C
85°C
55°C
25°C
0°C
- 25°C
- 40°C
VEN = VIN, CIN = COUT = 1 µF; IOUT = 500 mA
0
10
20
30
40
50
60
70
80
90
100
-50 -25 0 25 50 75 100 125 150
T [°C]
Iq [µA]
No load
I
OUT
= 0.5 A
V
IN
= 1.8 V, V
EN
to V
IN
, C
IN
= 1 µF C
OUT
= 1 µF, V
OUT
= 0.8 V
0
10
20
30
40
50
60
70
80
90
100
-50 -25 0 25 50 75 100 125 150
T [°C]
Iq [µA]
No load
I
OUT
= 0.5 A
V
IN
= 1.8 V, V
EN
to V
IN
, C
IN
= 1 µF C
OUT
= 1 µF, V
OUT
= 0.8 V
0
10
20
30
40
50
60
70
80
90
100
-50 -25 0 25 50 75 100 125 150
T [°C]
Iq [µA]
No load
IOUT = 0.5 A
VIN = 3.5 V, VEN to VIN, CIN = COUT = 1 µF, VOUT = 2.5 V
0
10
20
30
40
50
60
70
80
90
100
-50 -25 0 25 50 75 100 125 150
T [°C]
Iq [µA]
No load
IOUT = 0.5 A
VIN = 3.5 V, VEN to VIN, CIN = COUT = 1 µF, VOUT = 2.5 V
0
0.1
0.2
0.3
0.4
0.5
0.6
-50 -25 0 25 50 75 100 125 150
T [°C]
Iq [µA]
V
IN
= 3.5 V, V
OUT
= 2.5 V, V
EN
= GND, C
IN
= C
OUT
= 1 µF
0
0.1
0.2
0.3
0.4
0.5
0.6
-50 -25 0 25 50 75 100 125 150
T [°C]
Iq [µA]
V
IN
= 3.5 V, V
OUT
= 2.5 V, V
EN
= GND, C
IN
= C
OUT
= 1 µF
Figure 14. Load regulation Figure 15. Line regulation
-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
-50 -25 0 25 50 75 100 125 150
T [°C]
Load [%/mA]
V
IN
= 1.8 V, I
OUT
= from 10 mA to 500 mA, V
OUT
= 0.8 V, V
EN
= V
IN
-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
-50 -25 0 25 50 75 100 125 150
T [°C]
Load [%/mA]
V
IN
= 1.8 V, I
OUT
= from 10 mA to 500 mA, V
OUT
= 0.8 V, V
EN
= V
IN
-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
-50 -25 0 25 50 75 100 125 150
T [°C]
Line [%/V]
I
OUT
= 1 mA
I
OUT
= 100 mA
V
IN
= from 1.8 V to 5.5 V V
EN
= V
IN
V
OUT
= 0.8 V
-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
-50 -25 0 25 50 75 100 125 150
T [°C]
Line [%/V]
I
OUT
= 1 mA
I
OUT
= 100 mA
V
IN
= from 1.8 V to 5.5 V V
EN
= V
IN
V
OUT
= 0.8 V
Typical performance characteristics LD39050xx
12/24
Figure 16. Line regulation Figure 17. Supply voltage rejection vs.
temperature
Figure 18. Supply voltage rejection vs.
temperature
Figure 19. Supply voltage rejection vs.
temperature
-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
-50 -25 0 25 50 75 100 125 150
T [°C]
Line [%/V]
I
OUT
= 1 mA
I
OUT
= 100 mA
V
IN
= from 3.5 V to 5.5 V V
OUT
= 2.5 V V
EN
= V
IN
-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
-50 -25 0 25 50 75 100 125 150
T [°C]
Line [%/V]
I
OUT
= 1 mA
I
OUT
= 100 mA
V
IN
= from 3.5 V to 5.5 V V
OUT
= 2.5 V V
EN
= V
IN
0
10
20
30
40
50
60
70
80
90
100
-50 -25 0 25 50 75 100 125 150
T [°C]
SVR [dB]
C
IN
= C
OUT
= 1 µF
V
IN
from 1.7 V to 1.9 V, V
OUT
= 0.8 V, V
EN
to V
IN
, I
OUT
= 10 mA, freq. = 1 kHz
0
10
20
30
40
50
60
70
80
90
100
-50 -25 0 25 50 75 100 125 150
T [°C]
SVR [dB]
C
IN
= C
OUT
= 1 µF
V
IN
from 1.7 V to 1.9 V, V
OUT
= 0.8 V, V
EN
to V
IN
, I
OUT
= 10 mA, freq. = 1 kHz
0
10
20
30
40
50
60
70
80
90
100
-50 -25 0 25 50 75 100 125 150
T [°C]
SVR [dB]
C
IN
= C
OUT
= 1 µF
V
IN
from 1.7 V to 1.9 V, V
OUT
= 0.8 V, V
EN
to V
IN
, I
OUT
= 100 mA, freq. = 10 kHz
0
10
20
30
40
50
60
70
80
90
100
-50 -25 0 25 50 75 100 125 150
T [°C]
SVR [dB]
C
IN
= C
OUT
= 1 µF
V
IN
from 1.7 V to 1.9 V, V
OUT
= 0.8 V, V
EN
to V
IN
, I
OUT
= 100 mA, freq. = 10 kHz
0
10
20
30
40
50
60
70
80
90
100
-50 -25 0 25 50 75 100 125 150
T [°C]
SVR [dB]
CIN = COUT = 1 µF
VIN from 2.9 V to 3.1 V, VOUT = 2.5 V, VEN to VIN, IOUT = 10 mA, freq. = 1 kHz
0
10
20
30
40
50
60
70
80
90
100
-50 -25 0 25 50 75 100 125 150
T [°C]
SVR [dB]
CIN = COUT = 1 µF
VIN from 2.9 V to 3.1 V, VOUT = 2.5 V, VEN to VIN, IOUT = 10 mA, freq. = 1 kHz
Figure 20. Supply voltage rejection vs.
temperature
Figure 21. Supply voltage rejection vs.
frequency
0
10
20
30
40
50
60
70
80
90
100
-50 -25 0 25 50 75 100 125 150
T [°C]
SVR [dB]
CIN = COUT = 1 µF
VIN from 2.9 V to 3.1 V, VOUT = 2.5 V, VEN to VIN, IOUT = 100 mA, freq. = 10 kHz
0
10
20
30
40
50
60
70
80
90
100
-50 -25 0 25 50 75 100 125 150
T [°C]
SVR [dB]
CIN = COUT = 1 µF
VIN from 2.9 V to 3.1 V, VOUT = 2.5 V, VEN to VIN, IOUT = 100 mA, freq. = 10 kHz
0
10
20
30
40
50
60
70
80
90
100
0 102030405060708090100
Freq [kHz]
SVR [dB]
I
OUT
= 10 mA
I
OUT
= 100 mA
V
IN
from 1.7 V to 1.9 V, V
EN
to V
IN
, V
OUT
= 0.8 V, C
IN
= C
OUT
= 1 µF
0
10
20
30
40
50
60
70
80
90
100
0 102030405060708090100
Freq [kHz]
SVR [dB]
I
OUT
= 10 mA
I
OUT
= 100 mA
V
IN
from 1.7 V to 1.9 V, V
EN
to V
IN
, V
OUT
= 0.8 V, C
IN
= C
OUT
= 1 µF
LD39050xx Typical performance characteristics
13/24
Figure 22. Supply voltage rejection vs.
frequency
Figure 23. Noise output voltage vs. frequency
VIN = 1.8 V, VOUT = 0.8 V, VEN = 1 V, CIN = COUT = 1 µF,
TA = 25 °C
Figure 24. Enable voltage vs. temperature Figure 25. Enable voltage vs. temperature
0
10
20
30
40
50
60
70
80
90
100
0 102030405060708090100
Freq [kHz]
SVR [dB]
I
OUT
= 10 mA
I
OUT
= 100 mA
V
IN
from 2.9 V to 3.1 V, V
EN
to V
IN
, V
OUT
= 2.5 V, C
IN
= C
OUT
= 1 µF
0
10
20
30
40
50
60
70
80
90
100
0 102030405060708090100
Freq [kHz]
SVR [dB]
I
OUT
= 10 mA
I
OUT
= 100 mA
V
IN
from 2.9 V to 3.1 V, V
EN
to V
IN
, V
OUT
= 2.5 V, C
IN
= C
OUT
= 1 µF
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
1.E+01 1.E+02 1.E+03 1.E+04 1.E+05
f [Hz]
eN [uV/SQRT(Hz)]
A P - IOUT = 10 0 mA
A P - IOUT = 10 mA
A P - IOUT = 1m
A P - IOUT = 0 A
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
-50 -25 0 25 50 75 100 125 150
T [°C]
V
EN
[V]
High
Low
V
IN
= 3.5 V I
OUT
= 10 mA, V
OUT
= 2.5 V, C
IN
= C
OUT
= 1 µF
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
-50 -25 0 25 50 75 100 125 150
T [°C]
V
EN
[V]
High
Low
V
IN
= 3.5 V I
OUT
= 10 mA, V
OUT
= 2.5 V, C
IN
= C
OUT
= 1 µF
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
-50 -25 0 25 50 75 100 125 150
T [°C]
V
EN
[V]
High
Low
V
IN
= 5.5 V I
OUT
= 10 mA V
OUT
= 2.5 V, C
IN
= C
OUT
= 1 µF
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
-50 -25 0 25 50 75 100 125 150
T [°C]
V
EN
[V]
High
Low
V
IN
= 5.5 V I
OUT
= 10 mA V
OUT
= 2.5 V, C
IN
= C
OUT
= 1 µF
Figure 26. Load transient Figure 27. Load transient
VEN = VIN=1.8 V, IOUT = from10 mA to 0.5 A, CIN = COUT = 1
µF, VOUT = 0.8 V
VEN = VIN = 3.5V, IOUT from 10 mA to 0.5 A, VOUT = 2.5 V,
CIN = COUT = 1 µF
IOUT
VOUT
IOUT
VOUT
IOUT
VOUT
IOUT
VOUT
Typical performance characteristics LD39050xx
14/24
Figure 28. Load transient Figure 29. Line transient
VEN = VIN = 3.5 V, IOUT from 100 mA to 0.5 A, VOUT = 2.5 V,
CIN = COUT = 1 µF
VEN = VIN from 4.3 V to 4.8 V, IOUT = 10 mA, COUT = 1 µF,
CIN = NO
Figure 30. Startup transient Figure 31. Enable transient
VEN = VIN = from 0 V to 5.5 V, IOUT=10 mA, CIN = COUT = 1
µF, VOUT = 2.5 V
VEN from 0 V to 2 V, VIN = 3.5 V, VOUT = 2.5 V, IOUT = 10
mA, CIN = COUT = 1µF
IOUT
VOUT
IOUT
VOUT
VIN
VOUT
VIN
VOUT
VIN
VOUT
VIN
VOUT
VEN
VOUT
VEN
VOUT
Figure 32. ESR required for stability with
ceramic capacitors
Figure 33. ESR required for stability with
ceramic capacitors
VIN = VEN = from 1.8 V to 5.5 V, IOUT = from 1 mA to 500
mA, VOUT = 0.8 V, CIN = 1 µF
VIN = VEN = from 3.5 V to 5.5 V, IOUT = from 1 mA to 500
mA, VOUT = 2.5 V, CIN = 1 µF
0
0.25
0.5
0.75
1
1.25
1.5
12345678910111213141516171819202122
COUT [µF] (nominal value)
ESR @ 100 kHz [Ω]
UNSTABLE ZONE
STABLE ZONE
0
0.25
0.5
0.75
1
1.25
1.5
12345678910111213141516171819202122
COUT [µF] (nominal value)
ESR @ 100 kHz [Ω]
UNSTABLE ZONE
STABLE ZONE
0
0.25
0.5
0.75
1
1.25
1.5
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
COUT [µF] (nominal value)
ESR @ 100 kHz [Ω]
STABLE ZONE
UNSTABLE ZONE
0
0.25
0.5
0.75
1
1.25
1.5
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
COUT [µF] (nominal value)
ESR @ 100 kHz [Ω]
STABLE ZONE
UNSTABLE ZONE
LD39050xx Application information
15/24
6 Application information
The LD39050 is an ultra low dropout linear regulator. It provides up to 500 mA with a low
200 mV dropout. The input voltage range is from 1.5 V to 5.5 V. The device is available in
fixed and adjustable output versions.
The regulator is equipped with internal protection circuitry, such as short-circuit current
limiting and thermal protection.
The regulator is designed to be stable with ceramic capacitors on the input and the output.
The expected values of the input and output ceramic capacitors are from 1 µF to 22 µF with
1 µF typical. The input capacitor must be connected within 0.5 inches of the VIN terminal.
The output capacitor must also be connected within 0.5 inches of output pin. There is no
upper limit to the value of the input capacitor.
Figure 34 and Figure 35 illustrate the typical application schematics:
Figure 34. Application schematic for fixed version
VIN
GND
VIN
EN
OFF ON
CIN
PG
VOUT
VOUT
COUT
LD39050PUxx
NC
6
1
2
5
4
3
1µF 1µF
VIN
GND
VIN
EN
OFF ON
CIN
PG
VOUT
VOUT
COUT
LD39050PUxx
NC
6
1
2
5
4
3
1µF 1µF
Figure 35. Application schematic for adjustable version
VI
GND
V
EN
OFF ON
ADJ
PG
V
R1
R2
LD39050PU
6
1
2
5
4
3
VIN
IN
CIN
VOUT
OUT
COUT
1µF 1µF
VI
GND
V
EN
OFF ON
ADJ
PG
V
R1
R2
LD39050PU
6
1
2
5
4
3
VIN
IN
CIN
VOUT
OUT
COUT
1µF 1µF
Application information LD39050xx
16/24
For the adjustable version, the output voltage can be adjusted from 0.8 V up to the input
voltage minus the voltage drop across the PMOS (dropout voltage), by connecting a resistor
divider between the ADJ pin and the output, thus allowing remote voltage sensing.
The resistor divider should be selected using the following equation:
VOUT = VADJ (1 + R1 / R2) with VADJ = 0.8 V (typ.)
It is recommended to use resistors with values in the range of 10 kΩ to 50 kΩ. Lower values
can also be suitable, but will increase current consumption.
6.1 Power dissipation
An internal thermal feedback loop disables the output voltage if the die temperature rises to
approximately 160 °C. This feature protects the device from excessive temperature and
allows the user to push the limits of the power handling capability of a given circuit board
without risk of damaging the device.
It is very important to use a good PC board layout to maximize power dissipation. The
thermal path for the heat generated by the device is from the die to the copper lead frame
through the package leads and exposed pad to the PC board copper. The PC board copper
acts as a heat sink. The footprint copper pads should be as wide as possible to spread and
dissipate the heat to the surrounding ambient. Feed-through vias to inner or backside
copper layers are also useful in improving the overall thermal performance of the device.
The power dissipation of the device depends on the input voltage, output voltage and output
current, and is given by:
PD = (VIN -VOUT) IOUT
The junction temperature of the device is:
TJ_MAX = TA + RthJA x PD
where:
TJ_MAX is the maximum junction of the die,125 °C;
TA is the ambient temperature;
RthJA is the thermal resistance junction-to-ambient.
6.2 Enable function
The LD39050 features an enable function. When the EN voltage is higher than 2 V the
device is ON, and if it is lower than 0.8 V the device is OFF. In shutdown mode, consumption
is lower than 1 µA.
The EN pin does not have an internal pull-up, which means that it cannot be left floating if it
is not used.
6.3 Power Good function
Most applications require a flag showing that the output voltage is in the correct range.
The Power Good threshold depends on the adjust voltage. When the adjust is higher than
0.92*VADJ, the Power Good (PG) pin goes to high impedance. If the adjust is below
LD39050xx Application information
17/24
0.80*VADJ the PG pin goes to low impedance. If the device is functioning well, the Power
Good pin is at high impedance. If the output voltage is fixed using an external or internal
resistor divider, the Power Good threshold is 0.92*VOUT
.
The use of the Power Good function requires an external pull-up resistor, which must be
connected between the PG pin and VIN or VOUT
. The typical current capability of the PG pin
is up to 6 mA. The use of a pull-up resistor for PG in the range of 100 kΩ to 1 MΩ is
recommended. If the Power Good function is not used, the PG pin must remain floating.
Package mechanical data LD39050xx
18/24
7 Package mechanical data
In order to meet environmental requirements, ST offers these devices in different grades of
ECOPACK® packages, depending on their level of environmental compliance. ECOPACK®
specifications, grade definitions and product status are available at: www.st.com. ECOPACK
is an ST trademark.
LD39050xx Package mechanical data
19/24
Dim.
mm. inch.
Min. Typ. Max. Min. Typ. Max.
A0.800.90 1.00 0.031 0.035 0.039
A1 0 0.02 0.05 0 0.001 0.002
A30.20 0.008
b0.230.300.38 0.0090.012 0.015
D2.903.00 3.10 0.114 0.1180.122
D2 2.232.38 2.480.088 0.094 0.098
E2.903.00 3.10 0.114 0.1180.122
E2 1.50 1.65 1.75 0.0590.065 0.069
e0.950.037
L0.30 0.40 0.50 0.012 0.016 0.020
DFN6 (3x3 mm) mechanical data
7946637A
Package mechanical data LD39050xx
20/24
Dim.
mm. inch.
Min. Typ. Max. Min. Typ. Max.
A330 12.992
C 12.813.2 0.504 0.519
D 20.2 0.795
N60 2.362
T18.4 0.724
Ao 3.30.130
Bo 3.30.130
Ko 1.1 0.043
Po 4 0.157
P80.315
Tape & reel QFNxx/DFNxx (3x3) mechanical data
LD39050xx Package mechanical data
21/24
Figure 36. DFN6 (3x3) footprint recommended data
Different output voltage versions of the LD39050xx available on request LD39050xx
22/24
8 Different output voltage versions of the LD39050xx
available on request
Table 8. Options available on request
Order codes Output voltages
LD39050PU105R 1.05 V
LD39050PU15R 1.5 V
LD39050PU18R 1.8 V
LD39050xx Revision history
23/24
9 Revision history
Table 9. Document revision history
Date Revision Changes
11-Mar-2009 1 Initial release.
LD39050xx
24/24
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