MAX8515EXK-T ,Wide-Input 0.6V Shunt Regulators for Isolated DC-to-DC ConvertersApplicationsIsolated DC-to-DC Converters Network, Telecom, and Cellular Base StationPower SuppliesT ..
MAX8516EUB ,1.425V to 3.6V Input, 1A, 0.2V Dropout LDO Regulatorsfeatures a 150ms power-on reset output.Typical Operating Circuit®The parts are packaged in a 10-pin ..
MAX8516EUB+ ,1.425V to 3.6V Input, 1A, 0.2V Dropout LDO RegulatorsFeaturesThe MAX8516/MAX8517/MAX8518 low-dropout linear ● 1.425V to 3.6V Input Voltage Rangeregulato ..
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MAX8516EUB+ ,1.425V to 3.6V Input, 1A, 0.2V Dropout LDO RegulatorsApplicationsMAX8516MAX8517● Servers ● Post RegulatorsMAX8518● Storage ● NotebooksPOWER-ON RESET4.7µ ..
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MB81C81A-35 ,CMOS 256K-BIT HIGH-SPEED SRAMMay 1990 00
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MB81F643242C-10FN ,4 x 512K x 32 bit synchronous dynamic RAMFUJITSU SEMICONDUCTORADVANCED INFO. AE0.1EDATA SHEETMEMORYCMOS4 · 512 K · 32 BITSYNCHRONOUS DYNAMIC ..
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MAX8515EXK-T
Wide-Input 0.6V Shunt Regulators for Isolated DC-to-DC Converters
General DescriptionThe MAX8515A/MAX8515 shunt regulators simplify the
design of voltage regulation and overvoltage protection
(OVP) functions in high-accuracy isolated DC-to-DC con-
verters with output voltages as low as 0.6V. The devices
have supply voltage and feedback inputs separated from
the output shunt stage, and can operate directly from the
DC-to-DC converter output stage when the output voltage
is 1.8V to 18V. Alternately, the MAX8515A/MAX8515 input
stage can be biased from an unregulated 1.7V to 28V
supply, independent of DC-to-DC converter output volt-
age. The MAX8515A/MAX8515 shunts 20mA when the
output voltage is as low as 0.2V.
The MAX8515A features an initial output accuracy of
0.5% at +25°C and 1% from -40°C to +85°C and provides
the output voltage regulation function for isolated DC-to-
DC converters. The MAX8515 features initial output
accuracy of 1% at +25°C and 1.8% from -40°C to +85°C
and can provide an output OVP function for isolated DC-
to-DC converters. High open-loop bandwidth allows
design of high-bandwidth DC-to-DC converters.
Low-cost, low-dropout linear regulators can be designed
with the MAX8515A/MAX8515 and an external NPN tran-
sistor for cost-conscious applications that do not require
overcurrent, short-circuit, or overtemperature protection.
The MAX8515/MAX8515A are available in space-saving
5-pin SC70 and SOT23 packages and are specified over
the -40°C to +85°C extended temperature range. An eval-
uation kit is available to speed designs.
ApplicationsIsolated DC-to-DC Converters
Network, Telecom, and Cellular Base Station
Power Supplies
Low-Dropout Linear Regulators
Shunt Regulator
Adjustable Voltage Reference
FeaturesMAX8515A
0.6V ±0.5% Initial Accuracy at +25°C
0.6V ±1% Accuracy from -40°C to +85°CMAX8515
0.6V ±1% Initial Accuracy at +25°C
0.6V ±1.8% Accuracy from -40°C to +85°CSinks 20mA at 0.2V to 18VInput Voltage Range from 1.7V to 28VDirectly Drives Optocouplers0.2ΩDynamic Output ImpedanceSpace-Saving 5-Pin SC70 or SOT23 Packages
MAX8515A/MAX8515
Isolated DC-to-DC Converters
Ordering Information
Pin Configurationypical Operating Circuit
Functional Diagram appears at end of data sheet.
Selector Guide appears at end of data sheet.
MAX8515A/MAX8515
Wide-Input 0.6V Shunt Regulators for
Isolated DC-to-DC Converters
ABSOLUTE MAXIMUM RATINGSStresses 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.
IN to GND...............................................................-0.3V to +30V
OUT to GND...........................................................-0.3V to +20V
FB to GND.................-0.3V to the lower of 5.5V and (VIN+0.3V)
PGND to GND.......................................................-0.3V to +0.3V
Continuous Power Dissipation (TA =+70°C)
5-Pin SC70 (derate 3.1mW/°C above +70°C)...........246.9mW
5-Pin Thin SOT23 (derate 9.1mW/°C above +70°C)....727mW
Operating Temperature Range...........................-40°C to +85°C
Junction Temperature Range............................-40°C to +150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
ELECTRICAL CHARACTERISTICS(VIN = 3.3V, OUT = FB, IOUT = 5mA, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
Note 1:Devices are production tested at TA = +25°C, limits over temperature are guaranteed by design.
MAX8515A/MAX8515
Wide-Input 0.6V Shunt Regulators for
Isolated DC-to-DC ConvertersFB BIAS CURRENT (nA)
FB BIAS CURRENT
vs. TEMPERATURE
MAX8515 toc01
TEMPERATURE (°C)35-1510-4085
OUT-LEAKAGE CURRENT (nA)
OUT-LEAKAGE CURRENT
vs. TEMPERATUREMAX8515 toc02
TEMPERATURE (°C)35-1510-408570
GAIN AND PHASE vs. FREQUENCY
VOUT = 0.6V
MAX8515 toc03
FREQUENCY (kHz)
GAIN (dB)
PHASE (DEGREES)10
GAIN AND PHASE vs. FREQUENCY
VOUT = 6V
MAX8515 toc04
FREQUENCY (kHz)
GAIN (dB)
PHASE (DEGREES)
OUTPUT VOLTAGE SLEW RATEMAX8515 toc05
2µs/div
0.55V
0.66V
VOUT: 2V/div
VFB: 200mV/div
SUPPLY CURRENT vs. LOAD CURRENTMAX8515 toc07
LOAD CURRENT (mA)
SUPPLY CURRENT (mA)105
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX8515 toc06
FREQUENCY (Hz)
PSRR (dB)100101
0.110k
Typical Operating Characteristics(VIN= 3.3V, IOUT = 5mA, FB = OUT, circuit in Figure 1, C1 = 0.1µF, C2 = 1µF, TA = +25°C, unless otherwise specified.)
MAX8515A/MAX8515
Detailed DescriptionThe MAX8515A/MAX8515 adjustable shunt regulators
feature isolated supply inputs and outputs, ideal for isolat-
ed power-supply applications using an optocoupler in the
feedback path. The MAX8515A/MAX8515 sink 20mA with
VOUTat 0.2V. The wide input supply range allows the
device to operate from 1.7V to 28V. The MAX8515A/
MAX8515 compare the FB input to a precision 600mV
reference. If the FB input is low, OUT sinks no current. If
FB rises above 600mV, OUT sinks up to 20mA.
Applications Information
Shunt Regulator/Adjustable
Voltage ReferenceFigure 1 shows the MAX8515A/MAX8515 configured as a
shunt regulator. Connect FB to OUT for an output voltage
of 0.6V. Connect a 1.0µF capacitor from OUT to GND
when the output voltage is 0.6V. A resistor-divider con-
nected from OUT to GND produces higher output volt-
ages and allows for a smaller output capacitor. The
value of the output capacitor is inversely proportional to
the output voltage:
Set the current limit with a resistor connected from IN to
OUT. This type of shunt regulator is limited to low-current
applications. The MAX8515A/MAX8515 can typically sink
up to 20mA in this application.
Figure 2 shows the test circuits for gain and phase plots.
Wide-Input 0.6V Shunt Regulators for
Isolated DC-to-DC Converters
Typical Operating Characteristics (continued)(VIN= 3.3V, IOUT= 5mA, FB = OUT, circuit in Figure 1, C1 = 0.1µF, C2 = 1µF, TA = +25°C, unless otherwise specified.)
Optical Feedback
Setting VOUTFigure 3 displays an application circuit using the
MAX8515A/MAX8515 in an opto-isolated feedback cir-
cuit. The maximum bias current for the photodiode is
set with R1. The isolated DC-to-DC converter compen-
sation circuit is formed with R2, C3, and C4. Resistors
R3 and R4 set the isolated DC-to-DC converter output
voltage. C1 decouples the input supply and C2 is
needed to stabilize the MAX8515A/MAX8515. Calculate
VREG with the following equation:
Set R4 to 10kΩand calculate R3 by:
For example, given a regulator output voltage of 1.8V
and R4 = 10kΩ, R3 is found to be 20kΩ.
Compensation CircuitA typical compensation scheme is depicted in Figure 3.
C3 provides an integrator function that minimizes out-
put regulation error.
R2 provides additional phase compensation at the zero
frequency fz:
The midband gain is given by:
Add C4 for high-frequency noise rejection. Determine
R2 based on the midband gain required by the isolated
power supply. Choose fzbased on the power supply
small-signal transfer function. Calculate C3 once fz
is known.
MAX8515A/MAX8515
Wide-Input 0.6V Shunt Regulators for
Isolated DC-to-DC Converters
MAX8515A/MAX8515
Overvoltage ProtectionFigure 4 shows an isolated OVP circuit. R1 limits the
current supplied to the photodiode. R2 limits the
MAX8515A/MAX8515 input current. R3 and R4 set the
trip threshold for the OVP. C1 is the input supply
decoupling capacitor.
Values for R3 and R4 are chosen based on the needed
OVP threshold. For example, a trip threshold of 25%
above the rated output voltage is needed for an OVP
circuit. The values of R3 can be determined from the
following equation once R4 is chosen; 10kΩis recom-
mended for R4. Then, R3 = 6.2kΩ.
where VOVP= 0.8V x 1.25 for the given example.
Linear RegulatorUse an external pass transistor in conjunction with the
MAX8515A/MAX8515 to create a linear regulator as
shown in Figure 5. Determine the output voltage of the
regulator by:
Choose R1 to maintain load regulation up to a 2A load.
Use the following equation:
where IO_MAXis the rated maximum output current,
which is 2A in this application circuit. VREGis the output
voltage of the linear regulator. VBEis the base-to-emitter
forward voltage of Q1, and βis the minimum current gain
of Q1 at rated load current. VINis the minimum input volt-
age at IN. For the typical application circuit, VIN_MIN=
2.375V, VREG= 1.0V, VBE= 0.65V, and β= 180. Choose
R1 = 15Ωfor fast transient response. C1 is the input
decoupling capacitor and C2 is the compensation
capacitor. Use a 1µF, 6.3V capacitor for this application.
Figure 6 shows a typical load-regulation curve for the cir-
cuit in Figure 5. This circuit does not provide short-circuit,
overcurrent, or overtemperature protection.
Wide-Input 0.6V Shunt Regulators for
Isolated DC-to-DC Converters
