Si91821
Vishay Siliconix
Micropower 300-mA CMOS LDO Regulator With Error Flag
FEATURES
D Input Voltage: 2.35−6.0 V
D Fixed 1.8-V, 2.5-V, 2.8-V, 3.0-V, 3.3-V, 5.0-V, or
Adjustable Output Voltage Options
D Low 120-mV Dropout at 300-mA Load
D Guaranteed 300-mA Output Current
D 500-mA Peak Output Current Capability
D Uses Low ESR Ceramic Output Capacitor
D Fast Load and Line Transient Response
D Only 100-mV(rms) Noise With Noise Bypass
Capacitor
Available
D 1-mA Maximum Shutdown Current
D Built-in Short Circuit and Thermal Protection
D Out-Of-Regulation Error Flag (Power_Good)
APPLICATIONS
D Cellular Phones
D Laptop and Palm Computers
D PDA, Digital Still Cameras
DESCRIPTION
The Si91821 is a 300-mA CMOS LDO (low dropout) voltage
regulator. The device features ultra low ground current and
dropout voltage to prolong battery life in portable electronics.
The Si91821 offers line and load transient response and ripple
rejection superior to that of bipolar or BiCMOS LDO regulators.
The device is designed to maintain regulation while delivering
500-mA peak current. This is useful for systems that have high
surge current upon turn-on. The Si91821 is designed to drive
the lower cost ceramic, as well as tantalum, output capacitors.
The device is guaranteed stable from maximum load current
down to 0-mA load. In addition, an external noise bypass
capacitor connected to the device’s CNOISE pin will lower the
LDO’s output noise for low noise applications.
The Si91821 also includes an out-of-regulation error flag.
When the output voltage is 5% below its nominal output
voltage, the error flag output goes low.
The Si91821 is available in both standard and lead (Pb)-free
MSOP-8 packages and is specified to operate over the
industrial temperature range of −40 _C to 85 _C.
TYPICAL APPLICATIONS CIRCUITS
7
VIN
SD
ERROR
2
VIN
VOUT
6
CNOISE
2.2 mF
GND
3
SET
GND
8
7
1, 4
VIN
VOUT
5
2.2 mF
SD
ERROR
2
VIN
VOUT
6
CNOISE
3
GND
2.2 mF
GND
Optional
Si91821
Figure 1.
1, 4
SET
VOUT
5
2.2 mF
Si91821
Fixed Output
Figure 2..
7
ON/OFF
VIN
2.2 mF
8
0.033 mF
GND
SD
ERROR
2
VIN
6
CNOISE
3
GND
VOUT
SET
8
1, 4
5
Adjustable Output
POWER_GOOD
1 MW
VOUT
2.2 mF
Si91821
Figure 3.
Document Number: 71614
S-51147–Rev. E, 20-Jun-05
Fixed Output, Low Noise, Full Features Application
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1
Si91821
Vishay Siliconix
ABSOLUTE MAXIMUM RATINGS
Input Voltage, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5 V
SD Input Voltage, VSD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 V to VIN
Output Current, IOUT . . . . . . . . . . . . . . . . . . . . . . . . . . Short Circuit Protected
Output Voltage, VOUT . . . . . . . . . . . . . . . . . . . . . . . . −0.3 V to VO(nom) + 0.3 V
Maximum Junction Temperature, TJ(max) . . . . . . . . . . . . . . . . . . . . . . . 150_C
Storage Temperature, TSTG . . . . . . . . . . . . . . . . . . . . . . . . . . −55_C to 150_C
ESD (Human Body Model) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 kV
Power Dissipation (Package)a
8-Pin MSOPb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 666 mW
Thermal Impedance (QJA)a
8-Pin MSOPb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185_C/W
Notes
a. Device mounted with all leads soldered or welded to PC board.
b. Derate 10 mW/_C above TA = 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.
RECOMMENDED OPERATING RANGE
Input Voltage, VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.35 V to 6 V
IOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to 300 mA
Output Voltage, VOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 to 5.0 V
Operating Ambient Temperature, TA . . . . . . . . . . . . . . . . . . . . −40_C to 85_C
SD Input Voltage, VSD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V to VIN
Operating Junction Temperature, TJ . . . . . . . . . . . . . . . . . . . −40_C to 125_C
CIN = 2.2 mF, COUT = 2.2 mF (ceramic, X5R or X7R type) , CNOISE = 0.033 mF (ceramic)
COUT Range = 1 mF to 10 mF ("10%, x5R or x7R type)
CIN w COUT
SPECIFICATIONS
Test Conditions
Unless Otherwise Specified
Parameter
Symbol
Input Voltage
VIN = VOUT(nom) + 1 V
V, IOUT = 1 mA
A
CIN = 2.2 mF, COUT = 2.2 mF, VSD = 1.5 V
Tempa
2.35
6.0
Full
1.5
5.0
Room
−1.5
1.5
Full
−2.5
2.5
Room
1.191
Full
1.179
1.251
From VIN = VOUT(nom) + 1 V
to VOUT(nom) + 2 V
Full
−0.18
0.18
From VIN = 5.5 V to 6 V
Full
−0.18
0.18
VOUT = 1.5 V From VIN = 2.5 V to 3.5 V
Full
−0.18
0.18
VOUT = 5 V From VIN = 5.5 V to 6 V
Full
−0.18
IOUT = 10 mA
Room
5
20
IOUT = 200 mA
Full
80
135
IOUT = 300 mA
Full
120
200
270
VIN
Output Voltage
VOUT
Adjustable Version
Output Voltage Accuracy
(to stated output voltage)
VOUT
1 mA v IOUT v 300 mA
Feedback Voltage (ADJ Version)
VSET
Line Regulation
(Except 5-V Version)
Line Regulation (5-V Version)
DVOUT
VIN
100
VOUT(nom)
Line Regulation (ADJ Version)
Dropout
p
Voltage
g d
Ground Pin Current
Shutdown Supply Current
Peak Output Current
Output Noise Voltage
Ripple
pp Rejection
j
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Limits
−40 to 85_C
VIN − VOUT
Minb
Typc
1.215
IOUT = 0 mA
Full
150
Room
500
IOUT = 300 mA
Room
600
IIN(off)
VSD = 0 V
Room
IO(peak)
VOUT w 0.95 x VOUT(nom), tpw = 2 ms
Room
eN
DVOUT/DVIN
0.1
500
V
%
VOUT(nom)
V
%/V
mV
mA
1
mA
w/o CNOISE
Room
260
CNOISE = 0.1 mF
Room
37
BW = 10 to 100 kHz
IOUT = 10 mA
CNOISE = 33 nF
Room
54
f = 1 kHz
Room
60
IOUT = 150 mA
f = 10 kHz
Room
50
f = 100 kHz
Room
40
BW = 10 Hz to 100 kHz
IOUT = 150 mA
1.239
Unit
0.18
IOUT = 200 mA
IGND
Maxb
mV (rms)
dB
Document Number: 71614
S-51147–Rev. E, 20-Jun-05
Si91821
Vishay Siliconix
SPECIFICATIONS
Test Conditions
Unless Otherwise Specified
Parameter
Symbol
VIN = VOUT(nom) + 1 V, IOUT = 1 mA
CIN = 2.2 mF, COUT = 2.2 mF, VSD = 1.5 V
Limits
−40 to 85_C
Tempa
Minb
Typc
Dynamic Line Regulation
DVO(line)
VIN : VOUT(nom) + 1 V to VOUT(nom) + 2 V
tr/tf = 5 ms, IOUT = 250 mA
Room
10
Dynamic Load Regulation
DVO(load)
IOUT : 1 mA to 150 mA, tr/tf = 2 ms
Room
30
Turn-on Overshoot
DVOOS
VIN followed by SD = High Event
CNOISE v 100 nF
Room
VOUT Turn-On-Time
tON
COUT = 10 mF, VOUT to 90% of final value,
VIN = 3.6 V
Room
350
Maxb
Unit
mV
2.5
%
mS
Thermal Shutdown
Thermal Shutdown Junction Temp
TJ(s/d)
Room
165
Thermal Hysteresis
THYST
Room
20
Short Circuit Current
ISC
VOUT = 0 V
Room
800
VIH
High = Regulator ON (Rising)
Full
VIL
Low = Regulator OFF (Falling)
Full
IIH
VSD = 0 V, Regulator OFF
Room
0.01
IIL
VSD = 6 V, Regulator ON
Room
1.0
Full
100
0.01
_C
mA
Shutdown Input
SD Input Voltage
SD Input Currente
Shutdown Hysteresis
VHYST
1.5
VIN
V
0.4
mA
mV
Error Output
Output High Leakage
IOFF
ERROR = VOUT(nom)
Full
Output Low Voltage
VOL
ISINK = 2 mA
Full
Power_Good Trip Threshold f, g
(Rising)
VTH
Hysteresis f
VHYST
Error Delay
tDELAY
Full
Room
CNOISE v 100 nF
Full
2
mA
0.4
0.93 x
VOUT
0.95 x
VOUT
0.97 x
VOUT
V
10
mS
2% x
VOUT
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 and are measured at TA = 25_C.
d. The dropout voltage is defined as VIN − VOUT when VOUT is 100 mV below the value of VOUT for VIN = VOUT + 2 V. This is applicable for voltages of 2.5 V or
higher.
e. The device’s shutdown pin includes a typical 6-MW internal pull-down resistor connected to ground.
f.
VOUT is defined as the output voltage of the DUT at 1 mA.
g. Typical only, from VOUT = 2.0 V to VOUT = 1.5 V.
Document Number: 71614
S-51147–Rev. E, 20-Jun-05
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Si91821
Vishay Siliconix
TIMING WAVEFORMS
VIH
SD
VIL
tON
VNOM = 0.95 VNOM
VOUT
tDELAY
ERROR
Figure 4.
tDELAY
Timing Diagram for Power-Up
PIN CONFIGURATION
MSOP-8
vOUT
1
8
ERROR
vIN
2
7
SD
GND
3
6
CNOISE
VOUT
4
5
SET
Top View
PIN DESCRIPTION
Pin Number
Name
1, 4
VOUT
2
VIN
3
GND
Ground pin. Local ground for CNOISE and COUT.
5
SET
For fixed output voltage versions, this pin could be connected to GND. For adjustable output voltage version, this
voltage feedback pin sets the output voltage via an external resistor divider.
6
CNOISE
7
SD
8
ERROR
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4
Function
Output voltage. Connect COUT between this pin and ground.
Input supply pin. Bypass this pin with a 2.2-mF ceramic or tantalum capacitor to ground.
Noise bypass pin. For low noise applications, a 0.01-mF or larger ceramic capacitor should be connected from this pin
to ground.
By applying less than 0.4 V to this pin, the device will be turned off. Connect this pin to VIN if unused.
This open drain output is an error flag output which goes low when VOUT drops 5% below its nominal voltage.
Document Number: 71614
S-51147–Rev. E, 20-Jun-05
Si91821
Vishay Siliconix
BLOCK DIAGRAM
Switches shown for device in normal operating mode (SD = HIGH)
5
SET
6
CNOISE
2
VIN
CIN
2.2 mF
7
SD
ON
+
−
RFB2
OFF
1, 4
60 mV
6 MW
RFB1
GND
To VIN
2 mA
+
+
−
1.215 V
VREF
3
−
ERROR
8
+
−
6
SET
REXT
+
Figure 5.
5
VOUT
COUT
2.2 mF
300-mA CMOS LDO Regulator
CNOISE
2
VIN
CIN
2.2 mF
R2
VSET
7
SD
R1
ON
+
−
OFF
To VIN
1, 4
60 mV
6 MW
2 mA
+
+
−
GND
3
1.215 V
VREF
Figure 6.
Document Number: 71614
S-51147–Rev. E, 20-Jun-05
+
−
VOUT
COUT
2.2 mF
REXT
−
8
ERROR
+
300-mA CMOS LDO Regulator (Adjustable Output)
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Si91821
Vishay Siliconix
DETAILED DESCRIPTION
The Si91821 is a low drop out, low quiescent current, and very
linear regulator with very fast transient response. It is primarily
designed for battery powered applications where battery run
time is at a premium. The low quiescent current allows
extended standby time while low drop out voltage enables the
system to fully utilize battery power before recharge. The
Si91821 is a very fast regulator with bandwidth exceeding
50 kHz while maintaining low quiescent current at light load
conditions. With this bandwidth, the Si91821 is the fastest
LDO available today. The Si91821 is stable with any output
capacitor type from 1 mF to 10.0 mF. However, X5R or X7R
ceramic capacitors are recommended for best output noise
and transient performance.
VIN
VIN is the input supply pin. The bypass capacitor for this pin
is not critical as long as the input supply has low enough source
impedance. For practical circuits, a 1.0-mF or larger ceramic
capacitor is recommended. When the source impedance is
not low enough and/or the source is several inches from the
Si91821, then a larger input bypass capacitor is needed. It is
required that the equivalent impedance (source impedance,
wire, and trace impedance in parallel with input bypass
capacitor impedance) must be smaller than the input
impedance of the Si91821 for stable operation. When the
source impedance, wire, and trace impedance are unknown,
it is recommended that an input bypass capacitor be used of
a value that is equal to or greater than the output capacitor.
VOUT
VOUT is the output voltage of the regulator. Connect a bypass
capacitor from VOUT to ground. The output capacitor can be
any value from 1.0 mF to 10.0 mF. A ceramic capacitor with
X5R or X7R dielectric type is recommended for best output
noise, line transient, and load transient performance.
SET
SET is not connected internally for the fixed voltage version.
Therefore, it can be connected to GND optionally. For the
adjustable output version, use a resistor divider R1 and R2,
connect R1 from VOUT to SET and R2 from SET to ground. R2
should be in the 25-kW to 150-kW range for low power
consumption, while maintaining adequate noise immunity.
The formula below calculates the value of R1, given the
desired output voltage and the R2 value.
R1 +
ǒVOUT * VSETǓR 2
(1)
VSET
VSET is nominally 1.215 V.
SHUTDOWN (SD)
SD controls the turning on and off of the Si91821. VOUT is
guaranteed to be on when the SD pin voltage equals or is
greater than 1.5 V. VOUT is guaranteed to be off when the SD
pin voltage equals or is less than 0.4 V. During shutdown
mode, the Si91821 will draw less than 2-mA current from the
source. To automatically turn on VOUT whenever the input is
applied, tie the SD pin to VIN.
ERROR
ERROR is an open drain output that goes low when VOUT is
less than 5% of its normal value. As with any open drain output,
an external pull up resistor is needed. This function is active
in shutdown.
The ERROR pin must be left opened if not used.
CNOISE
GND
Ground is the common ground connection for VIN and VOUT.
It is also the local ground connection for CNOISE, SET, and SD.
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For low noise application, connect a high frequency ceramic
capacitor from CNOISE to ground. A 0.01-mF or a 0.1-mF X5R
or X7R is recommended.
Document Number: 71614
S-51147–Rev. E, 20-Jun-05
Si91821
Vishay Siliconix
ORDERING INFORMATION
Standard
Part Number
Lead (Pb)-Free
Part Number
Marking
Voltage
1.80 V
Si91821DH-18-T1
Si91821DH-18-T1—E3
1821
1800
Si91821DH-25-T1
Si91821DH-25-T1—E3
1821
2500
2.50 V
Si91821DH-28-T1
Si91821DH-28-T1—E3
1821
2800
2.80 V
Si91821DH-30-T1
Si91821DH-30-T1—E3
1821
3000
3.00 V
Si91821DH-33-T1
Si91821DH-33-T1—E3
1821
3300
3.30 V
Si91821DH-50-T1
Si91821DH-50-T1—E3
1821
5000
5.00 V
Si91821DH-AD-T1
Si91821DH-AD-T1—E3
1821
ADJ
Adjustable
Temperature
Range
Package
−40 to 85_C
MSOP-8
Eval Kit
Temperature Range
Board Type
Si91821DB
−40 to 85_C
Surface Mount
TYPICAL CHARACTERISTICS (INTERNALLY REGULATED, 25_C UNLESS NOTED)
Dropout Voltage vs. Load Current
Dropout Characteristic
250
3.5
VOUT = 2.775 V
VOUT = 2.775 V
RLOAD = 16.5 W
3.0
200
150
V OUT (V)
V DROP (mV)
2.5
100
2.0
1.5
1.0
50
0.5
0
0.0
0
100
200
300
ILOAD (mA)
Document Number: 71614
S-51147–Rev. E, 20-Jun-05
400
500
0
1
2
3
4
5
6
VIN (V)
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Si91821
Vishay Siliconix
TYPICAL CHARACTERISTICS (INTERNALLY REGULATED, 25_C UNLESS NOTED)
Dropout Voltage vs. Temperature
180
Normalized Output Voltage vs. Load Current
0.30
IOUT = 300 mA
VOUT = 2.775 V
0.15
IOUT = 200 mA
V DROP (mV)
120
90
60
Output Voltage (%)
150
30
0.00
−0.15
−0.30
−0.45
−0.60
0
−50
IOUT = 10 mA
IOUT = 0 mA
−25
0
25
50
75
100
125
−0.75
150
0
50
100
Junction Temperature (_C)
Normalized VOUT vs. Temperature
0.6
300
350
−0.2
IOUT = 0 mA
−0.4
−0.6
−0.8
IOUT = 100 mA
−1.0
Dropout Voltage (mV)
140
−0.0
IOUT = 300 mA
−1.4
−1.6
−40
−20
0
20
40
60
80
100
120
120
IOUT = 300 mA
100
80
60
IOUT = 200 mA
40
−1.2
20
0
2.0
140
IOUT = 10 mA
2.5
3.0
Junction Temperature (_C)
200
1200
I GND ( mA)
1500
150
85_C
100
25_C
−40_C
1
2
3
5.0
IOUT = 300 mA
600
IOUT = 200 mA
4
Input Voltage (V)
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4.5
900
300
0
0
4.0
GND Pin Current vs. Temperature and Load
250
50
3.5
VOUT
No Load Current vs. Input Voltage
I GND ( mA)
250
160
0.2
8
200
Dropout Voltage vs. VOUT
180
0.4
V OUT (%)
150
Load Current (mA)
5
6
7
0
−40
IOUT = 0 mA
−20
0
20
40
60
80
100
120
140
Junction Temperature (_C)
Document Number: 71614
S-51147–Rev. E, 20-Jun-05
Si91821
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
5.00 ms/div
VOUT = 2.775 V
COUT = 2.2 mF
ILOAD = 1 to 150 mA
trise = 2 msec
5.00 ms/div
Load Transient Response-3
VOUT = 2.775 V
COUT = 2.2 mF
ILOAD = 150 to 1 mA
tfall = 2 msec
Load Transient Response-4
VOUT
10 mV/div
VOUT
10 mV/div
ILOAD
100 mA/div
ILOAD
100 mA/div
5.00 ms/div
VOUT = 2.775 V
COUT = 1.0 mF
ILOAD = 1 to 150 mA
trise = 2 msec
5.00 ms/div
LineTransient Response-1
VOUT = 2.775 V
COUT = 1.0 mF
ILOAD = 150 to 1 mA
tfall = 2 msec
LineTransient Respons-2
VOUT
2 V/div
VIN
2 V/div
VOUT
10 mV/div
20 ms/div
Document Number: 71614
S-51147–Rev. E, 20-Jun-05
VOUT
10 mV/div
VINSTEP = 4.77 to 5.77 V
VOUT = 2.775 V
COUT = 2.2 mF
CIN = 2.2 mF
ILOAD = 300 mA
trise = 5 msec
20 ms/div
VINSTEP = 5.77 to 4.77 V
VOUT = 2.775 V
COUT = 2.2 mF
CIN = 2.2 mF
ILOAD = 300 mA
tfall = 5 msec
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Si91821
Vishay Siliconix
TYPICAL WAVEFORMS
Turn-On Sequence
Turn-Off Sequence
VIN
CH-3 2 V/div
VIN 2 V/div
VOUT
CH-1 2 V/div
VOUT 2 V/div
ERROR 2 V/div
ERROR
CH-2 2 V/div
100 ms/div
20 ms/div
VIN = 4 V
VOUT = 2.775 V
CNOISE = 0.033 mF
ILOAD = 300 mA
Output Noise
VIN = 4 V
VOUT = 2.775 V
CNOISE = 0.033 mF
ILOAD = 300 mA
Noise Spectrum
20.0
mVń ǸHz
200 mV/div
0.01
10 ms/div
VIN = 3.80 V
VOUT = 2.775 V
IOUT = 300 mA
CNOISE = 0.033 mF
BW = 10 Hz to 1 MHz
10 Hz
VIN = 3.80 V
VOUT = 2.775 V/10 mA
CNOISE = 0.033 mF
1 MHz
Vishay Siliconix maintains worldwide manufacturing capability. Products may be manufactured at one of several qualified locations. Reliability data for Silicon Technology and
Package Reliability represent a composite of all qualified locations. For related documents such as package/tape drawings, part marking, and reliability data, see
http://www.vishay.com/ppg?71614.
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Document Number: 71614
S-51147–Rev. E, 20-Jun-05