MAX8505EEE ,3A, 1MHz, 1% Accurate, Internal Switch Step-Down Regulator with Power-OKfeatures 1% accurate output over load,line, and temperature variations. Adjustable soft-start is♦ F ..
MAX8505EEE+ ,3A, 1MHz, 1% Accurate, Internal Switch Step-Down Regulator with Power-OKfeatures current-limit, short-circuit, andthermal-overload protection and enables a ruggeddesign. O ..
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MB81C81A-35 ,CMOS 256K-BIT HIGH-SPEED SRAMMay 1990 00
Edition1.0 FUJITSU
M38 1 C8 1A-25/-35
CMOS 256K-BI T HIGH-SPEED SRAM
256K Words ..
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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MB81N643289-60FN ,8 x 256K x 32 bit double data rate FCRAMapplications where large memory density and high effective bandwidth arerequired and where a simple ..
MB8264A-10 , MOS 65536-BIT DYNAMIC RANDOM ACCESS MEMORY
MB8264A-10 , MOS 65536-BIT DYNAMIC RANDOM ACCESS MEMORY
MAX8505EEE-MAX8505EEE+-MAX8505EEE+T
3A, 1MHz, 1% Accurate, Internal Switch Step-Down Regulator with Power-OK
General DescriptionThe MAX8505 step-down regulator operates from a 2.6V
to 5.5V input and generates an adjustable output voltage
from 0.8V to 0.85 ✕VIN at up to 3A. With a 2.6V to 5.5V
bias supply, the input voltage can be as low as 2.25V.
The MAX8505 integrates power MOSFETs and
operates at 1MHz/500kHz switching frequency to
provide a compact design. Current-mode pulse-width-
modulated (PWM) control simplifies compensation with
ceramic or polymer output capacitors and provides
excellent transient response.
The MAX8505 features 1% accurate output over load,
line, and temperature variations. Adjustable soft-start is
achieved with an external capacitor. During the
soft-start period, the voltage-regulation loop is active.
This limits the voltage dip when the active devices,
such as microprocessors or ASICs connected to the
MAX8505’s output, apply a sudden load current step
upon passing their undervoltage thresholds.
The MAX8505 features current-limit, short-circuit, and
thermal-overload protection and enables a rugged
design. Open-drain power-OK (POK) monitors the
output voltage.
ApplicationsµP/ASIC/DSP/FPGA Core and I/O Supplies
Chipset Supplies
Server, RAID, and Storage Systems
Network and Telecom Equipment
FeaturesSaves Space—4.9mm x 6mm Footprint, 1µH
Inductor, 47µF Ceramic Output CapacitorInput Voltage Range
2.6V to 5.5V
Down to 2.25V with Bias Supply0.8V to 0.85 ✕VIN, 3A Output Ceramic or Polymer Capacitors±1% Output Accuracy Over Load, Line, and
TemperatureFast Transient ResponseAdjustable Soft-StartIn-Regulation Soft-Start Limits Output-Voltage
Dips at Power-OnPOK Monitors Output Voltage
MAX8505
3A, 1MHz, 1% Accurate, Internal Switch
Step-Down Regulator with Power-OK
Ordering Information19-2992; Rev 1; 9/10
PARTTEMP RANGEPIN-PACKAGEMAX8505EEE+-40°C to +85°C16 QSOPLX
PGND
PGND
GND
REF
COMP
TOP VIEW
MAX8505
QSOPVCC
BST
POK
CTL
Pin ConfigurationMAX8505
INPUT
2.6V TO 5.5V
ENABLE
POWER-OK
OUTPUT
0.8V TO
0.85 x VIN
BST
VCC
CTL
POKGND
REF
COMP
PGND
Typical Operating Circuit
Functional Diagram appears at end of data sheet.mx4.9m6-QSOP
EVALUATION KITAVAILABLE+Denotes a lead(Pb)-free/RoHS-compliant package.
MAX8505
3A, 1MHz, 1% Accurate, Internal Switch
Step-Down Regulator with Power-OK
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VIN= VCC= VCTL= +3.3V, VFB= 0.8V, VCOMP= 1.25V, CREF= 0.01µF, TA
= 0°C to +85°C, unless otherwise noted.)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.
CTL, FB, IN, VCCto GND.........................................-0.3V to +6V
COMP, REF, POK to GND..........................-0.3V to (VCC+ 0.3V)
BST to LX..................................................................-0.3V to +6V
PGND to GND.......................................................-0.3V to +0.3V
Continuous Power Dissipation (TA= +70°C)
16-Pin QSOP (derate 12.5mW/°C above +70°C).......1000mW
Operating Temperature Range
MAX8505EEE...................................................-40°C to +85°C
Storage Temperature Range.............................-65°C to +150°C
Junction Temperature......................................................+150°C
Lead Temperature (soldering, 10s).................................+300°C
Soldering Temperature (reflow).......................................+260°C
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
IN AND VCCIN Voltage RangeVIN2.25VCCV
VCC Voltage RangeVCC2.65.5V
VIN = 3.3V610IN Supply CurrentIINSwitching with no loadVIN = 5.5V10mA
VCC = 3.3V310
VCC Supply CurrentICCSwitching with no loadVCC = 5.5V6mA
Total Shutdown Current into IN
and VCCISHDNVIN = VCC = VBST - VLX = 5.5V, VCTL = 0V,
VLX = 0V2050µA
VCC rising2.402.55VCC Undervoltage Lockout
ThresholdUVLOthWhen LX starts/stops
switchingVCC falling2.22.35V
REFREF VoltageVREFIREF = 0µA, VIN = VCC = 2.6V to 5.5V0.7920.8000.808V
REF Shutdown ResistanceFrom REF to GND, VCTL = 0V13100Ω
REF Soft-Start CurrentVREF = 0.4V202530µA
Soft-Start Ramp TimeOutput from 0% to 100%, CREF = 0.01µF to
1µF32ms/µF
FB Regulation VoltageVIN = 2.6V to 5.5V0.7920.8000.808V
FB Input Bias CurrentVFB = 0.7V0.010.1µA
Maximum Output CurrentIOUT_MAXVIN = VCC = 3.3V, VOUT = 1.2V,
L = 1µH/5.9mΩ (Note 1)3A
FB high10.51213.5FB Threshold for POK TransitionFB rising or fallingFB low-13.5-12-10.5%
FB to POK DelayFB rising or falling50µs
COMPCOMP TransconductanceFrom FB to COMP60100160µS
Gain from FB to COMPVCOMP = 1.25V to 1.75V80dB
MAX8505
3A, 1MHz, 1% Accurate, Internal Switch
Step-Down Regulator with Power-OK
ELECTRICAL CHARACTERISTICS (continued)(VIN= VCC= VCTL= +3.3V, VFB= 0.8V, VCOMP= 1.25V, CREF= 0.01µF, TA
= 0°C to +85°C, unless otherwise noted.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSCOMP Clamp Voltage, LowVIN = VCC = 2.6V, 3.3V, 5.5V, VFB = 0.9V0.450.751.00V
COMP Clamp Voltage, HighVIN = VCC = 2.6V, 3.3V, 5.5V, VFB = 0.7V1.71.92.1V
COMP Shutdown ResistanceFrom COMP to GND, VCTL = 0V13100Ω
LX (All LX Outputs Connected Together)VIN = VBST - VLX = 3.3V3874LX On-Resistance, HighVIN = VBST - VLX = 2.6V42mΩ
VIN = VBST - VLX = 3.3V3874LX On-Resistance, LowVIN = VBST - VLX = 2.6V42mΩ
LX C ur r ent- S ense Tr ansr esi stanceRTFrom LX to COMP0.0680.0860.104Ω
Sourcing, Typical Application Circuit4.65.66.6LX Current-Limit ThresholdSinking, VIN = VCC = 2.6V to 5.5V-4.3-2.6-1.0A
VLX = 5.5V100LX Leakage CurrentVIN = VCC = 5.5V,
VCTL = 0VVLX = 0V-100µA
VCTL = VCC0.8511.15LX Switching FrequencyVIN = VCC = 2.6V, 3.3V,
5.5VVCTL = 2/3VCC0.440.50.56MHz
LX Minimum Off-TimeVIN = VCC = 2.6V, 3.3V, 5.5V95110135ns
500kHz9094LX Maximum Duty CycleVIN = VCC = 2.6V, 3.3V,
5.5V1MHz8489%
500kHz58LX Minimum Duty CycleVIN = VCC = 2.6V, 3.3V,
5.5V1MHz1015%
SLOPE COMPENSATIONSlope CompensationExtrapolated to 100% duty cycle245300400mV
BSTVLX = 5.5V10
VLX = 0V10BST Shutdown Supply Current(VBST - VLX) = VIN =
VCC = 5.5V, VCTL = 0V
LX open10
CTLFor 1MHz80
For 500kHz5570CTL Input ThresholdVIN = VCC = 2.6V,
3.3V, 5.5VFor shutdown45
% of
VCC
CTL Input CurrentVCTL = 0V or 5.5V, VIN = VCC = 5.5V-1+1µA
POK (Power-OK)POK Output Voltage, LowVFB = 0.6V or 1.0V, IPOK = 2mA25100mV
POK Leakage CurrentVPOK = 5.5V0.0011µA
POK Fault Delay TimeFrom FB to POK, any threshold2550100µs
THERMAL SHUTDOWNThermal-Shutdown ThresholdWhen LX stops switchingTJ rising+170°C
Thermal-Shutdown Hysteresis20°C
MAX8505
3A, 1MHz, 1% Accurate, Internal Switch
Step-Down Regulator with Power-OK
ELECTRICAL CHARACTERISTICS(VIN= VCC= VCTL= +3.3V, VFB= 0.8V, VCOMP= 1.25V, CREF= 0.01µF, TA
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
IN AND VCCIN Voltage RangeVIN2.25VCCV
VCC Voltage Range2.65.5V
IN Supply CurrentIINSwitching with no loadVIN = 3.3V10mA
VCC Supply CurrentICCSwitching with no loadVCC = 3.3V10mA
Total Shutdown Current into IN
and VCCISHDNVIN = VCC = VBST - VLX = 5.5V, VCTL = 0V,
VLX = 0V50µA
VCC rising2.55VCC Undervoltage Lockout
ThresholdUVLOthWhen LX starts/stops
switchingVCC falling2.2V
REFREF VoltageVREFIREF = 0µA, VIN = VCC = 2.6V to 5.5V0.7910.808V
REF Shutdown ResistanceFrom REF to GND, VCTL = 0V100Ω
REF Soft-Start CurrentVREF = 0.4V2030µA
FB Regulation VoltageVFBVIN = 2.6V to 5.5V0.7910.808V
FB Input Bias CurrentVFB = 0.7V0.1µA
Maximum Output CurrentIOUT_MAXVIN = VCC = 3.3V, VOUT = 1.2V,
L = 1µH/5.9mΩ (Note 1)3A
FB high10.513.5FB Threshold for POK TransitionFB rising or fallingFB low-13.5-10.5%
COMPCOMP TransconductanceFrom FB to COMP60160µS
COMP Clamp Voltage, LowVIN = VCC = 2.6V, 3.3V, 5.5V, VFB = 0.9V0.451.00V
COMP Clamp Voltage, HighVIN = VCC = 2.6V, 3.3V, 5.5V, VFB = 0.7V1.72.1V
COMP Shutdown ResistanceFrom COMP to GND, VCTL = 0V100Ω
LX (All LX Outputs Connected Together)LX On-Resistance, HighVIN = VBST - VLX = 3.3V74mΩ
LX On-Resistance, LowVIN = VBST - VLX = 3.3V74mΩ
LX C ur r ent- S ense Tr ansr esi stanceRTFrom LX to COMP0.0680.104Ω
Sourcing, Typical Application Circuit4.6 5.6LX Current-Limit ThresholdSinking, VIN = VCC = 2.6V to 5.5V-4.3 -1.0A
VLX = 5.5V 100LX Leakage CurrentVIN = VCC = 5.5V,
VCTL = 0VVLX = 0V-100µA
VCTL = VCC0.851.15LX Switching FrequencyVIN = VCC = 2.6V,
3.3V, 5.5VV C TL = 2/3 ✕ V C C 0.440.56MHz
LX Minimum Off-TimeVIN = VCC = 2.6V, 3.3V, 5.5V95 135ns
MAX8505
3A, 1MHz, 1% Accurate, Internal Switch
Step-Down Regulator with Power-OK
Note 1:Under normal operating conditions, COMP moves between 1.25V and 2.15V as the duty cycle changes from 10% to 90%
and peak inductor current changes from 0 to 3A. Maximum output current is related to peak inductor current, inductor value
input voltage, and output voltage by the following equations:
where VOUT= output voltage; ILIM= current limit of high-side switch; tS= switching period; RL= ESR of inductor; RNLS=
on-resistance of low-side switch; L = inductor. Equations for ILIMand D are shown as follows:
where ILIM_DC100= current limit at D = 100%; RT= transresistance from LX to COMP; VSW= slope compensation (310mV
±20%); D = duty cycle:
where VOUT= output voltage; VIN= input voltage; IO= output current; RL= ESR of inductor; RNHS= on-resistance of high-
side switch; RNLS= on-resistance of low-side switch. See the Typical Application Circuitfor external components.
Note 2:Specifications to -40°C are guaranteed by design and not production tested.
Note 3:LX has internal clamp diodes to PGND and IN pins 2 and 4. Applications that forward bias these diodes should take care
not to exceed the IC’s package power dissipation limits.
Note 4:When connected together, the LX output is designed to provide 3.5ARMScurrent.VIRRRR
OUTONLSLONLSNHS=++−VDLIMLIMDCSW=+−1001IDtVLRRLOUTMAXLIMSOUTNLSL_/()/=−−××−××+2
ELECTRICAL CHARACTERISTICS (continued)(VIN= VCC= VCTL= +3.3V, VFB= 0.8V, VCOMP= 1.25V, CREF= 0.01µF, TA
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS500kHz90LX Maximum Duty CycleVIN = VCC = 2.6V, 3.3V,
5.5V1MHz84%
500kHz8LX Minimum Duty CycleVIN = VCC = 2.6V, 3.3V,
5.5V1MHz15%
SLOPE COMPENSATIONSlope CompensationExtrapolated to 100% duty cycle245406mV
BSTVLX = 5.5V10
VLX = 0V10BST Shutdown Supply Current(VBST - VLX) = VIN =
VCC = 5.5V, VCTL = 0V
LX open10
CTLFor 1MHz80
For 500kHz5570CTL Input ThresholdVIN = VCC = 2.6V,
3.3V, 5.5V
For shutdown45
% of
VCC
CTL Input CurrentVCTL = 0V or 5.5V, VIN = VCC = 5.5V-1+1µA
POK (Power-OK)POK Output Voltage, LowVFB = 0.6V or 1.0V, IPOK = 2mA100mV
POK Leakage CurrentVPOK = 5.5V1µA
POK Fault Delay TimeFrom FB to POK, any threshold25100µs
MAX8505
3A, 1MHz, 1% Accurate, Internal Switch
Step-Down Regulator with Power-OK
Typical Operating Characteristics(Typical values are at VIN= VCC= VCTL= 5V, VOUT= 1.2V, IOUT= 3A, and TA= +25°C, unless otherwise noted.)
EFFICIENCY vs. OUTPUT CURRENT
(VIN = VCC = 5V, fSW = 1MHz)MAX8505 toc01
OUTPUT CURRENT (A)
EFFICIENCY (%)21
A: VOUT = 3.3V
B: VOUT = 2.5V
C: VOUT = 1.2V
D: VOUT = 0.8V
EFFICIENCY vs. OUTPUT CURRENT
(VIN = VCC = 3.3V, fSW = 500kHz)MAX8505 toc02
OUTPUT CURRENT (A)
EFFICIENCY (%)21
A: VOUT = 2.5V
B: VOUT = 1.8V
C: VOUT = 1.2V
D: VOUT = 0.8VD
EFFICIENCY vs. OUTPUT CURRENT
(VIN = VCC = 3.3V, fSW = 1MHz)MAX8505 toc03
OUTPUT CURRENT (A)
EFFICIENCY (%)21
A: VOUT = 2.5V
B: VOUT = 1.8V
C: VOUT = 1.2V
D: VOUT = 0.8V
EFFICIENCY vs. OUTPUT CURRENT
(VIN = 2.5V, VCC = 5V, fSW = 1MHz)MAX8505 toc04
OUTPUT CURRENT (A)
EFFICIENCY (%)21
A: VOUT = 1.8V
B: VOUT = 1.2V
C: VOUT = 0.8V
FREQUENCY vs. INPUT VOLTAGE AND
TEMPERATUREMAX8505 toc05
INPUT VOLTAGE (V)
FREQUENCY (MHz)
+85°C
+25°C
-40°C
FREQUENCY vs. INPUT VOLTAGE AND
TEMPERATUREMAX8505 toc06
FREQUENCY (kHz)
+85°C
+25°C
-40°C
OUTPUT LOAD REGULATIONMAX8505 toc07
OUT
(mV)21
A: VOUT = 0.8V
B: VOUT = 1.2V
C: VOUT = 1.8V
D: VOUT = 2.5VD
VIN = VCC = 3.3V
MAX8505
3A, 1MHz, 1% Accurate, Internal Switch
Step-Down Regulator with Power-OK
SHUTDOWN SUPPLY CURRENT
vs. INPUT VOLTAGEMAX8505 toc08
INPUT VOLTAGE (V)
SHUTDOWN SUPPLY CURRENT (mA)
fSW = 1MHz
CURRENT LIMIT vs. OUTPUT VOLTAGEMAX8505 toc09
OUTPUT VOLTAGE (V)
CURRENT LIMIT (A)
fSW = 1MHz
OUTPUT SHORT-CIRCUIT CURRENT
vs. INPUT VOLTAGEMAX8505 toc10
INPUT VOLTAGE (V)
OUTPUT SHORT-CIRCUIT CURRENT (A)
fSW = 1MHz
GND-MEASURED TEMPERATURE
vs. OUTPUT CURRENTMAX8505 toc11
OUTPUT CURRENT (A)
GND-MEASURED TEMPERATURE (
°C)
TA = +85°C
TA = +25°C
TA = -40°C
VIN = 5V,
VOUT = 1.5V
REFERENCE VOLTAGE
vs. TEMPERATUREMAX8505 toc12
TEMPERATURE (°C)
REFERENCE VOLTAGE (V)603510-15
fSW = 1MHz
TRANSIENT RESPONSE
(VIN = 5V, VOUT = 1.2V)MAX8505 toc13
40μs/div
OUTPUT VOLTAGE
AC-COUPLED
100mV/div
2.25A
0.75A
OUTPUT
CURRENT
1A/div
Typical Operating Characteristics (continued)(Typical values are at VIN= VCC= VCTL= 5V, VOUT= 1.2V, IOUT= 3A, and TA= +25°C, unless otherwise noted.)
MAX8505
3A, 1MHz, 1% Accurate, Internal Switch
Step-Down Regulator with Power-OK
TRANSIENT RESPONSE
(VIN = 3.3V, VOUT = 1.2V)MAX8505 toc14
40μs/div
OUTPUT VOLTAGE
AC-COUPLED
100mV/div
2.25A
0.75A
OUTPUT
CURRENT
1A/div
SWITCHING WAVEFORM
(VIN = 5V, VOUT = 1.2V, IOUT = 2.5A)MAX8505 toc15
200ns/div
INDUCTOR CURRENT
AC-COUPLED
2A/div
VOUT
AC-COUPLED
20mV/div
VLX
2V/div
SOFT-START/SHUTDOWN WAVEFORM
(VIN = 3.3V, VOUT = 1.2V, IOUT = 3A, CREF = 0.068μF)MAX8505 toc16
400μs/div
VOUT
500mV/div
VCTRL
5V/div
VPOK
5V/div
INPUT CURRENT
1A/div
TRANSIENT RESPONSE DURING SOFT-STARTMAX8505 toc17
100μs/div
VOUT
100mV/div
IOUT
2A/div
Typical Operating Characteristics (continued)(Typical values are at VIN= VCC= VCTL= 5V, VOUT= 1.2V, IOUT= 3A, and TA= +25°C, unless otherwise noted.)
