Si91872
Vishay Siliconix
300-mA Low-Noise LDO Regulator
With Error Flag and Discharge Option
FEATURES
D
D
D
D
D
D
D
D
D
D
D
D
D
D
Ultra Low Dropout—300 mV at 300-mA Load
Low Noise—75 mVRMS (10-Hz to 100-kHz)
Out-of-Regulation Error Flag (power good)
Shutdown Control
130-mA Ground Current at 300-mA Load
Fast Start-Up (50 mS)
1.5% Guaranteed Output Voltage Accuracy
400-mA Peak Output Current Capability
Uses Low ESR Ceramic Capacitors
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, 1.8, 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 Si91872 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 and ultra fast turn-on
make this part attractive for battery operated power systems.
The Si91872 also offers ultra low dropout voltage to prolong
battery life in portable electronics. Systems requiring a quiet
voltage source will benefit from the Si91872’s low output noise.
The Si91872 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.
voltage when it rises beyond normal regulation. The Si91872
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 Si91872 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 Si91872 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_.
For better transient response and regulation, an active
pull-down circuit is built into the Si91872 to clamp the output
TYPICAL APPLICATION CIRCUIT
Si91872
VIN
VIN
VOUT
VOUT
2.2 mF
SD
2.2 mF
51 kW
SD
GND
ERROR
ERROR
MLP33-5
Document Number: 72013
S-51147—Rev. F, 20-Jun-05
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1
Si91872
Vishay Siliconix
ABSOLUTE MAXIMUM RATINGS
Thermal Resistance (qJA)a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55_C/W
R(qJA)a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8_C/W
Absolute Maximum Ratings
Input Voltage, VIN to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −6.0 to 6.5 V
Maximum Junction Temperature, TJ(max) . . . . . . . . . . . . . . . . . . . . . . . 150_C
VERROR, VSD (See Detailed Description) . . . . . . . . . . . . . . . . . . −0.3 V to VIN
Storage Temperature, TSTG . . . . . . . . . . . . . . . . . . . . . . . . . . −65_C to 150_C
Notes
a. Device mounted with all leads soldered or welded to PC board.
b. Derate 20 mW/_C above TA = 25_C
Output Current, IOUT . . . . . . . . . . . . . . . . . . . . . . . . . . Short Circuit Protected
Output Voltage, VOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 V to VIN + 0.3 V
Package Power Dissipation, (Pd)b . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 W
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.
RECOMMENDED OPERATING RANGE
Input Voltage, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 V to 6 V
Operating Ambient Temperature, TA . . . . . . . . . . . . . . . . . . . . −40_C to 85_C
Input Voltage, VSD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V to VIN
Operating Junction Temperature, TJ . . . . . . . . . . . . . . . . . . . −40_C to 125_C
Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to 300 mA
Notes
a. Maximum ESR of COUT: 0.2 W.
CIN, COUTa (Ceramic) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 mF
SPECIFICATIONS
Limits
Test Conditions Unless Specified
Parameter
Symbol
Input Voltage Range
TA = 25_C, VIN = VOUT(nom) + 1 V, IOUT = 1 mA,
CIN = 2 mF, COUT = 2.0 mF, VSD = 1.5 V
VIN
VOUT w 1.8
18V
Output Voltage Accuracy
DVIN
VIN − VOUT
Output Noise Voltage
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2
2.0
Full
−3.5
1
3.5
Full
−0.06
0.18
Full
0
0.3
From VIN = 5.5 V to 6 V
Full
0
0.4
IOUT = 1 mA
Room
1
Room
45
Full
50
90
Room
300
350
From VIN = VOUT(nom) + 1 V to VOUT(nom) + 2 V
IOUT = 300 mA
IOUT = 300 mA
IGND
Peak Output current
1
2.5
IOUT = 0 mA
IOUT = 0 mA
Ground Pin Currente, g
(VOUT(nom)
(
) u 3 V)
V
2
−2.0
3.0
IOUT = 300 mA
Ground Pin Currente, g
(VOUT(nom)
(
) v 3 V)
6
Full
Room
1
IOUT = 50 mA
Dropout Voltaged, g
(VOUT(nom)
(
) t 2.6 V, VIN w 2 V)
Unit
1
IOUT = 50 mA
d g
d,
Dropoutt V
D
Voltage
lt
(VOUT(nom) w 2.6 V)
Maxb
−2.5
VOUT(nom)
(
)
Line Regulation (5-V Version)
Typc
−3.0
Line Regulation (VOUT v 3 V)
Line Regulation
(3.0 V < VOUT v3.6 V)
Minb
Full
VOUT = 1.2
1 2 V,
V 1.5
15V
100
Tempa
Room
1 mA v IOUT v 300 mA
DVOUT
−40 to 85_C
IOUT = 300 mA
Full
65
Full
400
Full
100
Full
130
Full
110
Full
150
Full
Room
170
mA
200
Room
eN
200
330
Room
VOUT = 2.6 V, BW = 10 Hz to 100 kHz,
0 mA t IOUT t 150 mA
150
180
Room
Full
520
570
Room
VOUT w 0.95 x VOUT(nom). tPW = 2 ms
mV
100
120
Room
IO(peak)
%/V
80
415
Room
%
225
275
400
mA
75
mV(rms)
Document Number: 72013
S-51147—Rev. F, 20-Jun-05
Si91872
Vishay Siliconix
SPECIFICATIONS
Limits
Test Conditions Unless Specified
Parameter
Ripple
pp Rejection
j
TA = 25_C, VIN = VOUT(nom) + 1 V, IOUT = 1 mA,
CIN = 2 mF, COUT = 2.0 mF, VSD = 1.5 V
Symbol
DVOUT/DVIN
IOUT = 300 mA
−40 to 85_C
Tempa
Minb
Typc
f = 1 kHz
Room
60
f = 10 kHz
Room
40
f = 100 kHz
Room
30
Dynamic Line Regulation
DVO(line)
VIN : VOUT(nom) + 1 V to VOUT(nom) + 2 V
tr/tf = 2 ms, IOUT = 300 mA
Room
20
Dynamic Load Regulation
DVO(load)
IOUT : 1 mA to 300 mA, tr/tf = 2 ms
Room
25
Thermal Shutdown Junction
Temperature
TJ(S/D)
Room
150
Thermal Hysteresis
THYST
Room
20
Maxb
Unit
dB
mV
_C
C
Reverse current
IR
VIN = −6.0 V
Room
1
mA
Short Circuit Current
ISC
VOUT = 0 V
Room
700
mA
Shutdown
Shutdown Supply Current
SD Pin Input Voltage
ICC(off)
VSD
VSD = 0 V
Room
High = Regulator ON (Rising)
Full
Low = Regulator OFF (Falling)
Full
0.1
1.5
1
VIN
0.4
mA
V
Auto Discharge Resistance
R_DIS
Si91872 Only
Room
100
W
SD Pin Input Currentf
IIN(SD)
VSD = 1.5 V, VIN = 6 V
Room
0.7
mA
Full
150
mV
tON
VSD (See Figure 1), ILOAD = 100 mA
Room
50
ms
ERROR High Leakage
IOFF
ERROR v VIN. VOUT in Regulation
Full
1
mA
ERROR Low Voltage
VOL
ISINK = 0.5 mA
Full
0.4
V
VERROR
VOUT Below VOUT(nom)g, VIN w 2 V
VOUT Falling, IOUT = 1 mA, VOUT(nom) w 2 V
Full
VOUT(nom)g t 2 V, VIN u 2 V
Full
−4
Room
1.5
SD Hysteresis
VOUT Turn-On Time
VHYST(SD)
ERROR Output
ERROR Voltage Threshold
ERROR Voltage Threshold
Hysteresis
VHYST(ERROR)
−2
−4
−6
%
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.
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 VIN 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. VOUT(nom) is VOUT when measured with a 1-V differential to VIN.
TIMING WAVEFORMS
VIN
VSD
0V
tr v 1 mS
tON
VNOM
0.95 VNOM
VOUT
FIGURE 1. Timing Diagram for Power-Up
Document Number: 72013
S-51147—Rev. F, 20-Jun-05
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Si91872
Vishay Siliconix
PIN CONFIGURATION: MLP33-5
MLP33-5 PowerPAK
SD
ERROR
GND
1
2
1
2
GND
5
5
VIN
3
GND
3
VOUT
4
GND
4
Top View
Bottom View
PIN DESCRIPTION
Pin Number
Name
Function
1
SD
2
ERROR
By applying less than 0.4 V to this pin, the device will be turned off. Connect this pin to VIN if unused
3
VIN
4
VOUT
Output voltage. Connect COUT between this pin and ground.
5
GND
Ground pin. For better thermal capability, directly connected to large ground plane
The open drain output is an error flag output which goes low when VOUT drops 4% below its nominal voltage.
Input supply pin. Bypass this pin with a 1-mF ceramic or tantalum capacitor to ground
ORDERING INFORMATION
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Standard
Part Number
Lead (Pb)-Free
Part Number
Marking
Voltage
Si91872DMP-12-T1
Si91872DMP-12-E3
7212
1.2
Si91872DMP-18-T1
Si91872DMP-18-E3
7218
1.8
Si91872DMP-25-T1
Si91872DMP-25-E3
7225
2.5
Si91872DMP-26-T1
Si91872DMP-26-E3
7226
2.6
Si91872DMP-28-T1
Si91872DMP-28-E3
7228
2.8
Si91872DMP-30-T1
Si91872DMP-30-E3
7230
3.0
Si91872DMP-33-T1
Si91872DMP-33-E3
7233
3.3
Si91872DMP-50-T1
Si91872DMP-50-E3
7250
5.0
Temp.
Range
Pkg.
−40
40 to 85_C
MLP33 5
MLP33-5
Document Number: 72013
S-51147—Rev. F, 20-Jun-05
Si91872
Vishay Siliconix
TYPICAL CHARACTERISTICS (INTERNALLY REGULATED, 25_C UNLESS NOTED)
Normalized Output Voltage vs. Load Current
0.30
VIN = VOUT(nom) + 1 V
VIN = VOUT(nom) + 1 V
0.15
Normalized VOUT vs. Temperature
0.4
0.2
−0.0
V OUT (%)
Output Voltage (%)
IOUT = 0 mA
0.00
−0.15
−0.30
−0.2
−0.6
−0.60
−0.8
0
50
100
150
200
250
IOUT = 150 mA
−0.4
−0.45
−0.75
IOUT = 75 mA
IOUT = 300 mA
−1.0
−40
300
−15
Load Current (mA)
GND Current vs. Load Current
150
10
35
60
85
Ambient Temperature (_C)
VOUT = 3.0 V
VIN = 4.0 V
No Load GND Pin Current vs. Input Voltage
300
85_C
250
125
200
100
I GND ( mA)
I GND ( mA)
25_C
−40_C
150
85_C
25_C
100
−40_C
75
50
50
0
0
50
100
150
200
250
300
2
3
Load Current (mA)
Power Supply Rejection
0
−20
4
5
6
7
Input Voltage (V)
750
Output Short Circuit Current vs. Temperature
VOUT = 2.6 V
CIN = 1 mF
COUT = 1 mF
ILOAD = 150 mA
VOUT = 3.0 V
725
I SC (mA)
Gain (dB)
700
−40
675
650
−60
625
−80
10
100
1000
10000
Frequency (Hz)
Document Number: 72013
S-51147—Rev. F, 20-Jun-05
100000
1000000
600
−40
−15
10
35
60
85
AmbientTemperature (_C)
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Si91872
Vishay Siliconix
TYPICAL CHARACTERISTICS (INTERNALLY REGULATED, 25_C UNLESS NOTED)
Dropout Voltage vs. Load Current
350
VOUT = 3.0 V
300
VOUT = 3.0 V
2.5
250
2.0
V OUT (V)
V DROP (mV)
VIN − VOUT Transfer Characteristic
3.0
200
150
1.5
1.0
100
0.5
50
0
0.0
0
60
120
180
240
0
300
1
2
3
ILOAD (mA)
350
Dropout Voltage vs. Temperature
Dropout Voltage (mV)
V DROP (mV)
250
200
IOUT = 150 mA
100
6
250
200
150
IOUT = 150 mA
IOUT = 75 mA
50
IOUT = 10 mA
IOUT = 0 mA
−25
0
25
50
75
100
Junction Temperature (_C)
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IOUT = 300 mA
300
100
IOUT = 75 mA
50
0
−50
6
350
IOUT = 300 mA
150
5
Dropout Voltage vs. VOUT
400
VOUT = 3.0 V
300
4
VIN (V)
125
150
0
1.0
IOUT = 10 mA
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
VOUT
Document Number: 72013
S-51147—Rev. F, 20-Jun-05
Si91872
Vishay Siliconix
TYPICAL WAVEFORMS
Load Transient Response-1
Load Transient Response-2
VOUT
10 mV/div
VOUT
10 mV/div
ILOAD
100 mA/div
ILOAD
100 mA/div
20 ms/div
20 ms/div
VOUT = 3.0 V
COUT = 1 mF
ILOAD = 1 to 150 mA
trise = 2 msec
VOUT = 3.0 V
COUT = 1 mF
ILOAD = 150 to 1 mA
tfall = 2 msec
LineTransient Response-1
LineTransient Respons-2
VOUT
10 mV/div
VOUT
10 mV/div
VIN
2 V/div
VIN
2 V/div
20 ms/div
20 ms/div
VINSTEP = 4 to 5 V
VOUT = 3 V
COUT = 1 mF
CIN = 1 mF
ILOAD = 150 mA
trise = 5 msec
Document Number: 72013
S-51147—Rev. F, 20-Jun-05
VINSTEP = 5 to 4 V
VOUT = 3 V
COUT = 1 mF
CIN = 1 mF
ILOAD = 150 mA
tfall = 5 msec
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Si91872
Vishay Siliconix
TYPICAL WAVEFORMS
Output Noise
Noise Spectrum
Output Spectral Noise Density
10
VOUT
200 mV/div
mVń ǸHz
0.01
4 ms/div
10 Hz
VIN = 4 V
VOUT = 3 V
IOUT = 150 mA
BW = 10 Hz to 100 kHz
1 MHz
VIN = 4 V
VOUT = 3 V
ILOAD = 150 mA
FUNCTIONAL BLOCK DIAGRAM
Si91872
VIN
Reverse Polarity
Protection
Reference
−
+
VOUT
Thermal
Sensor
Current
Limit
ERROR
SD
Shutdown
Control
GND
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Document Number: 72013
S-51147—Rev. F, 20-Jun-05
Si91872
Vishay Siliconix
DETAILED DESCRIPTION
The Si91872 is a low-noise, low drop-out and low quiescent
current linear voltage regulator, packaged in a small footprint
MLP33-5 package. The Si91872 can supply loads up to
300 mA. As shown in the block diagram, the circuit consists of
a bandgap reference, error amplifier, p-channel pass transistor
and feedback resistor string. Additional blocks, not shown in
the block diagram, include a precise current limiter, reverse
battery and current protection, and thermal sensor.
Thermal Overload Protection
The thermal overload protection limits the total power
dissipation and protects the device from being damaged.
When the junction temperature exceeds 150_C, the device
turns the p-channel pass transistor off.
Reverse Battery Protection
The Si91872 has a battery reverse protection circuitry that
disconnects the internal circuitry when VIN drops below the
GND voltage. There is no current drawn in such an event.
When the SD pin is hardwired to VIN, the user must connect
the SD pin to VIN via a 100-kW resistor if reverse battery
protection is desired. Hardwiring the SD pin directly to the VIN
pin is allowed when reverse battery protection is not desired.
ERROR
ERROR is an open drain output that goes low when VOUT is
less than 4% of its normal value. To obtain a logic level output,
connect a pull-up resister from ERROR to VOUT or any other
voltage equal to or less than VIN. ERROR pin is high
impedance (off) when SD pin is low.
package and the circuit board, and the ambient temperature.
The power dissipation is defined as
PD = (VIN – VOUT) * IOUT .
Junction temperature is defined as
TJ = TA + ((PD * (RθJC + RθCA)).
To calculate the limits of performance, these equations must
be rewritten.
Allowable power dissipation is calculated using the equation
PD = (TJ − TA )/ (RθJC + RθCA)
While allowable output current is calculated using the equation
IOUT = (TJ − TA )/ (RθJC + RθCA) * (VIN – VOUT).
Ratings of the Si91872 that must be observed are
TJmax = 125 _C, TAmax = 85 _C, (VIN – VOUT)max = 5.3 V,
RθJC = 8 _C/W.
The value of RθCA is dependent on the PC board used. The
value of RθCA for the board used in device characterization is
approximately 46 _C/W.
Figure 1 shows the performance limits graphically for the
Si91872 mounted on the circuit board used for thermal
characterization.
Auto-Discharge
VOUT has an internal 100-W (typ.) discharge path to ground
when SD pin is low for the Si91872.
0.35
Stability
0.25
Safe Operating Area
The ability of the Si91872 to supply current is ultimately
dependent on the junction temperature of the pass device.
Junction temperature is in turn dependent on power
dissipation in the pass device, the thermal resistance of the
I OUT (A)
The circuit is stable with only a small output capacitor equal to
6 nF/mA (= 2 mF @ 300 mA). Since the bandwidth of the error
amplifier is around 1−3 MHz and the dominant pole is at the
output node, the capacitor should be capacitive in this range,
i.e., for 150-mA load current, an ESR
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