MIC5238-1.1BD5TR [MICROCHIP]
Fixed Positive LDO Regulator, 1.1V, 0.5V Dropout, BIPolar, PDSO5, MO-193, TSOT-23, 5 PIN;
| 型号： | MIC5238-1.1BD5TR |
| 厂家： | 
MICROCHIP |
| 描述： | Fixed Positive LDO Regulator, 1.1V, 0.5V Dropout, BIPolar, PDSO5, MO-193, TSOT-23, 5 PIN 光电二极管 输出元件 调节器 |
| 文件： | 总12页 (文件大小：1420K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC5238
Ultra-Low Quiescent Current, 150mA
µCap LDO Regulator
General Description
Features
The MIC5238 is an ultra-low voltage output, 150mA LDO
regulator. Designed to operate in a single supply or dual
supply mode, the MIC5238 consumes only 23µA of bias
current, improving efficiency. When operating in the dual
supply mode, the efficiency greatly improves as the higher
voltage supply is only required to supply the 23µA bias
current while the output and base drive comes off of the
much lower input supply voltage.
• Ultra-low input voltage range:1.5V to 6V
• Ultra-low output voltage:1.0V minimum output voltage
• Low dropout voltage: 310mV at 150mA
• High output accuracy: ±2.0% over temperature
• µCap: stable with ceramic or tantalum capacitors
• Excellent line and load regulation specifications
• Zero shutdown current
• Reverse leakage protection
• Thermal shutdown and current limit protection
• IttyBitty® SOT-23-5 package
As a µCap regulator, the MIC5238 operates with a 2.2µF
ceramic capacitor on the output, offering a smaller overall
solution. It also incorporates a logic-level enable pin that
allows the MIC5238 to be put into a zero off-current mode
when disabled.
The MIC5238 is fully protected with current limit and
thermal shutdown. It is offered in the IttyBitty® SOT-23-5
package with an operating junction temperature range of
–40°C to +125°C.
Applications
• PDAs and pocket PCs
• Cellular phones
• Battery powered systems
• Low power microprocessor power supplies
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
___________________________________________________________________________________________________________
Typical Application
Ultra-Low Voltage Application
IttyBitty is a registered trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
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Micrel, Inc.
MIC5238
Ordering Information
Part Number
Marking Code Pb-Free
Voltage**
Junction
Temp. Range
Package
Standard
Marking Code*
L410
MIC5238-1.0BM5
MIC5238-1.1BM5
MIC5238-1.3BM5
MIC5238-1.0BD5
MIC5238-1.1BD5
MIC5238-1.3BD5
Notes:
L410
L411
L413
N410
N411
N413
MIC5238-1.0YM5
MIC5238-1.1YM5
MIC5238-1.3YM5
MIC5238-1.0YD5
MIC5238-1.1YD5
MIC5238-1.3YD5
1.0V
1.1V
1.3V
1.0V
1.1V
1.3V
–40° to +125°C
–40° to +125°C
–40° to +125°C
–40° to +125°C
–40° to +125°C
–40° to +125°C
SOT-23-5
SOT-23-5
SOT-23-5
TSOT-23-5
TSOT-23-5
TSOT-23-5
L411
L413
N410
N411
N413
*
Under bar symbol ( _ ) may not be to scale.
** Other voltage options available. Contact Micrel Marketing for details.
Pin Configuration
5-Pin SOT-23 (M5)
5-Pin Thin SOT-23 (D5)
Pin Description
Pin Number
Pin Name
IN
Pin Function
Supply Input
Ground
1
2
3
GND
EN
Enable (Input): Logic Low = shutdown; Logic High = enable. Don not leave
open.
4
5
BIAS
OUT
Bias Supply Input
Regulator Output
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MIC5238
Absolute Maximum Ratings(1)
Operating Ratings(2)
Input Supply Voltage (VIN)................................. –0.3V to 7V
BIAS Supply Voltage (VBIAS).............................. –0.3V to 7V
Enable Supply Voltage (VEN)............................. –0.3V to 7V
Power Dissipation (PD)..............................Internally Limited
Junction Temperature (TJ) ........................–40°C to +125°C
Storage Temperature (TS).........................–65°C to +150°C
ESD Rating(3)......................................................1.5µA HBM
Supply Voltage (VIN)............................................ 1.5V to 6V
BIAS Supply Voltage (VBIAS)................................ 2.3V to 6V
Enable Supply Voltage (VEN).................................. 0V to 6V
Junction Temperature (TJ) ........................–40°C to +125°C
Package Thermal Resistance
SOT-23-5 (θJA).................................................235°C/W
Electrical Characteristics(4)
TA = 25°C with VIN = VOUT + 1V; VBIAS = 3.3V; IOUT = 100µA; VEN = 2V, bold values indicate –40°C < TJ < +125°C, unless
specified.
Parameter
Condition
Min
–1.5
–2
Typ
Max
+1.5
+2
Units
%
Output Voltage Accuracy
Variation from nominal VOUT
%
Line Regulation
V
BIAS = 2.3V to 6V, Note 5
0.25
0.04
0.7
0.5
4
%
Input Line Regulation
Load Regulation
Dropout Voltage
VIN = (VOUT 1V) to 6V
Load = 100µA to 150mA
IOUT = 100µA
%
1
%
50
mV
mV
mV
mV
mV
mV
µA
µA
mA
mA
mA
µA
µA
mA
µA
IOUT = 50mA
230
300
400
IOUT = 100mA
270
310
I
OUT = 150mA
450
500
BIAS Current, Note 6
Input Current, Pin 1
IOUT = 100µA
23
7
IOUT = 100µA
20
IOUT = 50mA, Note 7
IOUT = 100mA
0.35
1
I
OUT = 150mA
2
2.5
Ground Current in Shutdown
VEN ≤ 0.2V, VIN = 6V, VBIAS = 6V
VEN = 0V, VIN = 6V, VBIAS = 6V
VOUT = 0V
1.5
0.5
350
5
5
Short Circuit Current
Reverse Leakage
500
VIN = 0V, VEN = 0V, VOUT = nom VOUT
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MIC5238
Electrical Characteristics(4) cont.
TA = 25°C with VIN = VOUT + 1V; VBIAS = 3.3V; IOUT = 100µA; VEN = 2V, bold values indicate –40°C < TJ < +125°C, unless
specified.
Parameter
Condition
Min
Typ
Max
0.2
Units
Enable Input
Input Low Voltage
Input High Voltage
Enable Input Current
Regulator OFF
V
V
Regulator ON
2.0
VEN = 0.2V, Regulator OFF
VEN = 0.2V, Regulator ON
–1.0
0.01
0.1
1.0
1.0
µA
µA
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
4. Specification for packaged product only.
5. Line regulation measures a change in output voltage due to a change in the bias voltage.
6. Current measured from bias input to ground.
7. Current differential between output current and main input current at rated load current.
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MIC5238
Typical Characteristics
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MIC5238
Typical Characteristics cont.
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MIC5238
Functional Characteristics
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MIC5238
Functional Diagram
Block Diagram – Fixed Output Voltage
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MIC5238
TJ(MAX) is the maximum junction temperature of the die,
125°C, and TA is the ambient operating temperature. θJA is
layout dependent; Table 1 shows the junction-to-ambient
thermal resistance for the MIC5238.
Application Information
Enable/Shutdown
The MIC5238 comes with an active-high enable pin that
allows the regulator to be disabled. Forcing the enable pin
low 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. Forcing the enable pin high
enables the output voltage.
Package
θ
JA Recommended
Minimum Footprint
SOT-23-5
235°C/W
Table 1. SOT-23-5 Thermal Resistance
Input Bias Capacitor
The actual power dissipation of the regulator circuit can be
determined using the equation:
The input capacitor must be rated to sustain voltages that
may be used on the input. An input capacitor may be
required when the device is not near the source power
supply or when supplied by a battery. Small, surface
mount, ceramic capacitors can be used for bypassing.
Larger values may be required if the source supply has
high ripple.
PD = (VIN – VOUT) IOUT + VINIGND
Substituting PD(MAX) for PD and solving for the operating
conditions that are critical to the application will give the
maximum operating conditions for the regulator circuit. For
example, when operating the MIC5238-1.0BM5 at 50°C
with a minimum footprint layout, the maximum input voltage
for a set output current can be determined as follows.
Output Capacitor
The MIC5238 requires an output capacitor for stability. The
design requires 2.2µF or greater on the output to maintain
stability. The design is optimized for use with low-ESR
ceramic chip capacitors. High ESR capacitors may cause
high frequency oscillation. The maximum recommended
ESR is 3Ω. The output capacitor can be increased without
limit. Larger valued capacitors help to improve transient
response.
125°C - 50°C
235°C/W
D(MAX) = 319mW
PD(MAX)
=
P
The junction-to-ambient (θJA) thermal resistance for the
minimum footprint is 235°C/W, from Table 1. It is important
that the maximum power dissipation not be exceeded to
ensure proper operation. With very high input-to-output
voltage differentials, the output current is limited by the total
power dissipation. Total power dissipation is calculated
using the following equation:
X7R/X5R dielectric-type ceramic capacitors are recom-
mended because of their temperature performance. X7R-
type capacitors change capacitance by 15% over their
operating temperature range and are the most stable type
of ceramic capacitors. Z5U and Y5V dielectric capacitors
change value by as much as 50% and 60% respectively
over their operating temperature ranges. To use a ceramic
chip capacitor with Y5V dielectric, the value must be much
higher than a X7R ceramic capacitor to ensure the same
minimum capacitance over the equivalent operating
temperature range.
PD = (VIN – VOUT) IOUT + VIN x IGND + VBIAS x IBIAS
Since the bias supply draws only 18µA, that contribution
can be ignored for this calculation.
If we know the maximum load current, we can solve for the
maximum input voltage using the maximum power dissipa-
tion calculated for a 50°C ambient, 319mV.
PD(MAX) = (VIN – VOUT) IOUT + VIN x IGND
No-Load Stability
319mW = (VIN – 1V) 150mA + VIN x 2.8mA
The MIC5238 will remain stable and in regulation with no
load unlike many other voltage regulators. This is especially
important in CMOS RAM keep-alive applications.
Ground pin current is estimated using the typical
characteristics of the device.
469mW = VIN (152.8mA)
VIN = 3.07V
Thermal Considerations
The MIC5238 is designed to provide 150mA of continuous
current in a very small package. Maximum power
dissipation can be calculated based on the output current
and the voltage drop across the part. To determine the
maximum power dissipation of the package, use the
junction-to-ambient thermal resistance of the device and
the following basic equation:
For higher current outputs only a lower input voltage will
work for higher ambient temperatures.
Assuming a lower output current of 20mA, the maximum
input voltage can be recalculated:
319mW = (VIN – 1V) 20mA + VIN x 0.2mA
339mW = VIN x 20.2mA
VIN = 16.8V
TJ(max) - TA
PD(MAX)
=
Maximum input voltage for a 20mA load current at 50°C
ambient temperature is 16.8V. Since the device has a 6V
rating, it will operate over the whole input range.
θJA
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MIC5238
Dual Supply Mode Efficiency
Now, using a lower input supply of 1.5V, and powering the
bias voltage only from the 2.5V input, the efficiency is as
follows:
By utilizing a bias supply the conversion efficiency can be
greatly enhanced. This can be realized as the higher bias
supply will only consume a few µA’s while the input supply
will require a few mA’s. This equates to higher efficiency
saving valuable power in the system. As an example,
consider an output voltage of 1V with an input supply of
2.5V at a load current of 150mA. The input ground current
under these conditions is 2mA, while the bias current is
only 20µA. If we calculate the conversion efficiency using
the single supply approach, it is as follows:
Input power = VIN × output current + VIN × VIN ground
current + VBIAS x VBIAS ground current
Input power = 1.5 × 150mA + 1.5 × 0.002 + 2.5 × 0.0002 =
225mW
Output power = 1V × 150mA = 150mW
Efficiency = 150/225 × 100 = 66.6 %
Therefore, by using the dual supply MIC5238 LDO the
efficiency is nearly doubled over the single supply version.
Input power = VIN × output current + VIN × (VBIAS ground
current + VIN ground current)
This is a valuable asset in portable power management
applications equating to longer battery life and less heat
being generated in the application.
Input power = 2.5V × 150mA + 2.5 × (0.0002+0.002) =
380.5mW
This in turn will allow a smaller footprint design and an
extended operating life.
Output power = 1V × 0.15 = 150mW
Efficiency = 150/380.5 × 100 = 39.4%
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Micrel, Inc.
MIC5238
Package Information
5-Pin SOT-23 (M5)
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Micrel, Inc.
MIC5238
Package Information cont.
5-Pin Thin SOT-23 (D5)
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this data sheet 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 a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2003 Micrel, Incorporated.
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