Si91871
Vishay Siliconix
300-mA Ultra Low-Noise LDO Regulator
With Discharge Option
FEATURES
D
D
D
D
D
D
D
D
D
D
D
D
D
Ultra Low Dropout—300 mV at 300-mA Load
Ultra Low Noise—30
mV
RMS
(10-Hz to 100-kHz)
Shutdown Control
130-mA Ground Current at 300-mA Load
1.5% Guaranteed Output Voltage Accuracy
400-mA Peak Output Current Capability
Uses Low ESR Ceramic Capacitors
Fast Start-Up (50
ms)
Fast Line and Load Transient Response (v 30
ms)
1-mA Maximum Shutdown Current
Output Current Limit
Reverse Battery Protection
Built-in Short Circuit and Thermal Protection
D
Output, Auto-Discharge In Shutdown Mode
D
Fixed 1.2, 1.5, 1.8, 2.5, 2.6, 2.8, 3.0, 3.3, 5.0-V Output
Voltage Options
D
MLP33-5 PowerPAKr Package
Available
APPLICATIONS
D
Cellular Phones, Wireless Handsets
D
Noise-Sensitive Electronic Systems, Laptop and
Palmtop Computers
D
PDAs
D
Pagers
D
Digital Cameras
D
MP3 Player
D
Wireless Modem
DESCRIPTION
The Si91871 is a 300-mA CMOS LDO (low dropout) voltage
regulator. It is the perfect choice for low voltage, low power
applications. An ultra low ground current makes this part
attractive for battery operated power systems. The Si91871
also offers ultra low dropout voltage to prolong battery life in
portable electronics. Systems requiring a quiet voltage
source, such as RF applications, will benefit from the
Si91871’s ultra low output noise. An external noise bypass
capacitor connected to the device’s BP pin can further reduce
the noise level. The Si91871 is designed to maintain regulation
while delivering 400-mA peak current, making it ideal for
systems that have a high surge current upon turn-on.
For better transient response and regulation, an active
pull-down circuit is built into the Si91871 to clamp the output
voltage when it rises beyond normal regulation. The Si91871
automatically discharges the output voltage by connecting the
output to ground through a 100-W n-channel MOSFET when
the device is put in shutdown mode.
The Si91871 features reverse battery protection to limit
reverse current flow to approximately 1-mA in the event
reversed battery is applied at the input, thus preventing
damage to the IC.
The Si91871 is available in both the standard and
lead (Pb)-free 5-pin MLP33 PowerPAK packages and is
specified to operate over the industrial temperature range of
−40_C
to 85_.
TYPICAL APPLICATION CIRCUIT
Si91871
V
IN
2.2
mF
SD
SD
V
IN
V
OUT
V
OUT
2.2
mF
GND
BP
10 nF
MLP33-5
Document Number: 72012
S-50955—Rev. E, 16-May-05
www.vishay.com
1
Si91871
Vishay Siliconix
ABSOLUTE MAXIMUM RATINGS
Absolute Maximum Ratings
Input Voltage, V
IN
to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
−6.0
to 6.5 V
V
SD
(See Detailed Description) . . . . . . . . . . . . . . . . . . . . . . . . . .
−0.3
V to V
IN
Output Current, I
OUT
. . . . . . . . . . . . . . . . . . . . . . . . . . Short Circuit Protected
Output Voltage, V
OUT
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
−
0.3 V to V
IN
+ 0.3 V
Package Power Dissipation, (P
d
)
b
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 W
Thermal Resistance (q
JA
)
a
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55_C/W
R
(qJA)a
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8_C/W
Maximum Junction Temperature, T
J(max)
. . . . . . . . . . . . . . . . . . . . . . . 150_C
Storage Temperature, T
STG
. . . . . . . . . . . . . . . . . . . . . . . . . .
−65_C
to 150_C
Notes
a. Device mounted with all leads soldered or welded to PC board.
b. Derate 20 mW/_C above T
A
= 25_C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation
of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
Input Voltage, V
IN
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 V to 6 V
Input Voltage, V
SD
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V to V
IN
Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to 300 mA
C
IN
, C
OUTa
(Ceramic) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2
mF
C
EB
(Ceramic) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.01
mF
Operating Ambient Temperature, T
A
. . . . . . . . . . . . . . . . . . . .
−40_C
to 85_C
Operating Junction Temperature, T
J
. . . . . . . . . . . . . . . . . . .
−40_C
to 125_C
Notes
a. Maximum ESR of C
OUT:
0.2
W.
SPECIFICATIONS
Test Conditions Unless Specified
T
A
= 25_C, V
IN
= V
OUT(nom)
+ 1 V
(
)
I
OUT
= 1 mA, C
IN
= 2
mF,
C
OUT
= 2.0
mF
V
SD
= 1.5 V
Limits
−40
to 85_C
Parameter
Start-Up BP Current
Input Voltage Range
Symbol
I
OUT
V
IN
Temp
a
Room
Full
Min
b
Typ
c
1
Max
b
Unit
mA
ON/OFF = High
2
−2.0
−3.0
−2.5
−3.5
−0.06
0
0
1
45
50
300
65
400
100
130
110
150
400
1
1
1
1
6
2.0
3.0
2.5
3.5
0.18
0.3
0.4
V
V
OUT
w
1 8 V
1.8
Output Voltage Accuracy
1 mA
v
I
OUT
v
300 mA
V
OUT
= 1.2 V, 1.5 V
12V 15
Line Regulation (V
OUT
v
3 V)
Line Regulation
(3.0 V < V
OUT
v3.6
V)
Line Regulation (5-V Version)
DV
OUT
DV
IN
100
From V
IN
= V
OUT(nom)
+ 1 V to V
OUT(nom)
+ 2 V
V
OUT(nom)
From V
IN
= 5.5 V to 6 V
I
OUT
= 1 mA
Dropout
D
t
(V
OUT(nom)
w
2.6 V)
V
IN
−
V
OUT
Dropout
(V
OUT(
2.6 V
OUT(nom)
t
2 6 V, V
IN
w
)
2 V)
Voltage
d, g
d,
V lt
Voltage
d g
Room
Full
Room
Full
Full
Full
Full
Room
Room
Full
Room
Full
Room
Full
Room
Full
Room
Full
Room
Full
Room
Full
Room
Full
Full
%
%/V
I
OUT
= 50 mA
I
OUT
= 300 mA
I
OUT
= 50 mA
I
OUT
= 300 mA
I
OUT
= 0 mA
I
OUT
= 300 mA
I
GND
I
OUT
= 0 mA
I
OUT
= 300 mA
I
O(peak)
V
OUT
w
0.95 x V
OUT(nom)
. t
PW
= 2 ms
80
90
350
415
100
120
520
570
150
180
200
330
170
200
225
275
mA
mA
mV
Ground Pin Current
e, g
(V
OUT(nom)
v
3 V)
Ground Pin Current
e
(V
OUT(nom)
u
3 V)
Peak Output current
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2
Document Number: 72012
S-50955—Rev. E, 16-May-05
Si91871
Vishay Siliconix
SPECIFICATIONS
Test Conditions Unless Specified
T
A
= 25_C, V
IN
= V
OUT(nom)
+ 1 V
I
OUT
= 1 mA, C
IN
= 2
mF,
C
OUT
= 2.0
mF
V
SD
= 1.5 V
Limits
−40
to 85_C
Parameter
Symbol
Temp
a
Min
b
Typ
c
Max
b
Unit
Output Noise Voltage
e
N
V
NOM
= 2.6 V, BW = 10 Hz to 100 kHz,
0 mA
t
I
OUT
t
300 mA, C
NOISE
= 0.01
mF
f = 1 kHz
I
OUT
= 300 mA
f = 10 kHz
f = 100 kHz
Room
Room
Room
Room
Room
Room
Room
Room
30
60
40
30
20
20
150
20
1
700
mV(rms)
Ripple Rejection
pp
j
DV
OUT
/DV
IN
dB
Dynamic Line Regulation
Dynamic Load Regulation
Thermal Shutdown Junction
Temperature
Thermal Hysteresis
Reverse current
Short Circuit Current
DV
O(line)
DV
O(load)
T
J(S/D)
T
HYST
I
R
I
SC
V
IN
: V
OUT(nom)
+ 1 V to V
OUT(nom)
+ 2 V
t
r
/t
f
= 2
ms,
I
OUT
= 300 mA
I
OUT
: 1 mA to 300 mA, t
r
/t
f
= 2
ms
mV
_C
C
mA
mA
V
IN
=
−6.0
V
V
OUT
= 0 V
Room
Room
Shutdown
Shutdown Supply Current
SD Pin Input Voltage
Auto Discharge Resistance
SD Pin Input
Current
f
SD Hysteresis
V
OUT
Turn-On Time
I
CC(off)
V
SD
R_DIS
I
IN(SD)
V
HYST(SD)
t
ON
V
SD
(See Figure 1), I
LOAD
= 100 nA
V
SD
= 1.5 V, V
IN
= 6 V
V
SD
= 0 V
High = Regulator ON (Rising)
Low = Regulator OFF (Falling)
Room
Full
Full
Room
Room
Full
100
0.7
150
50
1.5
0.1
1
V
IN
0.4
mA
V
W
mA
mV
ms
Notes
a. Room = 25_C, Full =
−40
to 85_C.
b. The algebraic convention whereby the most negative value is a minimum and the most positive a maximum.
c. Typical values are for DESIGN AID ONLY, not guaranteed nor subject to production testing. Typical values for dropout voltage at V
OUT
w
2 V are measured at
V
OUT
= 3.3 V, while typical values for dropout voltage at V
OUT
< 2 V are measured at V
OUT
= 1.8 V.
d. Dropout voltage is defined as the input to output differential voltage at which the output voltage drops 2% below the output voltage measured with a 1-V
differential, provided that V
IN
does not not drop below 2.0 V.
e. Ground current is specified for normal operation as well as “drop-out” operation.
f.
The device’s shutdown pin includes a typical 2-MW internal pull-down resistor connected to ground.
g. V
OUT(nom)
is V
OUT
when measured with a 1-V differential to V
IN.
TIMING WAVEFORMS
V
IN
V
SD
t
r
v
1
ms
0V
t
ON
V
NOM
0.95 V
NOM
V
OUT
FIGURE 1.
Timing Diagram for Power-Up
Document Number: 72012
S-50955—Rev. E, 16-May-05
www.vishay.com
3
Si91871
Vishay Siliconix
PIN CONFIGURATION
MLP33-5 PowerPAK
SD
BP
V
IN
V
OUT
2
1
GND
GND
5
5
GND
GND
1
2
3
4
3
4
Top View
Bottom View
PIN DESCRIPTION
Pin Number
1
2
3
4
5
Name
SD
BP
V
IN
V
OUT
GND
Function
By applying less than 0.4 V to this pin, the device will be turned off. Connect this pin to V
IN
if unused
Noise bypass pin. For low noise applications, a 0.01
mF
ceramic capacitor should be connected from this pin to ground.
Input supply pin. Bypass this pin with a 1-mF ceramic or tantalum capacitor to ground
Output voltage. Connect C
OUT
between this pin and ground.
Ground pin. For better thermal capability, directly connected to large ground plane
ORDERING INFORMATION
Standard
Part Number
Si91871DMP-12-T1
Si91871DMP-15-T1
Si91871DMP-18-T1
Si91871DMP-25-T1
Si91871DMP-26-T1
Si91871DMP-28-T1
Si91871DMP-30-T1
Si91871DMP-33-T1
Si91871DMP-50-T1
Lead (Pb)-Free
Part Number
Si91871DMP-12-E3
Si91871DMP-15-E3
Si91871DMP-18-E3
Si91871DMP-25-E3
Si91871DMP-26-E3
Si91871DMP-28-E3
Si91871DMP-30-E3
Si91871DMP-33-E3
Si91871DMP-50-E3
Marking
7112
7115
7118
7125
7126
7128
7130
7133
7150
Voltage
1.2
1.5
1.8
2.5
2.6
2.8
3.0
3.3
5.0
Temp.
Range
Pkg.
−40
to 85_C
MLP33-5
www.vishay.com
4
Document Number: 72012
S-50955—Rev. E, 16-May-05
Si91871
Vishay Siliconix
TYPICAL CHARACTERISTICS (INTERNALLY REGULATED, 25_C UNLESS NOTED)
0.30
0.15
0.00
−0.15
−0.30
−0.45
−0.60
−0.75
0
50
100
150
200
250
300
Load Current (mA)
V
OUT
(%)
Normalized Output Voltage vs. Load Current
V
IN
= V
OUT(nom)
+ 1 V
0.4
0.2
Normalized V
OUT
vs. Temperature
V
IN
= V
OUT(nom)
+ 1 V
I
OUT
= 0 mA
Output Voltage (%)
−0.0
−0.2
−0.4
−0.6
−0.8
−1.0
−40
I
OUT
= 75 mA
I
OUT
= 150 mA
I
OUT
= 300 mA
−15
10
35
60
85
Ambient Temperature (_C)
150
GND Current vs. Load Current
V
OUT
= 3.0 V
V
IN
= 4.0 V
85_C
300
250
No Load GND Pin Current vs. Input Voltage
125
25_C
I
GND
(
mA)
I
GND
(
mA)
100
200
150
100
75
50
50
0
50
100
150
200
250
300
Load Current (mA)
0
2
3
4
5
6
7
Input Voltage (V)
−40_C
85_C
25_C
−40_C
0
Power Supply Rejection
C
IN
= 1
mF
C
OUT
= 1
mF
I
LOAD
= 150 mA
V
OUT
= 3.0 V
I
SC
(mA)
750
725
700
Output Short Circuit Current vs. Temperature
V
OUT
= 2.6 V
−20
Gain (dB)
−40
675
650
−60
625
−80
10
600
−40
100
1000
10000
100000
1000000
−15
10
35
60
85
Frequency (Hz)
Document Number: 72012
S-50955—Rev. E, 16-May-05
AmbientTemperature (_C)
www.vishay.com
5
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