Maxim MAX1630CAI, MAX1630EAI, MAX1631CAI, MAX1631EAI, MAX1632CAI Schematics

KIT
EVALUATION
AVAILABLE			Supply
	Controllers for Notebook Computers

Description

buck-topology, step-down, controllers that generate -powered systems. These -output devices include on- power-good signaling with winding control, low- -compensation net-

.

through synchronous Idle Mode™ control than 80% over a 1000:1 battery life in systemdynamic response caused by the latest

five 300kHz clock cycles. ensure fast external

.

-controlled and synchroniz- -width-modulation (PWM) noise and RF interference and pen-entry applienables fixed-frequency

load conditions.

two PWM regulators, with fixed 5.0V and 3.3V secondary feedback

linear regulators. The secondary feedback input (STEER) that selects which secondary feedback sig-

nal. 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 MAX1630/MAX1631/MAX1632 contain internal output overvoltage and undervoltage protection features.

________________________Applications

Notebook and Subnotebook Computers

PDAs and Mobile Communicators

Desktop CPU Local DC-DC Converters

Pin Configurations and Selector Guide appear at end of data sheet.

Idle Mode and Dual Mode are trademarks of Maxim Integrated Products.

____________________________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 (MAX1631/MAX1634)

♦5V/50mA Linear Regulator Output

♦Precision 2.5V Reference Output

♦Programmable Power-Up Sequencing

♦Power-Good (RESET) Output

♦Output Overvoltage Protection (MAX1630/MAX1631/MAX1632)

♦Output Undervoltage Shutdown (MAX1630/MAX1631/MAX1632)

♦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

_______________Ordering Information

PART	TEMP. RANGE	PIN-PACKAGE
MAX1630CAI	0°C to +70°C	28 SSOP
MAX1630EAI	-40°C to +85°C	28 SSOP

Ordering Information continued on last page.

________________Functional Diagram

INPUT
+5V (RTC)	5V	12V	+12V
	LINEAR	LINEAR
+3.3V	3.3V	5V	+5V
	SMPS	SMPS
ON/OFF	POWER-UP	POWER-	RESET
	SEQUENCE	GOOD

________________________________________________________________ Maxim Integrated Products 1

For free samples & the latest literature: http://www.maxim-ic.com, or phone [phone]. For small orders, phone [phone] ext. 3468.

MAX1635–MAX1630

MAX1630–MAX1635

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..............................................................	-6V to +0.3V
LX5 to BST5..............................................................	-6V to +0.3V
REF, SYNC, SEQ, STEER, SKIP, TIME/ON5,
SECFB, RESET to GND ............................................	-0.3V to +6V
VDD to GND............................................................	-0.3V to +20V
RUN/ON3, SHDN to GND.............................	-0.3V to (V+ + 0.3V)
12OUT to GND ...........................................	-0.3V to (VDD + 0.3V)
DL3, DL5 to PGND........................................	-0.3V to (VL + 0.3V)
DH3 to LX3 ...............................................	-0.3V to (BST3 + 0.3V)
DH5 to LX5 ...............................................	-0.3V to (BST5 + 0.3V)

VL, REF Short to GND ................................................	Momentary
12OUT Short to GND..................................................	Continuous
REF Current...........................................................	+5mA to -1mA
VL Current.........................................................................	+50mA
12OUT Current ...............................................................	+200mA
VDD Shunt Current............................................................	+15mA
Operating Temperature Ranges
MAX163_CAI.......................................................	0°C to +70°C
MAX163_EAI....................................................	-40°C to +85°C
Storage Temperature Range .............................	-65°C to +160°C
Continuous Power Dissipation (TA = +70°C)
SSOP (derate 9.52mW/°C above +70°C) ....................	762mW
Lead Temperature (soldering, 10sec) .............................	+300°C

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.

ELECTRICAL CHARACTERISTICS

(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
MAIN SMPS CONTROLLERS
Input Voltage Range			4.2			30.0		V
3V Output Voltage in		V+ = 4.2V to 30V, CSH3–CSL3 = 0V,	2.42		2.5	2.58		V
Adjustable Mode		CSL3 tied to FB3
3V Output Voltage in Fixed Mode		V+ = 4.2V to 30V, 0mV < CSH3–CSL3 < 80mV,	3.20		3.39	3.47		V
		FB3 = 0V
5V Output Voltage in		V+ = 4.2V to 30V, CSH5–CSL5 = 0V,	2.42		2.5	2.58		V
Adjustable Mode		CSL5 tied to FB5
5V Output Voltage in Fixed Mode		V+ = 5.2V to 30V, 0mV < CSH–CSL5 < 80mV,	4.85		5.13	5.25		V
		FB5 = 0V
Output Voltage Adjust Range		Either SMPS		REF		5.5		V
Adjustable-Mode Threshold Voltage		Dual Mode comparator	0.5			1.1		V
Load Regulation		Either SMPS, 0V < CSH_–CSL_ < 80mV			-2		%
Line Regulation		Either SMPS, 5.2V < V+ < 30V			0.03			%/V
Current-Limit Threshold		CSH3–CSL3 or CSH5–CSL5		80	100	120		mV
		SKIP = VL or VDD < 13V or SECFB < 2.44V		-50	-100	-150
Idle Mode Threshold		SKIP = 0V, not tested	10		25	40		mV
Soft-Start Ramp Time		From enable to 95% full current limit with respect to			512			clks
		fOSC (Note 1)
Oscillator Frequency		SYNC = VL	270		300	330		kHz
		SYNC = 0V	170		200	230
Maximum Duty Factor		SYNC = VL		97	98			%
		SYNC = 0V (Note 2)		98	99

2 _______________________________________________________________________________________

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.)

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					200	ns
SYNC Input Frequency Range					240		350	kHz
Current-Sense Input Leakage Current		V+ = VL = 0V,				0.01	10	µA
		CSL3 = CSH3 = CSL5 = CSH5 = 5.5V
FLYBACK CONTROLLER
VDD Regulation Threshold		Falling edge (Note 3)			13		14	V
SECFB Regulation Threshold		Falling edge (MAX1631/MAX1634)			2.44		2.60	V
DL Pulse Width		VDD < 13V or SECFB < 2.44V				1		µs
VDD Shunt Threshold		Rising edge, hysteresis = 1% (Note 3)			18		20	V
VDD Shunt Sink Current		VDD = 20V (Note 3)			10			mA
VDD Leakage Current		VDD = 5V, off mode (Notes 3, 4)					30	µA
12V LINEAR REGULATOR (Note 3)
12OUT Output Voltage		13V < VDD < 18V, 0mA < ILOAD < 120mA			11.65	12.1	12.50	V
12OUT Current Limit		12OUT forced to 11V, VDD = 13V				150		mA
Quiescent VDD Current		VDD = 18V, run mode, no 12OUT load				50	100	µA
INTERNAL REGULATOR AND REFERENCE
VL Output Voltage		SHDN = V+, RUN/ON3 = TIME/ON5 = 0V,			4.7		5.1	V
		5.3V < V+ < 30V, 0mA < ILOAD < 50mA
VL Undervoltage Lockout		Falling edge, hysteresis = 1%			3.5	3.6	3.7	V
Fault Threshold
VL Switchover Threshold		Rising edge of CSL5, hysteresis = 1%			4.2	4.5	4.7	V
REF Output Voltage		No external load (Note 5)			2.45	2.5	2.55	V
REF Load Regulation		0µA < ILOAD < 50µA					12.5	mV
		0mA < ILOAD < 5mA					100.0
REF Sink Current					10			µA
REF Fault Lockout Voltage		Falling edge			1.8		2.4	V
V+ Operating Supply Current		VL switched over to CSL5, 5V SMPS on				5	50	µA
V+ Standby Supply Current		V+ = 5.5V to 30V, both SMPSs off,				30	60	µA
		includes current into SHDN
V+ Standby Supply Current		V+ = 4.2V to 5.5V, both SMPSs off,				50	200	µA
in Dropout		includes current into SHDN
V+ Shutdown Supply Current		V+ = 4V to 24V, SHDN = 0V				4	10	µA
		Both SMPSs enabled, FB3 = FB5 = 0V,	(Note 3)			2.5	4
Quiescent Power Consumption		CSL3 = CSH3 = 3.5V,	MAX1631/			1.5	4	mW
		CSL5 = CSH5 = 5.3V	MAX1634

MAX1635–MAX1630

_______________________________________________________________________________________ 3

MAX1630–MAX1635

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.)

		PARAMETER	CONDITIONS		MIN	TYP	MAX	UNITS
FAULT DETECTION (MAX1630/MAX1631/MAX1632)
	Overvoltage Trip Threshold		With respect to unloaded output voltage		4	7	10	%
	Overvoltage-Fault Propagation Delay		CSL_ driven 2% above overvoltage trip threshold			1.5		µs
	Output Undervoltage Threshold		With respect to unloaded output voltage		60	70	80	%
	Output Undervoltage Lockout Time		From each SMPS enabled, with respect to fOSC	5000		6144	7000	clks
	Thermal Shutdown Threshold		Typical hysteresis = +10°C			150		°C
	RESET
	RESET Trip Threshold		With respect to unloaded output voltage,	-7		-5.5	-4	%
			falling edge; typical hysteresis = 1%
	RESET Propagation Delay		Falling edge, CSL_ driven 2%			1.5		µs
			below RESET trip threshold
	RESET Delay Time		With respect to fOSC	27,000		32,000	37,000	clks
INPUTS AND OUTPUTS
	Feedback Input Leakage Current		FB3, FB5; SECFB = 2.6V			1	50	nA
	Logic Input Low Voltage		RUN/ON3, SKIP, TIME/ON5 (SEQ = REF),				0.6	V
			SHDN, STEER, SYNC
	Logic Input High Voltage		RUN/ON3, SKIP, TIME/ON5 (SEQ = REF),	2.4				V
			SHDN, STEER, SYNC
	Input Leakage Current		RUN/ON3, SKIP, TIME/ON5 (SEQ = REF),				±1	µA
			SHDN, STEER, SYNC, SEQ; VPIN = 0V or 3.3V
	Logic Output Low Voltage		RESET, ISINK = 4mA				0.4	V
	Logic Output High Current		RESET = 3.5V		1			mA
	TIME/ON5 Input Trip Level		SEQ = 0V or VL		2.4		2.6	V
	TIME/ON5 Source Current		TIME/ON5 = 0V, SEQ = 0V or VL		2.5	3	3.5	µA
	TIME/ON5 On-Resistance		TIME/ON5; RUN/ON3 = 0V, SEQ = 0V or VL			15	80	Ω
	Gate Driver Sink/Source Current		DL3, DH3, DL5, DH5; forced to 2V			1		A
	Gate Driver On-Resistance		High or low			1.5	7	Ω

Note 1: Each of the four digital soft-start levels is tested for functionality; the steps are typically in 20mV increments.

Note 2: High duty-factor operation supports low input-to-output differential voltages, and is achieved at a lowered operating frequency (see Overload and Dropout Operation section).

Note 3: MAX1630/MAX1632/MAX1633/MAX1635 only.

Note 4: Off mode for the 12V linear regulator occurs when the SMPS that has flyback feedback (VDD) steered to it is disabled. In situations where the main outputs are being held up by external keep-alive supplies, turning off the 12OUT regulator prevents a leakage path from the output-referred flyback winding, through the rectifier, and into VDD.

Note 5: Since the reference uses VL as its supply, the reference’s V+ line-regulation error is insignificant.

4 _______________________________________________________________________________________

Multi-Output, Low-Noise Power-Supply

Controllers for Notebook Computers

__________________________________________Typical Operating Characteristics

(Circuit of Figure 1, 3A Table 1 components, TA = +25°C, unless otherwise noted.)

EFFICIENCY vs. 5V OUTPUT CURRENT

EFFICIENCY vs. 3.3V OUTPUT CURRENT

	100				MAX1630/35-01		100				MAX1630/35-02		800
	V+ = 6V							V+ = 6V				(mA)
(%)EFFICIENCY	90					(%)EFFICIENCY	90					CURRENTOUTPUTMAXIMUM	600
			V+ = 15V
	80						80
									V+ = 15V				400
	70						70
				ON5 = 5V						ON3 = ON5 = 5V			200
	60			ON3 = 0V			60
				f = 300kHz						f = 300kHz
				MAX1631/MAX1634						MAX1631/MAX1634
	50						50						0
	0.001	0.01	0.1	1	10		0.001	0.01	0.1	1	10
		5V OUTPUT CURRENT (A)						3.3V OUTPUT CURRENT (A)

MAX1632/MAX1635

MAXIMUM 15V VDD OUTPUT CURRENT vs. SUPPLY VOLTAGE

				-03
	VDD > 13V			1630/35
	5V REGULATING
				MAX
	5V LOAD = 0A
			5V LOAD = 3A
0	5	10	15	20
	SUPPLY VOLTAGE (V)

					MAX1630/MAX1633													PWM MODE INPUT CURRENT															IDLE MODE INPUT CURRENT
					MAXIMUM 15V VDD OUTPUT
				CURRENT vs. SUPPLY VOLTAGE															vs. INPUT VOLTAGE															vs. INPUT VOLTAGE
	500														1630/35MAX -04	30													MAX1630/35-05		10													MAX1630/35-06
(mA)	400																						NO	LOAD														ON3 = ON5				= 5V
																																						NO LOAD
			VDD		> 13V																		ON3		= ON5		= 5V
			3.3V REGULATING													25							SKIP = VL															SKIP = 0V
CURRENTOUTPUTMAXIMUM	100														(mA)CURRENTINPUT															(mA)CURRENTINPUT
																5
				3.3V LOAD = 0A
	300															20															1
	200															15
																10															0.1
	0								3.3V LOAD = 3A							0															0.01
	0				5			10			15			20		0		5	10		15		20			25		30			0		5	10		15		20			25		30
						SUPPLY VOLTAGE (V)													INPUT VOLTAGE (V)															INPUT VOLTAGE (V)

INPUT CURRENT (μA)

STANDBY INPUT CURRENT vs. INPUT VOLTAGE

10,000

ON3 = ON5 = 0V

NO LOAD

1000

100

10

1

0

5

10

15

20

25

INPUT VOLTAGE (V)

MAX1630/35-07 INPUT CURRENT (μA)

30

			SHUTDOWN INPUT CURRENT
				vs. INPUT VOLTAGE
10													-08
													MAX1630/35
			SHDN = 0V
8
6
4
2
0
0		5		10		15		20		25		30

INPUT VOLTAGE (V)

MINIMUM VIN TO VOUT DIFFERENTIAL

vs. 5V OUTPUT CURRENT

	1000																																	-09
(mV)																																		MAX1630/35
DIFFERENTIAL	100
OUT
TO V	10
IN
V
MIN				5V, 3A CIRCUIT
				VOUT > 4.8V
	1			f = 300kHz
	0.001			0.01										0.1							1								10

5V OUTPUT CURRENT (A)

MAX1635–MAX1630

_______________________________________________________________________________________ 5

MAX1630–MAX1635

Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers

____________________________________Typical Operating Characteristics (continued)

(Circuit of Figure 1, 3A Table 1 components, TA = +25°C, unless otherwise noted.)

SWITCHING FREQUENCY	VL REGULATOR OUTPUT VOLTAGE
vs. LOAD CURRENT	vs. OUTPUT CURRENT

	1000				MAX1630/35-10		5.00						MAX 1630/35-11
(kHz)	100					(V)	4.98
FREQUENCYSWITCHING	1		+3.3V, VIN = 6V			OUTPUTVLVOLTAGE
			+5V, VIN = 15V
							4.96
	10	+3.3V, VIN = 15V
							4.94
							4.92	VIN = 15V
			+5V, VIN = 6V
								ON3 = ON5 = 0V
	0.1						4.90					50	60
	0.1	1	10	100	1000		0	10	20	30	40
			LOAD CURRENT (mA)						OUTPUT CURRENT (mA)

REF OUTPUT VOLTAGE

START-UP WAVEFORMS

vs. OUTPUT CURRENT

2.510

MAX 1630/35-12

RUN

MAX1630/35-13

2.505

(V)

5V/div

2V/div

VOLTAGE

2.500

3.3V OUTPUT

OUTPUT

2.495

5V/div

TIME

REF

2.490

5V OUTPUT

2.485

VIN = 15V

5V/div

ON3 = ON5 = 0V

2.480

2ms/div

0

1

2

3

4

5

6

OUTPUT CURRENT (mA)

SEQ = VL, 0.015μF CAPACITOR ON-TIME

__________________________________________________________________________Pin Description

	PIN	NAME	FUNCTION
	1	CSH3	Current-Sense Input for the 3.3V SMPS. Current-limit level is 100mV referred to CSL3.
	2	CSL3	Current-Sense Input. Also serves as the feedback input in fixed-output mode.
			Feedback Input for the 3.3V SMPS; regulates at FB3 = REF (approx. 2.5V) in adjustable mode. FB3 is a
	3	FB3	Dual Mode input that also selects the 3.3V fixed output voltage setting when tied to GND. Connect FB3
			to a resistor divider for adjustable-output mode.
		12OUT	12V/120mA Linear Regulator Output. Input supply comes from VDD. Bypass 12OUT to GND with
		(MAX1630/
			1µF minimum.
		32/33/35)
	4
		STEER	Logic-Control Input for secondary feedback. Selects the PWM that uses a transformer and secondary
			feedback signal (SECFB):
		(MAX1631/
			STEER = GND: 3.3V SMPS uses transformer
		MAX1634)
			STEER = VL: 5V SMPS uses transformer

6 _______________________________________________________________________________________

Multi-Output, Low-Noise Power-Supply

Controllers for Notebook Computers

_________________________________________________Pin Description (continued)

	PIN	NAME	FUNCTION
		VDD	Supply Voltage Input for the 12OUT Linear Regulator. Also connects to an internal resistor divider for
		(MAX1630/
			secondary winding feedback, and to an 18V overvoltage shunt regulator clamp.
		32/33/35)
	5
		SECFB	Secondary Winding Feedback Input. Normally connected to a resistor divider from an auxiliary output.
		(MAX1631/	SECFB regulates at VSECFB = 2.5V (see Secondary Feedback Regulation Loop section). Tie to VL if not
		MAX1634)	used.
	6	SYNC	Oscillator Synchronization and Frequency Select. Tie to VL for 300kHz operation; tie to GND for 200kHz
			operation. Can be driven at 240kHz to 350kHz for external synchronization.
	7	TIME/ON5	Dual-Purpose Timing Capacitor Pin and ON/OFF Control Input. See Power-Up Sequencing and
			ON/OFF Controls section.
	8	GND	Low-Noise Analog Ground and Feedback Reference Point
	9	REF	2.5V Reference Voltage Output. Bypass to GND with 1µF minimum.
	10	SKIP	Logic-Control Input that disables Idle Mode when high. Connect to GND for normal use.
	11	RESET	Active-Low Timed Reset Output. RESET swings GND to VL. Goes high after a fixed 32,000 clock-cycle
			delay following power-up.
			Feedback Input for the 5V SMPS; regulates at FB5 = REF (approx. 2.5V) in adjustable mode. FB5 is a
	12	FB5	Dual Mode input that also selects the 5V fixed output voltage setting when tied to GND. Connect FB5 to
			a resistor divider for adjustable-output mode.
	13	CSL5	Current-Sense Input for the 5V SMPS. Also serves as the feedback input in fixed-output mode, and as
			the bootstrap supply input when the voltage on CSL5/VL is > 4.5V.
	14	CSH5	Current-Sense Input for the 5V SMPS. Current-limit level is 100mV referred to CSL5.
			Pin-Strap Input that selects the SMPS power-up sequence:
	15	SEQ	SEQ = GND: 5V before 3.3V, RESET output determined by both outputs
			SEQ = REF: Separate ON3/ON5 controls, RESET output determined by 3.3V output
			SEQ = VL: 3.3V before 5V, RESET output determined by both outputs
	16	DH5	Gate-Drive Output for the 5V, high-side N-channel switch. DH5 is a floating driver output that swings
			from LX5 to BST5, riding on the LX5 switching node voltage.
	17	LX5	Switching Node (inductor) Connection. Can swing 2V below ground without hazard.
	18	BST5	Boost capacitor connection for high-side gate drive (0.1µF)
	19	DL5	Gate-Drive Output for the low-side synchronous-rectifier MOSFET. Swings 0V to VL.
	20	PGND	Power Ground
			5V Internal Linear-Regulator Output. VL is also the supply voltage rail for the chip. After the 5V SMPS
	21	VL	output has reached +4.5V (typical), VL automatically switches to the output voltage via CSL5 for boot-
			strapping. Bypass to GND with 4.7µF. VL supplies up to 25mA for external loads.
	22	V+	Battery Voltage Input, +4.2V to +30V. Bypass V+ to PGND close to the IC with a 0.22µF capacitor.
			Connects to a linear regulator that powers VL.
	23	SHDN	Shutdown Control Input, active low. Logic threshold is set at approximately 1V. For automatic start-up,
			connect SHDN to V+ through a 220kΩ resistor and bypass SHDN to GND with a 0.01µF capacitor.
	24	DL3	Gate-Drive Output for the low-side synchronous-rectifier MOSFET. Swings 0V to VL.
	25	BST3	Boost Capacitor Connection for high-side gate drive (0.1µF)
	26	LX3	Switching Node (inductor) Connection. Can swing 2V below ground without hazard.
	27	DH3	Gate-Drive Output for the 3.3V, high-side N-channel switch. DH3 is a floating driver output that swings
			from LX3 to BST3, riding on the LX3 switching node voltage.
	28	RUN/ON3	ON/OFF Control Input. See Power-Up Sequencing and ON/OFF Controls section.

MAX1635–MAX1630

_______________________________________________________________________________________ 7

Multi-Output, Low-Noise Power-Supply Controllers for Notebook Computers

MAX1630–MAX1635			INPUT		ON/OFF
							+5V ALWAYS ON
			C3				4.7μF
					10Ω
							0.1μF
					0.1μF
					V+ SHDN SECFB VL
					4.7μF	SYNC
					BST5	BST3
				Q1	DH5	DH3	Q3
				0.1μF	0.1μF	0.1μF	0.1μF
	+5V OUTPUT		R1	L1	LX5	LX3	L2	R2	+3.3V OUTPUT
	C1	*		Q2	DL5	MAX1631			*	C2
						MAX1634 DL3	Q4
					PGND
					CSH5	CSH3
					CSL5	CSL3
						FB3
					FB5
						RESET	RESET OUTPUT
			5V ON/OFF		TIME/ON5
			3.3V ON/OFF			SKIP
					RUN/ON3
						STEER
					GND
					REF	SEQ
							+2.5V ALWAYS ON
						1μF
						*1A SCHOTTKY DIODE REQUIRED
						FOR THE MAX1631 (SEE OUTPUT
						OVERVOLTAGE PROTECTION SECTION).

Figure 1. Standard 3.3V/5V Application Circuit (MAX1631/MAX1634)

_______Standard Application Circuit

The basic MAX1631/MAX1634 dual-output 3.3V/5V buck converter (Figure 1) is easily adapted to meet a wide range of applications with inputs up to 28V by substituting components from Table 1. These circuits represent a good set of tradeoffs between cost, size, and efficiency, while staying within the worst-case specification limits for stress-related parameters, such as capacitor ripple current. Don’t change the frequency

of these circuits without first recalculating component values (particularly inductance value at maximum battery voltage). Adding a Schottky rectifier across each synchronous rectifier improves the efficiency of these circuits by approximately 1%, but this rectifier is otherwise not needed because the MOSFETs required for these circuits typically incorporate a high-speed silicon diode from drain to source. Use a Schottky rectifier rated at a DC current equal to at least one-third of the load current.

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Multi-Output, Low-Noise Power-Supply

Controllers for Notebook Computers

Table 1. Component Selection for Standard 3.3V/5V Application

	COMPONENT			LOAD CURRENT
			2A	3A	4A
	Input Range		4.75V to 18V	4.75V to 28V	4.75V to 24V
	Application		PDA	Notebook	Workstation
	Frequency		300kHz	300kHz	200kHz
			1/2 IR IRF7301;	IR IRF7403 or IRF7401 (18V	IR IRF7413 or
	Q1, Q3 High-Side		1/2 Siliconix Si9925DQ; or	max); Siliconix Si4412DY; or	Siliconix Si4410DY
	MOSFETs		1/2 Motorola MMDF3N03HD or	Motorola MMSF5N03HD or
			MMDF4N01HD (10V max)	MMSF5N02HD (18V max)
			1/2 IR IRF7301;	IR IRF7403 or IRF7401 (18V	IR IRF7413 or
	Q2, Q4 Low-Side		1/2 Siliconix Si9925DQ; or	max); Siliconix Si4412DY; or	Siliconix Si4410DY
	MOSFETs		1/2 Motorola MMDF3N03HD or	Motorola MMSF5N03HD or
			MMDF4N01HD (10V max)	MMSF5N02HD (18V max)
			10µF, 30V Sanyo OS-CON;	2 x 10µF, 30V Sanyo OS-CON;	3 x 10µF, 30V Sanyo OS-CON;
	C3 Input Capacitor		22µF, 35V AVX TPS; or	2 x 22µF, 35V AVX TPS; or	4 x 22µF, 35V AVX TPS; or
			Sprague 594D	Sprague 594D	Sprague 595D
	C1, C2 Output Capacitors		220µF, 10V AVX TPS or	2 x 220µF, 10V AVX TPS or	4 x 220µF, 10V AVX TPS or
			Sprague 595D	Sprague 595D	Sprague 595D
	R1, R2 Resistors		0.033Ω IRC LR2010-01-R033 or	0.02Ω IRC LR2010-01-R020 or	0.012Ω Dale WSL2512-R012-F
			Dale WSL2010-R033-F	Dale WSL2010-R020-F
			15µH, 2.4A Ferrite	10µH, 4A Ferrite	4.7µH, 5.5A Ferrite
	L1, L2 Inductors		Coilcraft DO3316P-153 or	Coilcraft DO3316P-103 or	Coilcraft DO3316-472 or
			Sumida CDRH125-150	Sumida CDRH125-100	5.2µH, 6.5A Ferrite Sumida
					CDRH127-5R2MC

Table 2. Component Suppliers

	COMPANY	FACTORY FAX	USA PHONE
		(COUNTRY CODE)
	AVX	(1) 803-626-3123	[phone]
	Central	(1) 516-435-1824	[phone]
	Semiconductor
	Coilcraft	(1) 847-639-1469	[phone]
	Coiltronics	(1) 561-241-9339	[phone]
	Dale	(1) 605-665-1627	[phone]
	International	(1) 310-322-3332	[phone]
	Rectifier (IR)
	IRC	(1) 512-992-3377	[phone]
	Matsuo	(1) 714-960-6492	[phone]

*Distributor

COMPANY			FACTORY FAX	USA PHONE
			(COUNTRY CODE)
Motorola			(1) 602-994-6430	(602)	303-5454
Murata-Erie			(1) 814-238-0490	(814)	237-1431
NIEC		(81) 3-3494-7414		(805)	867-2555*
Sanyo			(81) 7-2070-1174	(619)	661-6835
Siliconix			(1) 408-970-3950	(408)	988-8000
Sprague			(1) 603-224-1430	(603)	224-1961
Sumida			(81) 3-3607-5144	(847)	956-0666
TDK			(1) 847-390-4428	(847)	390-4373
Transpower			(1) 702-831-3521	(702)	831-0140
Technologies

MAX1635–MAX1630

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