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General Description

The MAX8513/MAX8514 integrate a voltage-mode

PWM step-down DC-DC controller and two LDO con-

trollers, a voltage monitor, and a power-on reset for the

lowest-cost power-supply and monitoring solution for

xDSL modems, routers, gateways, and set-top boxes.

The DC-DC controller switching frequency can be set

with an external resistor from 300kHz to 1.4MHz, to allow

for the optimization of cost, size, and efficiency. For noise-

sensitive applications, the DC-DC controller can also be

synchronized to an external clock, minimizing noise inter-

ference. Operation above 1.1MHz reduces noise for high

data-rate xDSL applications. An adjustable soft-start and

adjustable foldback current limit provide reliable startup

and fault protection. The DC-DC controller output voltage

can be set externally to a voltage from 1.25V to 5.5V.

Current limiting is accomplished by inductor current sens-

ing for improved efficiency, or by an external sense resis-

tor for better accuracy.

The MAX8513/MAX8514s’ first LDO controller is

designed to provide a low-cost, high-current regulated

output from 0.8V to 5.5V using an N-channel MOSFET or

a low-current output using a low-cost NPN transistor. The

MAX8513’s second regulator can be used to generate

0.8V to 27V output with a low-cost PNP transistor. Both

LDO regulators can operate either from the DC-DC con-

troller output or from a higher voltage derived with a fly-

back overwinding on the DC-DC converter inductor. The

MAX8514’s second LDO regulator is designed to pro-

vide a negative output with an NPN transistor.

A sequence input allows the outputs to either power up

together, or for the DC-DC regulator to power up first

and each LDO controller to power up in sequence. An

input power-fail output (PFO) is provided for input

power-fail warning, such as in dying-gasp applications.

A power-on reset circuit with a 140ms delay is also

included to indicate when all outputs have achieved

regulation and stabilized.

Applications

xDSL, Cable, ISDN Modems, and Routers

Wireless Routers

Set-Top Boxes

Automotive Dashboard Electronics

Features

♦ Low-Cost DC-DC Controller with Two LDOs

♦ Wide Input Range: 4.5V to 28V

♦ 300kHz to 1.4MHz Adjustable Switching

Frequency

♦ Low Noise for High Data-Rate xDSL Applications

♦ Synchronizable to External Clock

♦ Adjustable Soft-Start

♦ Lossless Adjustable Foldback Current Limit

♦ Power-On Reset with 140ms Delay

♦ Adjustable Input Power-Fail Warning for Dying

Gasp

♦ Selectable Output-Voltage Sequencing or

Output-Voltage Tracking

MAX8513/MAX8514

Wide-Input, High-Frequency, Triple-Output Supplies

with Voltage Monitor and Power-On Reset

________________________________________________________________ Maxim Integrated Products 1

STEP-

DOWN

CONTROLLER

(4.5V TO 28V)

OUT1

(1.25V TO 5.5V)

OUT2

(0.8V TO V

OUT1

)

OUT3

(0.8V TO 27V)

LDO

CONTROLLER 1

LDO

CONTROLLER 2

OUTPUT

POWER-ON RESET

INPUT POWER-

FAIL MONITOR

MAX8513

SYNC

OFF

Functional Diagram

Ordering Information

19-3178; Rev 0; 2/04

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

EVALUATION KIT

AVAILABLE

PART TEMP RANGE PIN-PACKAGE

MAX8513EEI -40°C to +85°C 28 QSOP

MAX8514EEI -40°C to +85°C 28 QSOP

MAX8514AEI -40°C to +125°C 28 QSOP

Pin Configurations appear at end of data sheet.

Summary of content (35 pages)

PAGE 1
9-3178; Rev 0; 2/04 KIT ATION EVALU E L B A AVAIL Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset A sequence input allows the outputs to either power up together, or for the DC-DC regulator to power up first and each LDO controller to power up in sequence. An input power-fail output (PFO) is provided for input power-fail warning, such as in dying-gasp applications.
PAGE 2
MAX8513/MAX8514 Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset ABSOLUTE MAXIMUM RATINGS IN, DRV3P, SUP2 to GND.......................................-0.3V to +30V DRV2 to GND ..........................................-0.3V to (VSUP2 + 0.3V) DRV3N to GND......................(VSUP3N - 28V) to (VSUP3N + 0.3V) FREQ, PFI, PFO, POR, SUP3N, SYNC/EN, CSP, CSN to GND ................................................-0.3V to +6V VL to GND ...................-0.
PAGE 3
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset (VIN = VLX = VSUP2 = 12V, VPVL = VBST - VLX = VDRV3P = 5V, VSUP3N = 3.3V, VDRV3N = -5V, CVL = 4.7µF, CREF = 0.22µF, RFREQ = 15.0kΩ, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Current-Limit Threshold (Positive) Current-Limit Threshold (Negative) SYMBOL VCS VCS MIN TYP MAX VILIM = 2.00V, VCSN = 0 to 5.5V CONDITIONS 246 275 300 VILIM = 0.50V, VCSN = 0 to 5.
PAGE 4
MAX8513/MAX8514 Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset ELECTRICAL CHARACTERISTICS (continued) (VIN = VLX = VSUP2 = 12V, VPVL = VBST - VLX = VDRV3P = 5V, VSUP3N = 3.3V, VDRV3N = -5V, CVL = 4.7µF, CREF = 0.22µF, RFREQ = 15.0kΩ, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS OUT3N (NEGATIVE NPN LDO CONTROLLER) (MAX8514 ONLY) SUP3N Operating Range (Note 1) 1.5 5.
PAGE 5
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset (VIN = VLX = VSUP2 = 12V, VPVL = VBST - VLX = VDRV3P = 5V, VSUP3N = 3.3V, VDRV3N = -5V, CVL = 4.7µF, CREF = 0.22µF, RFREQ = 15.0kΩ, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS SEQ, PFI, PFO, POR SEQ Input-Voltage High 2.4 V SEQ Input-Voltage Low 0.8 V 1 10 µA IPOR = 1.6mA 10 200 IPOR = 0.1mA, VIN = 1.0V 20 200 0.
PAGE 6
MAX8513/MAX8514 Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset ELECTRICAL CHARACTERISTICS (continued) (VIN = VLX = VSUP2 = 12V, VPVL = VBST - VLX = VDRV3P = 5V, VSUP3N = 3.3V, VDRV3N = -5V, CVL = 4.7µF, CREF = 0.22µF, RFREQ = 15.0kΩ, TA = -40°C to +125°C (Note 2), unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN MAX UNITS OUT1 (BUCK CONVERTER) Output Voltage Range 1.25 5.50 V FB1 Regulation Threshold VOUT1 VFB1 (Note 1) 1.225 1.
PAGE 7
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset (VIN = VLX = VSUP2 = 12V, VPVL = VBST - VLX = VDRV3P = 5V, VSUP3N = 3.3V, VDRV3N = -5V, CVL = 4.7µF, CREF = 0.22µF, RFREQ = 15.0kΩ, TA = -40°C to +125°C (Note 2), unless otherwise noted.
PAGE 8
MAX8513/MAX8514 Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset ELECTRICAL CHARACTERISTICS (continued) (VIN = VLX = VSUP2 = 12V, VPVL = VBST - VLX = VDRV3P = 5V, VSUP3N = 3.3V, VDRV3N = -5V, CVL = 4.7µF, CREF = 0.22µF, RFREQ = 15.0kΩ, TA = -40°C to +125°C (Note 2), unless otherwise noted.) PARAMETER SYMBOL CONDITIONS SYNC/EN Input-Voltage High MIN SYNC/EN Input-Voltage Low SYNC/EN Input Current MAX UNITS 0.8 V +1 µA 2.4 VSYNC/EN = 0 to 5.
PAGE 9
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset EFFICIENCY vs. IOUT1 (IOUT2 = 0, IOUT3 = 0) 90 80 40 30 VOUT1 = 3.3V, IOUT1 = 2A VOUT2 = 2.5V, IOUT2 = 1.5A VOUT3 = 12V, IOUT3 = 50mA 20 10 0 7 VIN = 12V 50 40 VIN = 16V 20 3.27 10 3.26 3.25 0.1 0.6 VOUT2 vs. IOUT2 1.1 1.6 2.1 2.6 3.1 3.6 0 4.1 12.20 12.15 VOUT1 (V) 3.31 VOUT3 (V) 3.32 12.00 3.29 2.48 11.90 3.28 2.47 11.85 11.80 2.45 11.75 0.6 0.8 1.0 3.27 VOUT1 = 3.
PAGE 10
MAX8513/MAX8514 Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset Typical Operating Characteristics (continued) (Circuit of MAX8513 evaluation kit, VIN = 12V, TA = +25°C, fS = 1.4MHz, unless otherwise noted.) OUTPUT1 LOAD-TRANSIENT RESPONSE OUTPUT3 LOAD-TRANSIENT RESPONSE MAX8513/14 toc10 MAX8513/14 toc11 IOUT2 = 0.75A, IOUT3 = 25mA IOUT1 = 1A, IOUT2 = 0.
PAGE 11
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset STAGGERED SEQUENCE (SEQ = GND) TRACKING SEQUENCE (SEQ = VL) MAX8513/14 toc16 MAX8513/14 toc17 SYNC/EN 5V/div 0V SYNC/EN 5V/div 0V VOUT3 5V/div VOUT1 2V/div VOUT2 2V/div VOUT3 5V/div VOUT1 2V/div VOUT2 2V/div 0V 0V 2ms/div 4ms/div OUTPUT1 SHORT CIRCUIT (ALL OUTPUTS AT FULL LOAD) OUTPUT1 SHORT CIRCUIT (ALL OUTPUTS AT NO LOAD) MAX8513/14 toc18 MAX8513/14 toc19 VOUT1 2V/div VOUT1 2V/div 0V 0V VLX 10V/
PAGE 12
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset MAX8513/MAX8514 Pin Description 12 PIN NAME MAX8513 MAX8514 PFI 1 1 Power-Fail Input. Connect PFI to an external resistive-divider between IN, PFI, and GND. PFI senses VIN to detect voltage failure. Trip falling threshold at this input is 1.22V, with 20mV of hysteresis. PFO 2 2 Power-Fail Output. Open-drain output that goes low if VPFI < 1.22V. DH 3 3 OUT1 High-Side Gate-Drive Output.
PAGE 13
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset PIN NAME MAX8513 MAX8514 SEQ 18 18 Connect to VL for output tracking. Connect to GND for output staggered sequence. Staggered sequence ramps up VOUT2 and VOUT3 softly to avoid glitches on the previous voltage due to charging of the LDO’s output capacitors. FUNCTION SYNC/EN 19 19 Shutdown Control and Synchronization Input.
PAGE 14
MAX8513/MAX8514 Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset IN SS BST SYNC/EN S Q DH R Q LX PVL VL BIAS 1/7.5 DL 5µA PGND GND CSP FREQ PWM COMP. SEQ CSN 1VP-P FB1 ERROR AMP PFI COMP 1.25V PFO N ILIM SUP2 0.8V POR DRV2 GC2 N FB2 0.8V GC3P REF REFERENCE DRV3P N N FB3P MAX8513 Figure 1.
PAGE 15
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset MAX8513/MAX8514 IN SS BST SYNC/EN S Q DH R Q LX PVL VL BIAS 1/7.5 DL 5µA GND PGND CSP FREQ PWM COMP. SEQ CSN 1VP-P FB1 ERROR AMP PFI COMP 1.25V PFO N ILIM SUP2 REFERENCE 0.8V POR DRV2 GC2 N FB2 SUP3N P REF GC3N P DRV3N FB3N MAX8514 Figure 2.
PAGE 16
MAX8513/MAX8514 Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset Detailed Description The MAX8513/MAX8514 combine a step-down DC-DC converter and two LDOs, providing three output voltages for xDSL modem and set-top box applications. The switching frequency is set with an external resistor connected from the FREQ pin to GND, and is adjustable from 300kHz to 1.4MHz.
PAGE 17
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset Undervoltage Lockout If V VL drops below 3.8V, the MAX8513/MAX8514 assume that the supply voltage is too low to make valid decisions. When this happens, the undervoltage lockout (UVLO) circuitry inhibits switching, forces POR and PFO low, and forces DL and DH gate drivers low. After VVL rises above 3.9V, the controller powers up the outputs (see the Startup section).
PAGE 18
MAX8513/MAX8514 Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset Thermal-Overload Protection Thermal-overload protection limits the total power dissipation in the MAX8513/MAX8514. When the junction temperature exceeds TJ = +170°C, a thermal sensor shuts down the device, forcing DL and DH low and allowing the IC to cool.
PAGE 19
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset It is important to have the secondary winding tightly coupled with the primary winding to minimize leakage inductance for higher efficiency. The positive voltage generated by the secondary winding can also be stacked with the main DC-DC step-down converter output to further improve efficiency and reduce winding cost.
PAGE 20
MAX8513/MAX8514 Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset The peak-to-peak output voltage ripple as a consequence of the ESR, ESL, and output capacitance is: VRIPPLE(ESR) = IP-P × RESR IP-P VRIPPLE(C) = 8 × COUT × fS where COUT is C4 in the Typical Applications Circuits. VIN × ESL L1A + ESL  V -V  V  and IP-P =  IN OUT1   OUT1  f L V    IN  S VRIPPLE(ESL) = where IP-P is the peak-to-peak inductor current (see the Inductor Selection section).
PAGE 21
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset + QGD ) IGATE where IGATE is the average DH high driver output-current capability determined by: IGATE = 2.5V R ( DH + RGATE ) LPAR = where RDH is the high-side MOSFET driver’s on-resistance (1.5Ω typ) and RGATE is the internal gate resistance of the MOSFET (≈2Ω). PQ1DR = QGS × VGS × fS × RGATE RDH (RGATE + 1) Connect a scope probe to measure VLX to GND, and observe the ringing frequency, fR .
PAGE 22
MAX8513/MAX8514 Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset To set the current limit and the current-limit foldback thresholds, first select the foldback current-limit ratio (PFB). This ratio is the foldback current limit (ILIMIT@0V) divided by the current limit when VOUT1 equals its nominal regulated voltage (ILIMIT). I PFB = LIMIT @0V ILIMIT PFB is typically set to 0.5.
PAGE 23
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset COUT = n × CEACH and RESR _ EACH RESR = n the -40dB/decade slope of the LC double pole, and the resultant compensated loop crosses over at the desired -20dB/decade slope. The error amplifier has a dominant pole at very low frequency (≈0Hz), and two separate zeros at: fZ1 = Thus the resulting fZESR is the same as that of each capacitor.
PAGE 24
MAX8513/MAX8514 Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset This gain is also set by the ratio of R3/R1 where R1 is calculated in the OUT1 Voltage Setting section. Thus: R3 = R1 × fZ2 fC × GMOD(fc) Due to the underdamped (Q > 1) nature of the output LC double pole, the error-amplifier zero frequencies must be set less than the LC double-pole frequency to provide adequate phase boost.
PAGE 25
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset MAX8513/MAX8514 Use 6.8kΩ. C12 2 2 C5 = = = 5.38nF π × R3 × fPMOD π × 6.8kΩ × 17.4kHz C11 R4 R1 EA R2 R3 × fPMOD 6.8kΩ × 17.4kHz RI = = = 583Ω fP2 × GEA(fZ1-fZ2) 423kHz × 0.479 R1 × RI 13.3kΩ × 583Ω R4 = = = 609Ω R1 - RI 13.3kΩ - 583Ω C5 R3 VOUT1 Use 4.7nF. GAIN (dB) VCOMP VREF CLOSED-LOOP GAIN Use 620Ω. C11 = EA GAIN 1 1 = = 607pF 2π × R4 × fP2 2π × 620Ω × 423kHz Use 680pF.
PAGE 26
MAX8513/MAX8514 Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset This gain between fZ1 and fZ2 is also set by the ratio of R3/R1, where R1 is selected in the OUT1 Voltage Setting section. Therefore: R3 = R1 × fPMOD fZESR × GMOD(fc) And similar to Case 1, C5 can be calculated as: C5 = fPMOD = = fZESR = 2 π × R3 × fPMOD = 1 2π L1A × C4 1 2π 6.2µH × 560µF = 2.7kHz 1 2πRESR × C4 1 = 18.95kHz 2π × 0.015Ω × 560µF Pick R2 = 8.06kΩ.
PAGE 27
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset Use 47pF. Linear-Regulator Controllers OUT2 Voltage Selection The MAX8513/MAX8514 OUT2 positive linear regulator’s output voltage is set by connecting a resistivedivider from OUT2 to FB2 to GND. The resistors in the divider are selected to set the minimum output current (IOUT2_MIN).
PAGE 28
MAX8513/MAX8514 Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset A third pole occurs due to the input capacitance of the NMOS transistor’s gate, C q (C iss from the MOSFET data sheet), and the compensation resistor (RA). If an NPN bipolar transistor is used instead, this third pole can be calculated from the base capacitance (Cq = CIBO from the NPN data sheet). To ensure stability, a zero is added to the loop from the resistor (RA) and capacitor (CA).
PAGE 29
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset When the MAX8513/MAX8514 are disabled, R26 discharges C7. transistor’s specifications, the base-emitter resistor, and the output capacitor determine the loop stability. The total DC loop gain (AV) is the product of the gains of the internal transconductance amplifier, the gain from base to collector of the pass transistor (Q4 in the Typical Applications Circuits), and the gain of the feedback divider.
PAGE 30
MAX8513/MAX8514 Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset fPOLE2 = 1 2π(CBE + CQ4IN ) × RIN || R12 If the second pole occurs well after unity-gain crossover, the linear regulator remains stable. If not, then increase the output capacitance COUT3 (C8 in the Typical Applications Circuits) so: fPOLE2 > 2 × fC _ OUT3 _ If high-ESR capacitors are used for the output capacitor (COUT3), then cancel the ESR zero with a pole at FB3_.
PAGE 31
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset C1 1µF R15 10Ω C10 2.2µF IN R10 68.1kΩ C2 10µF D1 100mA, 30V (CMOSH-3) PVL VL BST SUP2 PFI C20 30V, 5.5A DUAL N-CHANNEL 1000pF (FDS6984S) Q1 DH R11 12.4kΩ EN/SYNC C3 0.1µF R25 5.1Ω L1A LX C5 R3 6.8kΩ 4.7nF R19 200Ω Q2 FB1 C4 47µF R20 200Ω R1 13.3kΩ DL COMP1 C12 33pF C14 CSP 0.47µF PGND R7 10.7kΩ DRV2 R5 340Ω MAX8513 Q3 30V, 23A N-CHANNEL MOSFET (IRLR2703) FB2 GND C13 0.
PAGE 32
MAX8513/MAX8514 Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset VIN 9V to 16V C1 1µF R15 10Ω C10 2.2µF IN R10 68.1kΩ C2 10µF D1 100mA, 30V (CMOSH-3) PVL VL BST SUP2 PFI EN/SYNC C3 0.1µF R25 5.1Ω R19 200Ω Q2 C12 33pF C14 CSP 0.47µF PGND R7 10.7kΩ R1 13.3kΩ CSN R2 8.06kΩ FB1 FREQ IC1 DRV2 R5 1.74kΩ MAX8514 REF Q3 30V, 23A N-CHANNEL MOSFET (IRLR2703) FB2 GND C13 0.1µF C4 47µF R20 200Ω DL COMP1 C9 0.1µF COUPLED INDUCTOR L1A = 1.
PAGE 33
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset MAX8513/MAX8514 VOUT1 L1B C7 MAX8513 CBE R12 DRV3P Q4 R13 VOUT3P FB3P C8 R14 a) POSITIVE OUTPUT VOLTAGE VOUT1 SUP3N R14 VOUT1 FB3N R13 VOUT3N C8 DRV3N Q4 C BE R12 L1B MAX8514 b) NEGATIVE OUTPUT VOLTAGE C7 Figure 7. Base-Drive Noise Reduction Applications Information PC Board Layout Guidelines Careful PC board layout is critical to achieve low switching losses and clean, stable operation.
PAGE 34
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset MAX8513/MAX8514 Pin Configurations TOP VIEW PFI 1 28 SS PFI 1 28 SS PFO 2 27 CSN PFO 2 27 CSN DH 3 26 CSP DH 3 26 CSP LX 4 25 ILIM LX 4 25 ILIM BST 5 24 FB3P BST 5 DL 6 MAX8513 PVL 7 23 POR 22 IN PGND 8 21 DRV3P VL 9 20 N.C.
PAGE 35
Wide-Input, High-Frequency, Triple-Output Supplies with Voltage Monitor and Power-On Reset QSOP.EPS PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH 21-0055 E 1 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.