MAX1639ESE+T ,High-Speed Step-Down Controller with Synchronous Rectification for CPU Powerapplications in which♦ Greater than 90% Efficiency Using N-Channeloutput voltage precision and good ..
MAX1639ESE+T ,High-Speed Step-Down Controller with Synchronous Rectification for CPU PowerApplicationsLocal DC-DC Converters for CPUsINPUT+5VWorkstationsVV DDCCDesktop ComputersAGND BSTLAN ..
MAX163BCNG ,CMOS 12-Bit A/D Converters With Track-and-HoldELECTRICAL CHARACTERISTICS
(VDD = +5V i5%, Vss = -11.4V to -15.75V, Slow Memory Mode (see text), ..
MAX163BCWG ,CMOS 12-Bit A/D Converters With Track-and-HoldFeatures
. 12-Bit Resolution
. 8.33ps Conversion Time
. Internal Analog Track-Hold
. 6MHz Full ..
MAX163CCNG+ ,CMOS, 5V Input, 100ksps, 12-Bit ADC with Track/Hold and ReferenceApplications
Digital Signal Processing (DSP)
Audio and Telecom Processing
High Accuracy Proces ..
MAX163CCNG+ ,CMOS, 5V Input, 100ksps, 12-Bit ADC with Track/Hold and ReferenceApplications
Digital Signal Processing (DSP)
Audio and Telecom Processing
High Accuracy Proces ..
MAX4385EEUK+T ,Low-Cost, 230MHz, Single/Quad Op Amps with Rail-to-Rail Outputs and ±15kV ESD ProtectionELECTRICAL CHARACTERISTICS (V = 5V, V = 0, V = V /2, V = V /2, R = ∞ to V /2, C = 2.2µF, T = T to T ..
MAX4386EESD ,Low-Cost / 230MHz / Single/Quad Op Amps with Rail-to-Rail Outputs and 15kV ESD ProtectionApplications Ultra-Small 5-Pin SOT23 and 14-Pin TSSOPSet-Top Boxes CCD Imaging PackagesSystemsSurv ..
MAX4386EEUD+T ,Low-Cost, 230MHz, Single/Quad Op Amps with Rail-to-Rail Outputs and ±15kV ESD ProtectionApplications♦ Ultra-Small 5-Pin SOT23 and 14-Pin TSSOPPackagesSet-Top Boxes CCD ImagingSystemsSurve ..
MAX4389EUT ,Ultra-Small, Low-Cost, 85MHz Op Amps with Rail-to-Rail Outputs and DisableMAX4389/MAX4390/ Ultra-Small, Low-Cost, 85MHz Op Amps withMAX4392–MAX4396 Rail-to-Rail Outputs and ..
MAX4389EUT+T ,Ultra-Small, Low-Cost, 85MHz Op Amps with Rail-to-Rail Outputs and DisableElectrical Characteristics—Single Supply(V = 5V, V = 0V, V = V /2, V = V /2, R = ∞ to V /2, DISABLE ..
MAX4390EUK ,Ultra-Small, Low-Cost, 85MHz Op Amps with Rail-to-Rail Outputs and DisableElectrical Characteristics—Single Supply (continued)(V = 5V, V = 0V, V = V /2, V = V /2, R = ∞ to V ..
MAX1639ESE+-MAX1639ESE+T
High-Speed Step-Down Controller with Synchronous Rectification for CPU Power
________________General DescriptionThe MAX1639 is an ultra-high-performance, step-down
DC-DC controller for CPU power in high-end computer
systems. Designed for demanding applications in which
output voltage precision and good transient response are
critical for proper operation, it delivers over 35A from 1.1V
to 4.5V with ±1% total accuracy from a +5V ±10% supply.
Excellent dynamic response corrects output transients
caused by the latest dynamically clocked CPUs. This
controller achieves over 90% efficiency by using synchro-
nous rectification. Flying-capacitor bootstrap circuitry
drives inexpensive, external N-channel MOSFETs.
The switching frequency is pin-selectable for 300kHz,
600kHz, or 1MHz. High switching frequencies allow the
use of a small surface-mount inductor and decrease out-
put filter capacitor requirements, reducing board area
and system cost.
Output overvoltage protection is enforced by a crowbar
circuit that turns on the low-side MOSFET with 100%
duty factor when the output is 200mV above the normal
regulation point. Other features include internal digital
soft-start, a power-good output, and a 3.5V ±1% refer-
ence output. The MAX1639 is available in a 16-pin
narrow SOIC package.
________________________ApplicationsLocal DC-DC Converters for CPUs
Workstations
Desktop Computers
LAN Servers
GTL Bus Termination
____________________________FeaturesBetter than ±1% Output Accuracy Over
Line and LoadGreater than 90% Efficiency Using N-Channel
MOSFETsPin-Selected High Switching Frequency:
300kHz, 600kHz, or 1MHzOver 35A Output CurrentResistor-Divider Adjustable Output from
1.1V to 4.5VCurrent-Mode Control for Fast Transient
Response and Cycle-by-Cycle Current-Limit
ProtectionShort-Circuit Protection with Foldback Current
LimitingCrowbar Overvoltage ProtectionPower-Good (PWROK) OutputDigital Soft-StartHigh-Current (2A) Drive Outputs
MAX1639
High-Speed Step-Down Controller with
Synchronous Rectification for CPU Power19-1337; Rev 1; 8/05
_______________Ordering Information
__________Typical Operating Circuit
Pin Configuration appears at end of data sheet.VCC
AGND
REF
FREQ
CC1
CC2
PWROK
BST
PGND
TO VDD
CSH
OUTPUT
1.1V TO 4.5V
INPUT
+5V
VDD
CSL
MAX1639
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET+Denotes lead-free packages.
PARTTEMP RANGEPIN-PACKAGEMAX1639ESE40°C to +85°C16 Narrow SO
MAX1639ESE+40°C to +85°C16 Narrow SO
FREQ Input Voltage
MAX1639
High-Speed Step-Down Controller with
Synchronous Rectification for CPU Power
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VDD= VCC= +5V, PGND = AGND = 0V, FREQ = REF, 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.
VDD, VCC, PWROK to AGND....................................-0.3V to +6V
PGND to AGND..................................................................±0.3V
CSH, CSL to AGND....................................-0.3V to (VCC+ 0.3V)
DL to PGND................................................-0.3V to (VDD+ 0.3V)
REF, CC1, CC2, FREQ, FB to AGND.........-0.3V to (VCC + 0.3V)
BST to PGND..........................................................-0.3V to +12V
BST to LX..................................................................-0.3V to +6V
DH to LX.............................................(LX - 0.3V) to (BST + 0.3V)
Continuous Power Dissipation (TA= +70°C)
16-Pin Narrow SO (derate 8.70mW/°C above +70°C)....696mW
SO θJC...........................................................................65°C/W
Operating Temperature Range
MAX1639ESE....................................................-40°C to +85°C
Storage Temperature Range.............................-65°C to +160°C
Lead Temperature (soldering, 10s).................................+300°C
FREQ = AGND
FREQ = REF
VCC= VDD
FREQ = VCC
PWROK = 5.5V
Includes line and load
regulation errors
ISINK= 2mA, VCC= 4.5V
Falling FB, 1% hysteresis with respect to VREF
Rising FB, 1% hysteresis with respect to VREF
0µA < IREF< 100µA
No load
VCC= VDD= 5.5V, FB forced 60mV above
regulation point, operating or standby mode
VCCrising edge, 1% hysteresis
VREF= 0V
Rising edge, 1% hysteresis
CONDITIONSkHz
Switching Frequency540600660
850100011501PWROK Output Current High0.4PWROK Output Voltage Low6.589.5PWROK Trip Level-7.5-6-4.50.54.0Reference Short-Circuit Current2.73.0Reference Undervoltage Lockout4.55.5Input Voltage Range1.0831.117
1.0891.111FB Voltage10Reference Load Regulation3.4653.53.535Reference Voltage0.1VDDSupply Current (IDD)4.04.2Input Undervoltage Lockout
UNITSMINTYPMAXPARAMETER= +25°C to +85°C= 0°C to +85°C
CSH - CSL = 0mV to 80mV%1AC Load Regulation
CSH - CSL = 0mV to 80mV%0.1DC Load Regulation
FB overdrive = 60mV
FB overdrive = 0V
Operating
mode
VCC= VDD
= 5.5V
VREF= 0VShutdown
mode
VCCSupply Current (ICC)
VCC(high)
GND (low)
FREQ = VCC%
VCC- 0.1
Maximum Duty Cycle
FREQ Input VoltageVREF (mid)3.33.7
ELECTRICAL CHARACTERISTICS (continued)(VDD= VCC = +5V, PGND = AGND = 0V, FREQ = REF, TA
= 0°C to +85°C, unless otherwise noted.)
MAX1639
High-Speed Step-Down Controller with
Synchronous Rectification for CPU Power3870mVFB = 0V (foldback)Current-Limit Trip Voltage
DL On-ResistanceΩµABST = 12V, LX = 7V, REF = GNDBST Leakage Current
15361 / fOSCTo full current limitSoft-Start Time100115FB = 1.1V
FB Input Current
CC2 Clamp Voltage
PARAMETERMINTYPMAXUNITSFREQ Input Current4µA
±0.1µA
2.43.0V4VCC
CC2 Source/Sink Current100µA
0.72DH On-Resistance
Maximum
DH, DL Source/Sink Current2A
DH, DL Dead Time030ns
CONDITIONSMinimum
30mV overdrive
BST - LX = 4.5V
VDD= 4.5V
DH = DL = 2.5V
ELECTRICAL CHARACTERISTICS (VDD= VCC= +5V, PGND = AGND = 0V, FREQ = REF, TA
= -40°C to +85°C, unless otherwise noted.) (Note 1)
Note 1:Specifications from 0°C to -40°C are guaranteed by design, not production tested.
FREQ = REF
FREQ = VCC
BST - LX = 4.5V
FREQ = VCC
Falling FB, 1% hysteresis with respect to VREF
Rising FB, 1% hysteresis with respect to VREF
FREQ = AGND
VDD= 4.5V284
DL On-Resistance
VCCrising edge, 1% hysteresis
VCC= VDD
CONDITIONSMaximum Duty Cycle
DH On-Resistance
Switching Frequency
FB = 1.1VCurrent-Limit Trip VoltagemV70130
kHz
240360-8-4PWROK Trip Level3.94.3Input Undervoltage Range4.55.5Input Voltage Range
UNITSMINTYPMAXPARAMETERCC2 Transconductance
CC1 Output Resistance10kΩmmho
CSH, CSL Input Current50µACSH = CSL = 1.1V
VCC= VDD=
5.5VmA12VDDSupply Current3
Includes line and load regulation errors
No load1.0721.128FB Voltage 3.4483.553Reference Voltage
VCC= VDD= 5.5V, FB forced 60mV above
regulation point, operating or shutdown modemA0.2VDDSupply Current
Operating modeFB overdrive = 60mV
VREF = 0VShutdown mode
MAX1639
High-Speed Step-Down Controller with
Synchronous Rectification for CPU Power
FOLDBACK CURRENT LIMIT
(VOUT = 2.5V, NOMINAL)MAX1639-02
A: VOUT = 0.5V/div
B: INDUCTOR CURRENT, 5A/div
10μs/div
STARTUP WAVEFORMSMAX1639-03
A: INDUCTOR CURRENT, 2A/div
B: VOUT = 1V/div
400μs/div
1μs/div
SWITCHING WAVEFORMSMAX1639-04
VIN = 5V, VOUT = 2.5V, LOAD = 0A
A: VOUT, 20mV/div
B: INDUCTOR CURRENT, 2A/div
C: LX, 5V/div
LOAD-TRANSIENT RESPONSE
(VOUT = 2.5V)MAX1639-01
VIN = 5V, VOUT = 2.5V, LOAD = 8A
A: VOUT, 100mV/div, AC COUPLED
B: INDUCTOR CURRENT, 5A/div
10μs/div
__________________________________________Typical Operating Characteristics(TA = +25°C, using the MAX1639 evaluation kit, unless otherwise noted.)
EFFICIENCY vs. OUTPUT CURRENT
MAX1639-05
OUTPUT CURRENT (A)
EFFICIENCY (%)
3.5V
1.8V
2.5V
MAXIMUM DUTY CYCLE
vs. SWITCHING FREQUENCYMAX1639-06
SWITCHING FREQUENCY (kHz)
MAXIMUM DUTY CYCLE (%)
600400
MAX1639
High-Speed Step-Down Controller with
Synchronous Rectification for CPU Power
______________________________________________________________Pin DescriptionAnalog GroundAGNDReference Output, 3.5V. Bypass REF to AGND with 0.1µF (min). Sources up to 100µA for external
loads. Force REF below 2V to turn off the controller. REFAnalog Supply Input, 5V. Use an RC filter network, as shown in Figure 1. VCCCurrent-Sense Amplifier’s Noninverting InputCSHCurrent-Sense Amplifier’s Inverting Input. Place the current-sense resistor very close to the controller IC,
and use a Kelvin connection.CSLOpen-Drain Logic Output. PWROK is high when the voltage on FB is within +8% and -6% of its set-
point. PWROKVoltage-Feedback Input. The voltage at this input is regulated to 1.100V.FBFast-Loop Compensation Capacitor Input. Connect a ceramic capacitor and resistor in series from
CC1 to AGND. See the section Compensating the Feedback Loop.CC1
FUNCTIONNAMEBoost-Capacitor Bypass for High-Side MOSFET Gate Drive. Connect a 0.1µF capacitor and low-leak-
age Schottky diode as a bootstrapped charge-pump circuit to derive a 5V gate drive from VDDfor DH.BSTSlow-Loop Compensation Capacitor Input. Connect a ceramic capacitor from CC2 to AGND. See the
section Compensating the Feedback Loop.CC2
Frequency-Select Input.FREQ = VCC: 1MHz
FREQ = REF: 600kHz
FREQ = AGND: 300kHz
FREQPower Input for MOSFET Drivers, 5V. Bypass VDDto PGND within 0.2 in. (5mm) of the VDDpin using a
0.1µF capacitor and 4.7µF capacitor connected in parallel. VDDLow-Side Synchronous Rectifier Gate-Drive Output. DL swings between PGND and VDD. See the
section BST High-Side Gate-Driver Supply and MOSFET Drivers.DLPGNDPower GroundLXSwitching Node. Connect LX to the high-side MOSFET source and inductor.DH
High-Side Main MOSFET Switch Gate-Drive Output. DH is a floating driver output that swings from LX
to BST, riding on the LX switching-node voltage. See the section BST High-Side Gate-Driver Supply
and MOSFET Drivers.
PIN
MAX1639
High-Speed Step-Down Controller with
Synchronous Rectification for CPU Power(OPTIONAL)
(OPTIONAL)
(OPTIONAL)
VCCVDD
PWROKBST
PGND
CSH
AGNDR8
CC1
CC2
CC1
1000pF
CC2
0.056μF
REF
C4, 1.0μF
CERAMIC
RC1TO
AGND
100k
0.1μF
10μF
10Ω
TO VDD
FREQ
0.1μF
CMPSH-3
0.1μF
VIN = 4.5V
TO 5.5V
MAX1639
VOUT = 1.1V
TO 4.5V
CSL
Figure 1. Standard Application Circuit
_______Standard Application CircuitsThe predesigned MAX1639 circuit shown in Figure 1
meets a wide range of applications with output currents
up to 35A. Use Table 1 to select components appropri-
ate for the desired output current range, and adapt the
evaluation kit PC board layout as necessary. This cir-
cuit represents a good set of trade-offs between cost,
size, and efficiency while staying within the worst-case
specification limits for stress-related parameters, such
as capacitor ripple current.
The MAX1639 circuit was designed for the specified fre-
quencies. Do not change the switching frequency with-
out first recalculating component values—particularly
the inductance, output filter capacitance, and RC1
resistance values.
___________________Detailed DescriptionThe MAX1639 is a BiCMOS power-supply controller
designed for use in switch-mode, step-down (buck)
topology DC-DC converters. Synchronous rectification
provides high efficiency. It is intended to provide the
high precision, low noise, excellent transient response,
and high efficiency required in today’s most demand-
ing applications.
MAX1639
High-Speed Step-Down Controller with
Synchronous Rectification for CPU Power
Table 1. Component List for Standard Applications (x5) 560µF, Sanyo OS-CON 4SP560M
Central Semiconductor CMPSH-3
0.3µH, 25A, 0.9mΩ
Panasonic ETQPAF0R3E
(x2) 7mΩ, Dale WSL-2512-R007-J
(x3) 330µF, Sanyo OS-CON 6SA330M
LOAD REQUIREMENTSchottky diode, Motorola MBRD640
(x2) 0.010Ω, 30V, D2PAK, Fairchild FDB7030L
(x2) 0.014Ω, 30V, SO8, Fairchild FDS6680
(x2) 0.010Ω, 30V, D2PAK, Fairchild FDB7030L
(x2) 0.014Ω, 30V, SO8, Fairchild FDS6680
1.8V, 20A(x2) 560µF, Sanyo OS-CON 4SP560M
Central Semiconductor CMPSH-3
1.0µH, 9.3A, SMD
Coiltronics UP2B-1R01.0µH, 10A, SMD
Coilcraft D03316P-102HC
9mΩDale,
WSL-2512-R009-J
330µF, Sanyo OS-CON 6SA330M D1 (optional)Schottky diode, Nihon NSQ03A02
0.014Ω, 30V, SO8
Fairchild FDS66800.018Ω, 30V, SO8
International Rectifier IRF7413
0.014Ω, 30V, SO8
Fairchild FDS66800.018Ω, 30V, SO8
International Rectifier IRF7413
2.5V, 8A
COMPONENT
Note:Parts used in evaluation board are shown in bold.
PWM Controller Block and IntegratorThe heart of the current-mode PWM controller is a
multi-input, open-loop comparator that sums three sig-
nals (Figure 2): the buffered feedback signal, the cur-
rent-sense signal, and the slope-compensation ramp.
This direct-summing configuration approaches ideal
cycle-by-cycle control over the output voltage. The out-
put voltage error signal is generated by an error ampli-
fier that compares the amplified feedback voltage to an
internal reference.
Each pulse from the oscillator sets the main PWM latch
that turns on the high-side switch for a period deter-
mined by the duty factor (approximately VOUT/ VIN). The
current-mode feedback system regulates the peak
inductor current as a function of the output voltage error
signal. Since average inductor current is nearly the same
as peak current (assuming the inductor value is set rela-
tively high to minimize ripple current), the circuit acts as
a switch-mode transconductance amplifier. It pushes the
second output LC filter pole, normally found in a duty-
factor-controlled (voltage-mode) PWM, to a higher fre-
quency. To preserve inner-loop stability and eliminate
regenerative inductor current staircasing, a slope-
compensation ramp is summed into the main PWM com-
parator. Under fault conditions where the inductor cur-
rent exceeds the maximum current-limit threshold, the
high-side latch resets, and the high-side switch turns off.
Internal ReferenceThe internal 3.5V reference (REF) is accurate to ±1%
from 0°C to +85°C, making REF useful as a system ref-
erence. Bypass REF to AGND with a 0.1µF (min)
ceramic capacitor. A larger value (such as 2.2µF) is
recommended for high-current applications. Load reg-
ulation is 10mV for loads up to 100µA. Reference
undervoltage lockout is between 2.7V and 3V. Short-
circuit current is less than 4mA.
Synchronous-Rectifier DriverSynchronous rectification reduces conduction losses in
the rectifier by shunting the normal Schottky diode or
MOSFET body diode with a low-on-resistance MOSFET
switch. The synchronous rectifier also ensures proper
start-up by precharging the boost-charge pump used
for the high-side switch gate-drive circuit. Thus, if you
must omit the synchronous power MOSFET for cost or
other reasons, replace it with a small-signal MOSFET,
such as a 2N7002.
The DL drive waveform is simply the complement of the
DH high-side drive waveform (with typical controlled
dead time of 30ns to prevent cross-conduction or
shoot-through). The DL output’s on-resistance is 0.7Ω
(typ) and 2Ω(max).
10.0kΩ, 1%
10.0kΩ, 1%R7
6.19kΩ, 1%
12.7kΩ, 1%R8
