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________________General Description

The MAX1630A–MAX1635A are buck-topology, step-

down, switch-mode, power-supply controllers that gener-

ate logic-supply voltages in battery-powered systems.

These high-performance, dual-/triple-output devices

include on-board power-up sequencing, power-good

signaling with delay, digital soft-start, secondary winding

control, low-dropout circuitry, internal frequency-com-

pensation networks, and automatic bootstrapping.

Up to 96% efficiency is achieved through synchronous

rectification and Maxim’s proprietary Idle Mode™ control

scheme. Efficiency is greater than 80% over a 1000:1

load-current range, which extends battery life in system-

suspend or standby mode. Excellent dynamic response

corrects output load transients caused by the latest

dynamic-clock CPUs within five 300kHz clock cycles.

Strong 1A on-board gate drivers ensure fast external

n-channel MOSFET switching.

These devices feature a logic-controlled and synchroniz-

able, fixed-frequency, pulse-width-modulation (PWM)

operating mode. This reduces noise and RF interference

in sensitive mobile communications and pen-entry appli-

cations. Asserting the SKIP pin enables fixed-frequency

mode for lowest noise under all load conditions.

The MAX1630A–MAX1635A include two PWM regulators,

adjustable from 2.5V to 5.5V with fixed 5.0V and 3.3V

modes. All these devices include secondary feedback

regulation, and the MAX1630A/MAX1632A/MAX1633A/

MAX1635A each contain 12V/120mA linear regulators.

The MAX1631A/MAX1634A include a secondary feed-

back input (SECFB), plus a control pin (STEER) that

selects which PWM (3.3V or 5V) receives the secondary

feedback signal. SECFB provides a method for adjusting

the secondary winding voltage regulation point with an

external resistor-divider, and is intended to aid in creating

auxiliary voltages other than fixed 12V.

The MAX1630A/MAX1631A/MAX1632A contain internal

output overvoltage and undervoltage protection features.

The MAX1630A family has improved RF immunity over

the MAX1630 family.

________________________Applications

Notebook and Subnotebook Computers

PDAs and Mobile Communicators

Desktop CPU Local DC-DC Converters

____________________________Features

♦ 96% Efficiency

♦ +4.2V to +30V Input Range

♦ 2.5V to 5.5V Dual Adjustable Outputs

♦ Selectable 3.3V and 5V Fixed or Adjustable

Outputs (Dual Mode™)

♦ 12V Linear Regulator

♦ Adjustable Secondary Feedback

(MAX1631A/MAX1634A)

♦ 5V/50mA Linear Regulator Output

♦ Precision 2.5V Reference Output

♦ Programmable Power-Up Sequencing

♦ Power-Good (RESET) Output

♦ Output Overvoltage Protection

(MAX1630A/MAX1631A/MAX1632A)

♦ Output Undervoltage Shutdown

(MAX1630A/MAX1631A/MAX1632A)

♦ 200kHz/300kHz Low-Noise, Fixed-Frequency

Operation

♦ Low-Dropout, 99% Duty-Factor Operation

♦ 2.5mW Typical Quiescent Power (+12V Input,

Both SMPSs On)

♦ 4µA Typical Shutdown Current

♦ 28-Pin SSOP Package

MAX1630A–MAX1635A

Multi-Output, Low-Noise Power-Supply

Controllers for Notebook Computers

________________________________________________________________ Maxim Integrated Products 1

LINEAR

12V

LINEAR

POWER-UP

SEQUENCE

POWER-

GOOD

3.3V

SMPS

RESETON/OFF

+5V (RTC)

+3.3V

INPUT

+5V

+12V

________________Functional Diagram

19-3518; Rev 1; 8/05

PART

MAX1630AEAI

-40°C to +85°C

TEMP RANGE PIN-PACKAGE

28 SSOP

EVALUATION KIT

AVAILABLE

_______________Ordering Information

+Denotes lead-free package.

Ordering Information continued at end of data sheet.

Pin Configurations and Selector Guide appear at end of data

sheet.

Idle Mode and Dual Mode are trademarks of Maxim Integrated

Products, Inc.

Summary of content (29 pages)

PAGE 1
9-3518; Rev 1; 8/05 KIT ATION EVALU E L B A IL AVA Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers ____________________________Features The MAX1630A–MAX1635A are buck-topology, stepdown, switch-mode, power-supply controllers that generate logic-supply voltages in battery-powered systems.
PAGE 2
MAX1630A–MAX1635A Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers ABSOLUTE MAXIMUM RATINGS V+ to GND ..............................................................-0.3V to +36V PGND to GND.....................................................................±0.3V VL to GND ................................................................-0.3V to +6V BST3, BST5 to GND ...............................................-0.3V to +36V LX3 to BST3...............................................
PAGE 3
Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers (V+ = 15V, both PWMs on, SYNC = VL, VL load = 0mA, REF load = 0mA, SKIP = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER CONDITIONS MIN TYP MAX UNITS SYNC Input High Pulse Width Not tested 200 ns SYNC Input Low Pulse Width Not tested 200 ns SYNC Rise/Fall Time Not tested SYNC Input Frequency Range Current-Sense Input Leakage Current 200 ns 350 kHz 10 µA 13 14 V 2.
PAGE 4
MAX1630A–MAX1635A Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers ELECTRICAL CHARACTERISTICS (continued) (V+ = 15V, both PWMs on, SYNC = VL, VL load = 0mA, REF load = 0mA, SKIP = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.
PAGE 5
Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers 80 70 ON5 = 5V ON3 = 0V f = 300kHz MAX1631A/MAX1634A 60 70 ON3 = ON5 = 5V f = 300kHz MAX1631A/MAX1634A 0.01 0.1 1 10 VDD > 13V 5V REGULATING 600 5V LOAD = 0A 400 5V LOAD = 3A 200 0 50 0.001 0.001 0.01 0.1 1 5 0 10 10 15 20 5V OUTPUT CURRENT (A) 3.3V OUTPUT CURRENT (A) SUPPLY VOLTAGE (V) MAX1630A/MAX1633A MAXIMUM 15V VDD OUTPUT CURRENT vs. SUPPLY VOLTAGE PWM MODE INPUT CURRENT vs.
PAGE 6
____________________________________Typical Operating Characteristics (continued) (Circuit of Figure 1, 3A Table 1 components, TA = +25°C, unless otherwise noted.) SWITCHING FREQUENCY vs. LOAD CURRENT VL REGULATOR OUTPUT VOLTAGE vs. OUTPUT CURRENT +5V, VIN = 15V 10 +3.3V, VIN = 15V +3.3V, VIN = 6V 1 MAX1630A/35A toc11 100 5.00 VL OUTPUT VOLTAGE (V) MAX1630A/35A toc010 SWITCHING FREQUENCY (kHz) 1000 4.98 4.96 4.94 4.92 +5V, VIN = 6V VIN = 15V ON3 = ON5 = 0V 0.1 4.
PAGE 7
Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers PIN NAME FUNCTION VDD (MAX1630A/ 32A/33A/35A) Supply Voltage Input for the 12OUT Linear Regulator. Also connects to an internal resistor-divider for secondary winding feedback, and to an 18V overvoltage shunt regulator clamp. SECFB (MAX1631A/ MAX1634A) Secondary Winding Feedback Input. Normally connected to a resistor-divider from an auxiliary output. SECFB regulates at VSECFB = 2.
PAGE 8
MAX1630A–MAX1635A Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers ON/OFF INPUT +5V ALWAYS ON C3 10Ω 4.7μF 0.1μF 0.1μF V+ SHDN SECFB VL 4.7μF Q1 0.1μF R1 +5V OUTPUT C1 BST3 DH5 L1 Q3 DH3 0.1μF 0.1μF LX5 Q2 * SYNC BST5 0.1μF L2 LX3 DL5 MAX1631A MAX1634A DL3 R2 +3.3V OUTPUT * C2 Q4 PGND CSH5 CSH3 CSL5 CSL3 FB3 FB5 RESET 5V ON/OFF TIME/ON5 3.3V ON/OFF RUN/ON3 RESET OUTPUT SKIP STEER GND SEQ REF +2.
PAGE 9
Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers LOAD CURRENT COMPONENT 2A 3A 4A Input Range 4.75V to 18V 4.75V to 28V 4.
PAGE 10
MAX1630AA–MAX1635A Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers _______________Detailed Description The MAX1630A is a dual, BiCMOS, switch-mode powersupply controller designed primarily for buck-topology regulators in battery-powered applications where high efficiency and low quiescent supply current are critical. Lightload efficiency is enhanced by automatic Idle Mode operation, a variable-frequency pulse-skipping mode that reduces transition and gate-charge losses.
PAGE 11
Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers MAX1630A–MAX1635A INPUT V+ SHDN SYNC CSL5 + MAX1632A 4.5V ON/OFF +5V ALWAYS ON 12V LINEAR REG 5V LINEAR REG VL REF VDD + - 13V DH3 BST5 RAW +15V DH5 LX3 +3.3V +12V IN SECFB 2.5V REF BST3 12OUT VL DL3 3.3V PWM LOGIC 5V PWM LOGIC 200kHz TO 300kHz OSC LX5 +5V VL DL5 PGND OV/UV FAULT + REF - REF LPF 60kHz + LPF 60kHz 1.75V 2.68V CSH5 CSL5 - CSH3 CSL3 2.
PAGE 12
MAX1630A–MAX1635A Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers CSH_ 1X CSL_ REF FROM FEEDBACK DIVIDER MAIN PWM COMPARATOR BST_ R LEVEL SHIFT Q S DH_ LX_ SLOPE COMP OSC 30mV SKIP CURRENT LIMIT DAC SHOOTTHROUGH CONTROL CK COUNTER SHDN SOFT-START SYNCHRONOUS RECTIFIER CONTROL R -100mV S VL Q LEVEL SHIFT DL_ PGND REF 1μs SINGLE-SHOT SECFB Figure 3.
PAGE 13
Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers (ESR) (see the Design Procedure section). A 60kHz pole-zero cancellation filter provides additional rolloff above the unity-gain crossover. This internal 60kHz lowpass compensation filter cancels the zero due to filter capacitor ESR. The 60kHz filter is included in the loop in both fixed-output and adjustable-output modes.
PAGE 14
MAX1630A–MAX1635A Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers Internal VL and REF Supplies An internal regulator produces the +5V supply (VL) that powers the PWM controller, logic, reference, and other blocks within the IC. This 5V low-dropout linear regulator supplies up to 25mA for external loads, with a reserve of 25mA for supplying gate-drive power. Bypass VL to GND with 4.7µF. Important: Ensure that VL does not exceed 6V. Measure VL with the main output fully loaded.
PAGE 15
Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers Power-Up Sequencing and ON/OFF Controls Startup is controlled by RUN/ON3 and TIME/ON5 in conjunction with SEQ. With SEQ tied to REF, the two control inputs act as separate ON/OFF controls for each supply. With SEQ tied to VL or GND, RUN/ON3 becomes the master ON/OFF control input and TIME/ON5 becomes a timing pin, with the delay between the two supplies determined by an external capacitor. The delay is approximately 800µs/nF. The +3.
PAGE 16
MAX1630A–MAX1635A Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers Discharging the output capacitor through the main inductor causes the output to momentarily go below GND. Clamp this negative pulse with a back-biased 1A Schottky diode across the output capacitor (Figure 1). To ensure overvoltage protection on initial power-up, connect signal diodes from both output voltages to VL (cathodes to VL) to eliminate the VL power-up delay.
PAGE 17
Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers R2 SECFB 1-SHOT TRIG 2.5V REF Devices with a 12OUT linear regulator have a VDD pin that regulates at a fixed 13.5V, set by an internal resistor-divider. The MAX1631A/MAX1634A have an adjustable secondary output voltage set by an externalresistor-divider on SECFB (Figure 5). Ordinarily, the secondary regulation point is set 5% to 10% below the voltage normally produced by the flyback effect.
PAGE 18
MAX1630A–MAX1635A Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers rate output of more than 120mA is needed, an external pass transistor can be added. Figure 6’s circuit delivers more than 200mA. Total output current is constrained by the V+ input voltage and the transformer primary load (see Maximum 15V V DD Output Current vs. Supply Voltage graphs in the Typical Operating Characteristics).
PAGE 19
Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers Output Filter Capacitor Value The output filter capacitor values are generally determined by the ESR and voltage rating requirements, rather than actual capacitance requirements for loop stability. In other words, the low-ESR electrolytic capacitor that meets the ESR requirement usually has more output capacitance than is required for AC stability.
PAGE 20
MAX1630A–MAX1635A Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers full equation for ripple in continuous-conduction mode is V NOISE (P-P) = I RIPPLE x [R ESR + 1/(2 x π x f x COUT)]. In Idle Mode, the inductor current becomes discontinuous, with high peaks and widely spaced pulses, so the noise can actually be higher at light load (compared to full load). In Idle Mode, calculate the output ripple as follows: VNOISE(P-P) = 0.02 x RESR + RSENSE [ ] 0.
PAGE 21
Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers 20ns = DH driver inherent rise/fall time Under output short circuit, the MAX1633A/MAX1634A/ MAX1635As’ synchronous rectifier MOSFET suffers extra stress because its duty factor can increase to greater than 0.9. It may need to be oversized to tolerate a continuous DC short circuit. During short circuit, the MAX1630A/MAX1631A/MAX1632As’ output undervoltage shutdown protects the synchronous rectifier under output short-circuit conditions.
PAGE 22
MAX1630A–MAX1635A Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers Table 5. Low-Voltage Troubleshooting Chart SYMPTOM CONDITION ROOT CAUSE SOLUTION Sag or droop in VOUT under step-load change Low VIN-VOUT differential, <1.5V Limited inductor-current slew rate per cycle. Increase bulk output capacitance per formula (see the Low-Voltage Operation section). Reduce inductor value.
PAGE 23
Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers This power is dissipated in the MOSFET body diode if no external Schottky diode is used: P(cap) = input capacitor ESR loss = (IRMS )2 x RESR where IRMS is the input ripple current as calculated in the Design Procedure and Input Capacitor Value sections. Light-Load Efficiency Considerations Under light loads, the PWM operates in discontinuous mode, where the inductor current discharges to zero at some point during the switching cycle.
PAGE 24
MAX1630A–MAX1635A Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers _______________________________________________________________________________Application Circuits * TO +3.3V OUTPUT * TO +5V OUTPUT INPUT +5.2V TO +24V C3 C4 10Ω 4.7μF 0.1μF ON/OFF 23 22 6 0.1μF 21 +5V ALWAYS ON 4.7μF SHDN V+ SYNC VL 5 25 2.7μF Q1 27 VDD 12OUT BST3 BST5 DH5 DH3 4 +12V AT 120mA 2.2μF 18 16 Q3 0.1μF C1 +3.3V OUTPUT (3A) L2 * R1 T1 1:4 0.1μF 26 0.
PAGE 25
Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers * TO +3.3V OUTPUT * TO +5V OUTPUT INPUT +6.5V TO +28V C3 C4 10Ω 4.7μF 0.1μF +5V ALWAYS ON ON/OFF 23 22 6 0.1μF 21 4.7μF SHDN V+ SYNC VL 12OUT VDD D1 25 Q1 27 L1 +3.3V OUTPUT (3A) C1 * R1 BST5 BST3 +12V AT 120mA 4 2.2μF 5 D2 D5 18 2.2μF 16 Q3 DH3 DH5 LX3 LX5 17 DL5 19 PGND 20 R2 0.1μF 26 0.
PAGE 26
MAX1630A–MAX1635A Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers _____________________________________________________________Application Circuits (continued) ON/OFF * * INPUT +6V TO +24V 5V ALWAYS ON C3 10Ω 22 0.1μF 23 5 21 4.7μF V+ SHDN SECFB VL 4.7μF 18 2.5V OUTPUT 0.1μF L1 R1 BST5 16 Q1 BST3 DH5 DH3 Q2 C1 1N5819 0.1μF 27 0.1μF Q3 0.
PAGE 27
Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers TOP VIEW CSH3 1 28 RUN/ON3 CSH3 1 28 RUN/ON3 CSL3 2 27 DH3 CSL3 2 27 DH3 FB3 3 26 LX3 FB3 3 26 LX3 12OUT 4 VDD 5 MAX1630A MAX1632A MAX1633A MAX1635A SYNC 6 TIME/ON5 7 25 BST3 STEER 4 24 DL3 SECFB 5 SYNC 6 23 SHDN 25 BST3 MAX1631A MAX1634A 24 DL3 23 SHDN 22 V+ TIME/ON5 7 22 V+ GND 8 21 VL GND 8 21 VL REF 9 20 PGND REF 9 20 PGND SKIP 10 19 DL5 SKIP 10 19 DL5 RESET 11 18 BST5 RESET 11 18 BST5 FB5
PAGE 28
MAX1630A–MAX1635A Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers __Ordering Information (continued) PART MAX1630AEAI+ TEMP RANGE -40°C to +85°C PIN-PACKAGE 28 SSOP MAX1631AEAI -40°C to +85°C 28 SSOP MAX1631AEAI+ -40°C to +85°C 28 SSOP MAX1632AEAI -40°C to +85°C 28 SSOP MAX1632AEAI+ -40°C to +85°C 28 SSOP MAX1633AEAI -40°C to +85°C 28 SSOP MAX1633AEAI+ -40°C to +85°C 28 SSOP MAX1634AEAI -40°C to +85°C 28 SSOP MAX1634AEAI+ -40°C to +85°C 28 SSOP MAX1635AEAI
PAGE 29
Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.) 2 SSOP.EPS MAX1630A–MAX1635A Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers 1 INCHES E H MILLIMETERS DIM MIN MAX MIN MAX A 0.068 0.078 1.73 1.99 A1 0.002 0.008 0.05 0.21 B 0.010 0.015 0.25 0.38 C 0.20 0.09 0.004 0.008 SEE VARIATIONS D E e 0.205 0.212 0.