MAX1973EUB+ ,Smallest 1A, 1.4MHz Step-Down RegulatorsApplications that forward bias these diodes should take care not to exceedthe IC package power diss ..
MAX1974EUB ,Smallest 1A, 1.4MHz Step-Down RegulatorsELECTRICAL CHARACTERISTICS(V = V = 3.3V, FB = OUT, T = 0°C to +85°C, unless otherwise noted. Typica ..
MAX1974EUB+ ,Smallest 1A, 1.4MHz Step-Down RegulatorsApplicationsOrdering InformationNetwork EquipmentPART TEMP RANGE PIN-PACKAGECellular Base StationsM ..
MAX1974EUB+ ,Smallest 1A, 1.4MHz Step-Down Regulatorsapplications. Forced PWM operationensures a constant switching frequency over all load♦ Fixed-Frequ ..
MAX1974EUB+T ,Smallest 1A, 1.4MHz Step-Down RegulatorsFeaturesThe MAX1973/MAX1974 are constant-frequency 2♦ Tiny Circuit Footprint of 0.19in1.4MHz pulse- ..
MAX1976AETA130+T ,Low-Input-Voltage, 300mA LDO Regulators with RESET in SOT and TDFNMAX1963A/MAX1976A19-3684; Rev 1; 5/12Low-Input-Voltage, 300mA LDO Regulators with RESET in SOT and ..
MAX4951AECTP+ ,SATA I/II Bidirectional Redriver with High ESD and Cable DetectApplications TOP VIEWLaptop Computers15 14 13 12 11Docking StationsDesktop ComputersV 10 VCC 16 CCS ..
MAX4951BECTP+ ,SATA I/II/III Bidirectional Redriver with Input Equalization and Preemphasisfeatures channel-independent digital preemphasis controls to drive SATA outputs over longer S Inlin ..
MAX4951BECTP+ ,SATA I/II/III Bidirectional Redriver with Input Equalization and Preemphasisfeatures high electrostatic discharge (ESD) Q8kV Human S Drive DetectionBody Model (HBM) protection ..
MAX4951BECTP+T ,SATA I/II/III Bidirectional Redriver with Input Equalization and PreemphasisApplicationsLaptop ComputersServersDesktop ComputersDocking StationsData Storage/Workstations ___ M ..
MAX4951BECTP+TGH7 ,SATA I/II/III Bidirectional Redriver with Input Equalization and PreemphasisELECTRICAL CHARACTERISTICS(V = +3.0V to +3.6V, C = 12nF, R = 50I, T = 0NC to +70NC, unless otherwis ..
MAX4951CCTP+ ,6Gbps SATA Bidirectional Redriver with Input Equalization, Preemphasis, and Advanced Power ManagementELECTRICAL CHARACTERISTICS(V = +3.0V to +3.6V, C = 10nF coupling capacitor on each output, R = 50I, ..
MAX1973EUB+-MAX1974EUB+-MAX1974EUB+T
Smallest 1A, 1.4MHz Step-Down Regulators
General DescriptionThe MAX1973/MAX1974 are constant-frequency
1.4MHz pulse-width-modulated (PWM) current-mode
step-down regulators. The output voltage can be set as
low as 0.75V using an external voltage-divider, or it can
be set to preset outputs of 1V, 1.5V (MAX1974), 1.8V,
or 2.5V (MAX1973) without requiring external resistors.
The MAX1973 also includes a voltage-margining fea-
ture that offsets the output voltage up or down 4% to
facilitate board-level production testing.
A fixed 1.4MHz operating frequency ensures operation
outside the DSL frequency band, provides fast transient
response, and allows the use of small external compo-
nents. Only 4.7µF input and output ceramic capacitors
are needed for 1A applications. Forced PWM operation
ensures a constant switching frequency over all load
conditions.
Output voltage accuracy is ±1% over load, line, and
temperature operating ranges. The MAX1973 features
voltage margining; the MAX1974 provides a POK out-
put to indicate when the output has reached 90% of its
nominal regulation voltage. Both devices are available
in small 10-pin µMAX packages.
ApplicationsNetwork Equipment
Cellular Base Stations
DSL and Wireless Modems/Routers
Optical Modules
Central-Office DSL and Telecom
DSP/ASIC Core and IO supplies
FeaturesTiny Circuit Footprint of 0.19in2Ultra-Low Circuit Height of 1.8mm4.7µF Ceramic Input and Output Capacitors2.6V to 5.5V Input Voltage1A Output Current1% AccurateBuilt-In ±4% Logic-Controlled Voltage Margining
(MAX1973)Preset 1V, 1.5V, 1.8V, 2.5V, or 0.75V to VIN
Adjustable OutputFixed-Frequency PWM Current-Mode Operation1.4MHz Switching Frequency, Operate Outside
DSL Band100% Duty-Cycle Dropout CapabilitySmall External Components
MAX1973/MAX1974
Smallest 1A, 1.4MHz Step-Down RegulatorsCTL1
PGNDSS
COMP
FBSEL
MAX1973
μMAX
TOP VIEW
CTL2GND
PGNDSS
COMP
FBSEL
MAX1974
μMAX
POKGND
Pin Configurations
Ordering InformationMAX1973
COMP
FBSEL
GND
CTL1
CTL2
PGND
INPUT
2.6V TO 5.5V
MAX1974 OUTPUT DOWN TO 0.75V
VOLTAGE
MARGINING
ON/OFF
OUTPUT
1.25V TO VIN
Typical Operating Circuit19-2547; Rev 0; 7/02
PARTTEMP RANGEPIN-PACKAGE
MAX1973EUB-40°C to +85°C10 µMAX
MAX1974EUB-40°C to +85°C10 µMAX
Selector Guide appears at end of data sheet.
MAX1973/MAX1974
Smallest 1A, 1.4MHz Step-Down Regulators
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, POK, CTL1, CTL2, FBSEL, ON to GND..............-0.3V to +6V
COMP, FB, SS to GND................................-0.3V to (VIN+ 0.3V)
PGND to GND.......................................................-0.3V to +0.3V
LX Current (Note 1)...............................................-2.4A to +2.4A
Continuous Power Dissipation (TA= +70°C)
10-Pin µMAX (derate 5.6mW/°C above +70°C)..........444mW
Operating Temperature Range...........................-40°C to +85°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
ELECTRICAL CHARACTERISTICS(VIN= VCTL_= 3.3V, FB = OUT, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETERCONDITIONSMINTYPMAXUNITSIN Voltage Range2.65.5V
IN Undervoltage Lockout
ThresholdRising and falling, hysteresis is 25mV (typ)2.22.352.5V
Supply CurrentSwitching with no load4.07.5mA
Supply Current in DropoutVOUT set for 3.6V35mA
Shutdown Supply CurrentVIN = 5.5V0.110µA
MAX19731.25VINOutput Voltage RangeMAX19740.75VINV
FBSEL not connected1.23751.251.2625
FBSEL = GND1.78201.81.8180MAX1973
FBSEL = IN2.47502.52.5250
FBSEL not connected0.74250.750.7575
FBSEL = GND0.991.001.01
FB Regulation Voltage
MAX1974
FBSEL = IN1.4851.5001.515
FB Regulation Voltage
Positive Voltage MarginingMAX1973, CTL1 = GND, CTL2 = IN+3+4+5%
FB Regulation Voltage
Negative Voltage MarginingMAX1973, CTL1 = IN, CTL2 = GND-3-4-5%
FB Input Resistance to GND in
Preset Output Modes103070kΩ
FB Input Bias CurrentFBSEL not connected-0.10.01+0.1µA
SS (REFERENCE OUTPUT)MAX19740.75SS VoltageMAX19731.25V
Note 1:LX has internal clamp diodes to IN and PGND. Applications that forward bias these diodes should take care not to exceed
the IC package power dissipation limit.
MAX1973/MAX1974
Smallest 1A, 1.4MHz Step-Down Regulators
ELECTRICAL CHARACTERISTICS (continued)(VIN= VCTL_= 3.3V, FB = OUT, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETERCONDITIONSMINTYPMAXUNITSSS Source Current-25-20-15µA
SS Sink Current102035µA
SS to GND Resistance in
Shutdown540100Ω
FBSELLow Input Threshold0.3V
High Input ThresholdVIN -
0.3V
Input Bias CurrentFBSEL = GND or IN, VIN = 5.5V-2010+20µA
COMPTransconductance from FB to
COMP406080µS
COMP to GND Resistance in
Shutdown540100Ω
Clamp Voltage Low0.60.91.2V
Clamp Voltage High1.351.752.15V
On-Resistance HighVIN = 3.3V0.230.46Ω
On-Resistance LowVIN = 3.3V0.160.32Ω
Current-Sense Transresistance0.2750.3350.425V/A
Positive Current-Limit Threshold1.11.61.75A
Negative Current-Limit Threshold-1.2-0.8-0.4A
VLX = VIN = 5.5V20LX Shutdown Leakage CurrentLX = GND, VIN = 5.5V-20µA
Switching Frequency1.21.41.6MHz
CTL1, CTL2 (MAX1973), ON (MAX1974)Logic-Low Input Threshold0.6V
Logic-High Input Threshold1.6V
Logic Input Current-1+1µA
POK (MAX1974 only)Output Low VoltagePOK sinking 1mA10100mV
Rising9092.595Output Valid Threshold for POKPercentage of nominal
regulation voltageFalling889092%
MAX1973/MAX1974
Smallest 1A, 1.4MHz Step-Down Regulators
ELECTRICAL CHARACTERISTICS (continued)(VIN= VCTL_= 3.3V, FB = OUT, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETERCONDITIONSMINTYPMAXUNITS
THERMAL SHUTDOWNThermal-Shutdown Threshold+170°C
Thermal-Shutdown Hysteresis20°C
ELECTRICAL CHARACTERISTICS(VIN= VFB= VCTL_= 3.3V, TA
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETERCONDITIONSMINTYPMAXUNITSIN Voltage Range2.65.5V
IN Undervoltage Lockout
ThresholdRising and falling, hysteresis is 25mV (typ)2.22.5V
Supply CurrentSwitching with no load7.5mA
Supply Current in DropoutVOUT set for 3.6V5mA
Shutdown Supply CurrentVIN = 5.5V10µA
MAX19731.25VINOutput Voltage RangeMAX19740.75VINV
FBSEL not connected1.23751.2625
FBSEL = GND1.78201.8180MAX1973
FBSEL = IN2.47502.5250
FBSEL not connected0.74250.7575
FBSEL = GND0.991.01
FB Regulation Voltage
MAX1974
FBSEL = IN1.4851.515
FB Regulation Voltage
Positive Voltage MarginingMAX1973, CTL1 = GND, CTL2 = IN35%
FB Regulation Voltage
Negative Voltage MarginingMAX1973, CTL1 = IN, CTL2 = GND-3-5%
FB Input Resistance to GND in
Preset Output Modes1070kΩ
FB Input Bias CurrentFBSEL not connected-0.15+0.15µA
SS (REFERENCE OUTPUT)SS Source Current-25-15µA
SS Sink Current1035µA
MAX1973/MAX1974
Smallest 1A, 1.4MHz Step-Down Regulators
ELECTRICAL CHARACTERISTICS(VIN= VCTL_= 3.3V, FB = OUT, TA
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETERCONDITIONSMINTYPMAXUNITSSS to GND Resistance
in Shutdown540100Ω
FBSELLow Input Threshold0.3V
High Input ThresholdVIN -
0.4V
Input Bias CurrentFBSEL = GND or IN, VIN = 5.5V-20+20µA
COMPTransconductance
from FB to COMP4080µS
COMP to GND Resistance
in Shutdown5100Ω
Clamp Voltage Low0.61.2V
Clamp Voltage High1.32.2V
On-Resistance HighVIN = 3.3V0.46Ω
On-Resistance LowVIN = 3.3V0.32Ω
Current-Sense Transresistance0.2750.425V/A
Positive Current-Limit Threshold1.101.85A
Negative Current-Limit Threshold-1.20-0.35A
VLX = VIN = 5.5V20LX Shutdown Leakage CurrentLX = GND, VIN = 5.5V-20µA
Switching Frequency1.21.6MHz
CTL1, CTL2 (MAX1973), ON (MAX1974)Logic-Low Input Threshold0.6V
Logic-High Input Threshold1.6V
Logic Input Current-11µA
POK (MAX1974 only)Output Low VoltagePOK sinking 1mA100mV
Rising9095Output Valid Threshold
for POK
Percentage of nominal
regulation voltageFalling8892%
Note 2:Specifications to -40°C are guaranteed by design and not production tested.
MAX1973/MAX1974
Smallest 1A, 1.4MHz Step-Down Regulators
Typical Operating Characteristics(Circuits of Figure 2, 3, and 4; TA= +25°C, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
MAX1973/74 toc01
LOAD CURRENT (A)
EFFICIENCY (%)40
VOUT = 2.5V
VOUT = 1V
VOUT = 1.8V
VIN = 3.3V
EFFICIENCY vs. LOAD CURRENT
MAX1973/74 toc02
LOAD CURRENT (A)
EFFICIENCY (%)40
VOUT = 3.3V
VOUT = 2.5V
VIN = 5V
DROPOUT VOLTAGE vs. LOAD CURRENT
MAX1973/74 toc03
LOAD CURRENT (A)
DROPOUT VOLTAGE (V)0.20.40.60.8
VOUT = 3.3V
VOUT = 2.5V1345
NO-LOAD CURRENT vs. INPUT VOLTAGEMAX1973/74 toc04
INPUT VOLTAGE (V)
NO-LOAD CURRENT (mA)
VOUT = 2.5V
FB VOLTAGE vs. LOAD CURRENT
MAX1973/74 toc05
LOAD CURRENT (A)
FB VOLTAGE (V)
MAX1973
VIN = 5V
R1 = 22kΩ
R2 = 13kΩ
CHANGE IN OUTPUT VOLTAGE
vs. LOAD CURRENT
MAX1973/74 toc06
LOAD CURRENT (A)
CHANGE IN OUTPUT VOLTAGE (mV)
VIN = 5V
VOUT = 1.8V
2.5V
SWITCHING FREQUENCY
vs. SUPPLY VOLTAGE
MAX1973/74 toc07
SUPPLY VOLTAGE (V)
SWITCHING FREQUENCY (MHz)
TA = +85°C
TA = +25°C
TA = -40°C
VIN = 5V, 100kΩ PULLUP RESISTOR POK TO VOUT
MAX1974
STARTUP WAVEFORMSPOK
VOUT1V/div
10V/div
2V/div
MAX1973/74 toc08
IIN
200mA/div
MAX1973/MAX1974
Smallest 1A, 1.4MHz Step-Down RegulatorsVIN = 5V, VOUT = 2.5V, IOUT = 800mA
MAX1973
HIGH-CURRENT SWITCHING WAVEFORMSVLX
VOUT
5V/div
20mV/div
MAX1973/74 toc09
500mA/div
500ns/div
VIN = 5V, VOUT = 2.5V, IOUT = 10mA
MAX1973
LOW-CURRENT SWITCHING WAVEFORMSVLX
VOUT
5V/div
20mV/div
MAX1973/74 toc10
500mA/div
500ns/div
VIN = 5V, VOUT = 2.5V, IOUT = 400mA TO 800mA
MAX1973
LOAD TRANSIENTVOUT
20mV/div
MAX1973/74 toc11
500mA/div
500ns/div
VIN = 5V, VOUT = 2.5V, IOUT = 600mA TO 800mA
MAX1973
LOAD TRANSIENTVOUT
200mV/div
MAX1973/74 toc12
500mA/div
20μs/div
VIN = 3.3V TO 5V TO 3.3V, IOUT = 800mA
MAX1973
LINE TRANSIENTVOUT
VIN
50mV/div
MAX1973/74 toc13
2V/div
200μs/div
ypical Operating Characteristics (continued)(Circuits of Figure 2, 3, and 4; TA= +25°C, unless otherwise noted.)
MAX1973/MAX1974
Smallest 1A, 1.4MHz Step-Down Regulators
Pin Description
NAMEPINMAX1973MAX1974FUNCTIONFBSELFBSEL
Feedback-Mode Selector. Connect FBSEL to GND to set the output voltage to 1.8V
(MAX1973) or 1V (MAX1974). Connect FBSEL to IN to set the output voltage to 2.5V
(MAX1973) or 1.5V (MAX1974). Leave FBSEL unconnected to set the output voltage
using a resistor-divider at FB.COMPCOMP
Compensation. Connect a series RC network to GND. COMP is internally pulled to
GND when the device is in shutdown or in undervoltage lockout (see the Compen-
sation Components section).
3FBFBFeedback Input. Connect to the output if a preset voltage is used, or to a resistor-
divider from the output to GND for an adjustable output voltage.
4SSSS
Soft-Start Pin and Reference Output. Bypass to GND with at least 0.01µF. Connect
0.1µF to GND for a soft-start ramp time of 6.25ms for the MAX1973, or 3.75ms for the
MAX1974. SS is internally pulled to GND when the device is shut down or in
undervoltage lockout.GNDGNDGround
CTL2—Control Input 2. Controls enable/disable and voltage margining (see Table 1).—POKPower-OK Output. Open-drain output goes low when output is below 90% of nominal
output. POK is also low when the device is shut down or in undervoltage lockout.PGNDPGNDPower GroundLXLXInductor Connection. Connect an inductor from LX to the output.
9ININInput Supply Voltage. Input voltage range is 2.6V to 5.5V. Connect a 4.7µF capacitor
from IN to PGND.
CTL1—Control Input 1. Controls Enable/Disable and voltage margining (see Table 1).—ONEnable Input. Connect to IN or drive high for normal operation. Drive low to put device
in shutdown.
MAX1974 WITH 100kΩ PULLUP RESISTOR
FROM POK TO IN, ILOAD = 100mA
MAX1974
POK AND INPUT VOLTAGEVPOK
2V/div
MAX1973/74 toc15
20ms/div
VIN
1V/divVOUT
2V/div
VIN = 5V, VOUT = 2.5V, IOUT = 800mA, -4% TO +4% TO -4%
MAX1973
VOLTAGE MARGIN STEP CHANGE RESPONSEVOUT
IIN
1V/div
MAX1973/74 toc14
500mA/div
1ms/div
VCTL1
VCTL2
10V/div
10V/div
ypical Operating Characteristics (continued)(Circuits of Figure 2, 3, and 4; TA= +25°C, unless otherwise noted.)
