MICREL MIC5271

MIC5271
Micrel
MIC5271
µCap Negative Low-Dropout Regulator
General Description
Features
The MIC5271 is a µCap 100mA negative regulator in a
SOT-23-5 package. With better than 2% initial accuracy, this
regulator provides a very accurate supply voltage for applications that require a negative rail. The MIC5271 sinks 100mA
of output current at very low dropout voltage (600mV maximum at 100mA of output current).
The µCap regulator design is optimized to work with lowvalue, low-cost ceramic capacitors. The output typically requires only a 1µF capacitance for stability.
Designed for applications where small packaging and efficiency are critical, the MIC5271 combines LDO design expertise with IttyBitty packaging to improve performance and
reduce power dissipation. Ground current is optimized to help
improve battery life in portable applications. The MIC5271
also includes a TTL-compatible enable pin, allowing the user
to put the part into a zero-current off-mode.
The MIC5271 is available in the SOT-23-5 package for space
saving applications and it is available with an adjustable
output.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
•
•
•
•
•
•
•
•
•
•
Stable with ceramic or tantalum capacitor
Positive and negative enable thresholds
Low dropout voltage: 500mV @ 100mA
Low ground current: 35µA @ load = 100µA
Tight initial accuracy: ±2%
Tight load and line regulation
Thermal shutdown
Current limiting
IttyBitty SOT-23-5 packaging
Zero-current off-mode
Applications
•
•
•
•
•
GaAsFET bias
Portable cameras and video recorders
PDAs
Battery-powered equipment
Post-regulation of DC-DC converters
Ordering Information
Part Number
Marking
Voltage*
Junction Temp. Range
Package
MIC5271BM5
L9AA
MIC5271-3.0BM5
L930
Adj.
–40°C to +125°C
SOT-23-5
–3.0V
–40°C to +125°C
SOT-23-5
MIC5271-5.0BM5
L950
–5.0V
–40°C to +125°C
SOT-23-5
* For other voltage options, please contact Micrel Marketing.
Typical Application
Enable Input
MIC5271BM5
2
1
VIN
–6.0V
5
GND ADJ
1µF
R1
3
R2
EN
–IN
ENABLE VOLTAGE (V)
5
4
–OUT
4
VOUT
–5.0V
10µF
3
2
1
0
Regulator On
Regulator Off
-1
-2
-3
-4
-5
-3
Regulator On
-5 -7 -9 -11 -13 -15
SUPPLY VOLTAGE (V)
Regulator With Adjustable Output
IttyBitty is a registered trademark of Micrel, Inc.
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
October 2003
1
MIC5271
MIC5271
Micrel
Pin Configuration
ADJ GND EN
3
2
1
L9AA
4
5
–OUT
–IN
MIC5271BM5
Adjustable Output Voltage
Pin Description
Pin Number
(Adj.)
Pin Name
1
EN
2
GND
Ground.
3
ADJ
Adjustable (Input): Adjustable feedback output connects to resistor voltage
divider.
4
–OUT
5
–IN
MIC5271
Pin Function
Enable Input. TTL logic compatible enable input. Logic High = ON, Logic
Low or open = OFF.
Negative Regulator Output.
Negative Supply Input.
2
October 2003
MIC5271
Micrel
Absolute Maximum Ratings (Note 1)
Operating Ratings (Note 2)
Input Voltage (V–IN) ...................................... –20V to +0.3V
Enable Voltage (VEN) .................................... –20V to +20V
Power Dissipation (PD) ............................ Internally Limited
Junction Temperature (TJ) ....................... –40°C to +125°C
Lead Temperature (soldering, 5 sec.) ....................... 260°C
Storage Temperature (TS) ....................... –65°C to +150°C
ESD Rating, Note 3
Input Voltage (VIN) ....................................... –16V to –3.3V
Enable Voltage (VEN) .................................... –16V to +16V
Junction Temperature (TJ) ....................... –40°C to +125°C
Thermal Resistance (θJA) Note 4 ......................... 235°C/W
Electrical Characteristics (Note 5)
VIN = VOUT – 1.0V; COUT = 4.7µF, IOUT = 100µA; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C; unless noted.
Symbol
Parameter
Condition
VOUT
Output Voltage Accuracy
Variation from nominal VOUT
∆VOUT/∆T
Output Voltage Temperature
Coefficient
Note 6
100
∆VOUT/VOUT
Line Regulation
VIN = VOUT – 1V to –16V
0.04
0.15
0.2
%/V
∆VOUT/VOUT
Load Regulation
IOUT = 100µA to 100mA, Note 7
0.4
1.8
2.0
%
%
VIN – VOUT
Dropout Voltage, Note 8
IOUT = 100µA
55
IOUT = 50mA
360
500
mV
IOUT = 100mA
500
700
900
mV
IOUT = 100µA
25
100
µA
IOUT = 50mA
0.9
IOUT = 100mA
2.0
3.0
mA
0.1
+1.0
µA
IGND
Ground Current, Note 9
Min
Typ
–2
–3
IGND_SD
Ground current in shutdown
VEN = ±0.6V
–1.0
PSRR
Ripple Rejection
f = 120Hz
50
ILIMIT
Current Limit
VOUT = 0V
235
TON
Turn-on Time
Time to VOUT = 90% nom.
60
VEN
Input Low voltage
Regulator OFF
Input High Voltage
Regulator ON
Enable Input Current
VEN = ± 0.6V and –2.0V
VEN = +2.0V
Max
Units
2
3
%
%
ppm/°C
mV
mA
dB
350
mA
Enable Input
IEN
µs
V
±0.6
V
±2.0
5.6
0.1
10.0
µA
Note 1.
Exceeding the absolute maximum rating may damage the device.
Note 2.
The device is not guaranteed to function outside its operating rating.
Note 3.
Devices are ESD sensitive. Handling precautions recommended.
Note 4.
The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(max), the junction-to-ambient thermal
resistance, θJA, and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using:
PD(max) = (TJ(max) – TA) / θJA, where θJA is 235°C/W. Exceeding the maximum allowable power dissipation will result in excessive die
temperature, and the regulator will go into thermal shutdown. See the “Thermal Considerations” section for details.
Note 5.
Specification for packaged product only.
Note 6.
Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Note 7.
Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested for load regulation in the load
range from 100µA to 100mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
Note 8.
Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1V
differential.
Note 9.
Ground pin current is the regulator quiescent current plus pass transistor base current. The total current drawn from the supply is the sum of
the load current plus the ground pin current.
October 2003
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MIC5271
MIC5271
Micrel
Typical Characteristics
Dropout
Characteristics
-3.305
-1.5
-1
-100mA Load
-1
-2
-3
-4
SUPPLY VOLTAGE (V)
-3.275
-3.27
-3.265
-5
-3.26
0
-90
GROUND CURRENT (µA)
GROUND CURRENT (mA)
-3.28
Ground Current
vs. Output Current
-2.5
-2
-1.5
-1
-0.5
5VIN
0
0
-30
GROUND CURRENT (µA)
-3.29
-3.285
Ground Current
vs. Temperature
-1mA Load
0A Load
-15
-10
-5
Negative Enable Threshold
vs. Supply Voltage
DROPOUT VOLTAGE (mV)
ENABLE THRESHOLD (V)
-1.2
-1
Enable Off
-0.8
-0.6
-0.4
-0.2
0
-4
-7
-10
-13
SUPPLY VOLTAGE (V)
-30
-20
-16
0µA Load
-10
-1
-2
-3
-4
SUPPLY VOLTAGE (V)
-3.22
-3.2
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
-2.5
-100mA Load
-1.5
-1
-50A Load
-50mA Load
-1
-400
-300
-200
-100
-20
-40
-60
-80 -100
OUTPUT CURRENT (mA)
4
-10mA Load
-0.5
0
0
1.6
-1
-2
-3
-4
SUPPLY VOLTAGE (V)
-5
Positive Enable Threshold
vs. Supply Voltage
1.4
Enable On
1.2
1
Enable Off
0.8
0.6
0.4
0.2
0
-4
Dropout
vs. Output Current
-500
0
0
-1.5
Ground Current
vs. Temperature
-2
Ground Current
Characteristics
-2 -100mA Load
-5
-3
-600
-1.6
Enable On
-3.26
-3.24
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
-1.4
-1mA Load
-50 -100µA Load
-40
-0.5
-3.3
-3.28
-2.5
-60
-3.5
-3.34
-3.32
Ground Current
Characteristics
-70
0
0
-20
-40
-60
-80 -100
OUTPUT CURRENT (mA)
-25
-20
-80
-20
-40
-60
-80 -100
OUTPUT CURRENT (mA)
-3.38
-3.36
GROUND CURRENT (mA)
0
0
-3.295
-400
DROPOUT VOLTAGE (mV)
-0.5
OUTPUT VOLTAGE (V)
-2
Output Voltage
vs. Temperature
-3.4
ENABLE THRESHOLD (V)
OUTPUT VOLTAGE (V)
0 Load
-2.5
MIC5271
Output Voltage
vs. Output Current
-3.3
-3
GROUND CURRENT (µA)
OUTPUT VOLTAGE (V)
-3.5
-350
-7
-10
-13
SUPPLY VOLTAGE (V)
-16
Dropout
vs. Temperature
-10mA Load
-300
-250
-200
-150
0A Load
-100
-50
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
October 2003
MIC5271
Micrel
Typical Characteristics (continued)
DROPOUT VOLTAGE (mV)
-700
-600
Dropout
vs. Temperature
-100mA Load
-500
-400
-300
-50mA Load
-200
-100
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
October 2003
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MIC5271
MIC5271
Micrel
Functional Characteristics
Load Transient
VOUT
(10mV/div.)
-10mA
-100mA
COUT = 1µF Ceramic
VIN = 5V
VOUT = 3V
Output Current
(50mA/div.)
Output Current
(50mA/div.)
VOUT
(10mV/div.)
Load Transient
TIME (2ms/div.)
-10mA
-100mA
TIME (2ms/div.)
0V
VOUT
(1V/div.)
0V
Enable
(1V/div.)
Enable
(1V/div.)
VOUT
(1V/div.)
0V
TIME (20ms/div.)
MIC5271
COUT = 1µF Ceramic
VIN = 5V
VOUT = 3V
0V
TIME (20ms/div.)
6
October 2003
MIC5271
Micrel
Functional Diagram
GND
ADJ
VEN
VIN
VOUT
MIC5271-x.x
October 2003
7
MIC5271
MIC5271
Micrel
Applications Information
Thermal Considerations
The MIC5271 is a general-purpose negative regulator that
can be used in any system that requires a clean negative
voltage from a negative output. This includes post regulating
of DC-DC converters (transformer based or charge pump
based voltage converters). These negative voltages typically
require a negative low dropout voltage regulator to provide a
clean output from typically noisy lines.
Input Capacitor
A 1µF input capacitor should be placed from IN to GND if
there is more than 2 inches of wire or trace between the input
and the AC filter capacitor, or if a battery is used as the input.
Output Capacitor
The MIC5271 requires an output capacitor for stable operation. A minimum of 1µF of output capacitance is required. The
output capacitor can be increased without limitation to improve transient response. The output does not require ESR
to maintain stability, therefore a ceramic capacitor can be
used. High-ESR capacitors may cause instability. Capacitors
with an ESR of 3Ω or greater at 100kHz may cause a high
frequency oscillation.
Low-ESR tantalums are recommended due to the tight capacitance tolerance over temperature.
Ceramic chip capacitors have a much greater dependence
on temperature, depending upon the dielectric. The X7R is
recommended for ceramic capacitors because the dielectric
will change capacitance value by approximately 15% over
temperature. The Z5U dielectric can change capacitance
value by as much 50% over temperature, and the Y5V
dielectric can change capacitance value by as much as 60%
over temperature. To use a ceramic chip capacitor with the
Y5V dielectric, the value must be much higher than a tantalum to ensure the same minimum capacitor value over
temperature.
No-Load Stability
The MIC5271 does not require a load for stability.
Enable Input
The MIC5271 comes with an enable pin that allows the
regulator to be disabled. Forcing the enable pin higher than
the negative threshold and lower than the positive threshold
disables the regulator and sends it into a “zero” off-mode
current state. In this state, current consumed by the regulator
goes nearly to zero. The MIC5271 will be in the on mode when
the voltage applied to the enable pin is either greater than the
positive threshold or less than the negative threshold.
Absolute values will be used for thermal calculations to clarify
the meaning of power dissipation and voltage drops across
the part.
Proper thermal design for the MIC5271-5.0BM5 can be
accomplished with some basic design criteria and some
simple equations. The following information must be known
to implement your regulator design:
VIN = input voltage
VOUT = output voltage
IOUT = output current
TA = ambient operating temperature
IGND = ground current
Maximum power dissipation can be determined by knowing
the ambient temperature, TA, the maximum junction temperature, 125°C, and the thermal resistance, junction to
ambient. The thermal resistance for this part, assuming a
minimum footprint board layout, is 235°C/W. The maximum
power dissipation at an ambient temperature of 25°C can be
determined with the following equation:
PD(max) =
PD(max) =
PD = (VIN – VOUT)IOUT + VIN × IGND
Substituting PD(max), determined above, for PD and solving
for the operating conditions that are critical to the application
will give the maximum operating conditions for the regulator
circuit. The maximum power dissipation number cannot be
exceeded for proper operation of the device. The maximum
input voltage can be determined using the output voltage of
5.0V and an output current of 100mA. Ground current, of 1mA
for 100mA of output current, can be taken from the “Electrical
Characteristics ” section of the data sheet.
(
)
425mW = (100mA × VIN + 1mA × VIN ) − 500mW
425mW = VIN − 5.0V 100mA + VIN × 1mA
925mW = 101mA × VIN
ENABLE VOLTAGE (V)
-5
-3
MIC5271
VIN = 9.16Vmax
Therefore, a –5.0V application at 100mA of output current
can accept a maximum input voltage of –9.16V in a SOT-23-5
package. For a full discussion of heat sinking and thermal
effects on voltage regulators, refer to Regulator Thermals
section of Micrel’s “Designing with Low Dropout Voltage
Regulators” handbook.
Regulator On
Regulator Off
-1
-2
-3
-4
125°C − 25°C
235°C/W
The actual power dissipation of the regulator circuit can be
determined using one simple equation.
5
4
1
0
θ JA
PD(max) = 425mW
Enable Input
3
2
TJ(max) − TA
Regulator On
-5 -7 -9 -11 -13 -15
SUPPLY VOLTAGE (V)
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October 2003
MIC5271
Micrel
Adjustable Regulator Application
MIC5271BM5
–VIN
5
–IN
–OUT
4
R2
–VOUT
–EN
2
GND ADJ
3
R1
Figure 1. Adjustable Voltage Application
The MIC5271BM5 can be adjusted from 1.20V to 14V by
using two external resistors (Figure 1). The resistors set the
output voltage based on the following equation:
R2
)
R1
Where VREF = 1.20V
VOUT = VREF (1 +
October 2003
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MIC5271
MIC5271
Micrel
Package Information
1.90 (0.075) REF
0.95 (0.037) REF
1.75 (0.069)
1.50 (0.059)
3.00 (0.118)
2.60 (0.102)
DIMENSIONS:
MM (INCH)
1.30 (0.051)
0.90 (0.035)
3.02 (0.119)
2.80 (0.110)
0.20 (0.008)
0.09 (0.004)
10°
0°
0.15 (0.006)
0.00 (0.000)
0.50 (0.020)
0.35 (0.014)
0.60 (0.024)
0.10 (0.004)
SOT-23-5 (M5)
MICREL, INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131
TEL
+ 1 (408) 944-0800
FAX
+ 1 (408) 944-0970
WEB
USA
http://www.micrel.com
The information furnished by Micrel in this datasheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use.
Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can
reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into
the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s
use or sale of Micrel Products for use in life support appliances, devices or systems is at Purchaser’s own risk and Purchaser agrees to fully indemnify
Micrel for any damages resulting from such use or sale.
© 2003 Micrel, Incorporated.
MIC5271
10
October 2003