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19-0459; Rev 1; 1/99
Low-Profile, 5V/12V or Adjustable, Step-Up DC-DC Converters for Flash Memory/PCMCIA Cards
General Description
The MAX606/MAX607 are the smallest CMOS, step-up DC-DC converters available for flash memory and PC (PCMCIA) cards. They switch at up to 1MHz, permitting the entire circuit to fit in 0.25in 2 , yet remain under 1.35mm high to fit Type 1, 2, and 3 card standards. These devices operate from a 3V to 5.5V input and provide a 4% accurate output that is preset to 5V or 12V, or adjustable from VIN to 12.5V. They can provide up to 180mA of output current at 5V. The MAX606 switches at up to 1MHz and fits Type 1 (thinnest standard) flash memory and PCMCIA cards. It uses a thin, 1.19mm high, 5H inductor and small, 0.68F output capacitors. The entire circuit fits in 0.25in2 and is less than 1.35mm high. The MAX607 switches at up to 500kHz, fitting Type 2 and 3 cards, as well as hand-held devices where height requirements are not as critical. It uses less board area than the MAX606, fitting in 0.16in 2, but requires 2.5mm of height. It also has a lower no-load supply current than the MAX606. Both devices use a unique control scheme that optimizes efficiency over all input and output voltages. Other features include 1A logic-controlled shutdown and usercontrolled soft-start to minimize inrush currents. The MAX606/MAX607 come in 8-pin MAX and SO packages. The MAX package uses half the board area of a standard 8-pin SO and has a maximum height of just 1.11mm.
UAL IT MAN TION K SHEET VALUA E TA WS DA FOLLO
____________________________Features
o Lowest-Height Circuit (1.35mm max) o 4% Regulated Output (5V, 12V, or Adjustable) o Up to 180mA Load Current o 1MHz Switching Frequency (MAX606) o 1A Logic-Controlled Shutdown o 3V to 5.5V Input Voltage Range o Compact 8-Pin MAX Package
MAX606/MAX607
Ordering Information
PART MAX606ESA MAX606EUA MAX607ESA MAX607EUA TEMP. RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 8 SO 8 MAX 8 SO 8 MAX
________________________Applications
PCMCIA Cards Memory Cards Single PCMCIA Slot Programming Digital Cameras Flash Memory Programming Hand-Held Equipment
INPUT +4.5V TO +5.5V
Typical Operating Circuit
Pin Configuration
TOP VIEW
PGND FB SHDN IN 1 2 3 4 8 LX OUT SS GND
0.68F
0.68F
0.1F
5H IN OUTPUT 12V @ 90mA 0.68F x2
ON/OFF
SHDN
LX
FB MAX606 OUT GND
MAX606 MAX607
SO/MAX
7 6 5
PGND
________________________________________________________________ Maxim Integrated Products
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Low-Profile, 5V/12V or Adjustable, Step-Up DC-DC Converters for Flash Memory/PCMCIA Cards MAX606/MAX607
ABSOLUTE MAXIMUM RATINGS
IN to GND .................................................................-0.3V to +6V LX, OUT to GND .....................................................-0.3V to +15V PGND to GND.....................................................................0.3V FB to GND ..................................................-0.3V to (VCC + 0.3V) SS, SHDN to GND ....................................................-0.3V to +6V Continuous Power Dissipation (TA = +70C) MAX (derate 4.10mW/C above +70C) ....................330mW SO (derate 5.88mW/C above +70C) .........................471mW Operating Temperature Range ...........................-40C to +85C Storage Temperature .......................................................+160C Lead Temperature (soldering, 10sec) .............................+300C
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
(VIN = 3.3V, GND = PGND = FB = 0V, SHDN = IN, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Supply Voltage Undervoltage Lockout Threshold Output Voltage (Note 1) FB Regulation Setpoint Adjustable Output Voltage Range Line Regulation Switch On-Resistance Switch Off-Leakage Switch Current Limit SS Resistance Quiescent Supply Current Shutdown Quiescent Current OUT Input Current Switch On-Time Constant (K) Switch Off-Time Ratio SHDN Input Low Voltage SHDN Input High Voltage SHDN Input Current FB Input Low Voltage FB Input High Voltage FB Input Current V SHDN = VIN, VSS = 150mV V SHDN = VSS = 0 VOUT = 13V V SHDN = 0, OUT = IN VOUT = 13V 3V < VIN < 5.5V (tON = K / VIN) MAX606 MAX607 1.9 3.8 0.3 3.0 6.0 MAX606 MAX607 250 150 0.01 VLX = 12V 0.7 30 45 3V < VIN < 5V, FB = IN, ILOAD = 0 to 180mA 4.5V < VIN < 5.5V, FB = GND, ILOAD = 0 to 120mA 0.1V < VFB < (VIN - 0.1V) 0.1V < VFB < (VIN - 0.1V) VIN = 3V to 5.5V 4.8 11.5 1.96 VIN 0.5 0.4 1 10 1.1 60 0.5 500 300 10 80 4.3 8.6 0.7 0.25VIN 0.66VIN 1 0.1 VIN - 0.1 200 V V A V V nA CONDITIONS MIN 3.0 2.4 5.0 12.0 2.00 TYP MAX 5.5 2.8 5.2 12.5 2.04 12.5 UNITS V V V V V % A A k A A A s-A
2V < (VOUT + 0.5V - VIN) < 8V (see PulseFrequency-Modulation Control Scheme section) VIN = 3V VIN = 5.5V V SHDN = 0 or VIN VIN = 3V to 5.5V. For VFB below this voltage, output regulates to 12V. VIN = 3V to 5.5V. For VFB above this voltage, output regulates to 5V. VFB = 2.05V, VOUT = 13V
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Low-Profile, 5V/12V or Adjustable, Step-Up DC-DC Converters for Flash Memory/PCMCIA Cards
ELECTRICAL CHARACTERISTICS
(VIN = 3.3V, GND = PGND = FB = 0V, SHDN = IN, TA = -40C to +85C, unless otherwise noted.) (Note 2) PARAMETER Supply Voltage Undervoltage Lockout Threshold Output Voltage (Note 1) FB Regulation Setpoint Adjustable Output Voltage Range Switch On-Resistance Switch Off-Leakage Switch Current Limit SS Resistance Quiescent Supply Current Shutdown Quiescent Current OUT Input Current Switch On-Time Constant (K) Switch Off-Time Ratio SHDN Input Low Voltage SHDN Input High Voltage SHDN Input Current FB Input Low Voltage FB Input High Voltage FB Input Current V SHDN = VIN, VSS = 150mV V SHDN = VSS = 0 VOUT = 13V V SHDN = 0, OUT = IN VOUT = 13V 3V < VIN < 5.5V (tON = K / VIN) MAX606 MAX607 1.8 3.5 0.3 MAX606 MAX607 VLX = 12V 0.55 30 3V < VIN < 5V, FB = IN, ILOAD = 0 to 135mA 4.5V < VIN < 5.5V, FB = GND, ILOAD = 0 to 90mA 0.1V < VFB < (VIN - 0.1V) 0.1V < VFB < (VIN - 0.1V) 4.75 11.4 1.94 VIN CONDITIONS MIN 3.0 2.4 TYP MAX 5.5 2.8 5.25 12.6 2.06 12.5 1 10 1.25 60 0.5 500 300 10 85 4.5 9.0 0.7 0.25VIN 0.66VIN 1 0.1 VIN - 0.1 200 V V A V V nA UNITS V V V V V A A k A A A s-V
MAX606/MAX607
2V < (VOUT + 0.5V - VIN) < 8V (see PulseFrequency-Modulation Control Scheme section) VIN = 3V VIN = 5.5V V SHDN = 0 or VIN VIN = 3V to 5.5V. For VFB below this voltage, output regulates to 12V. VIN = 3V to 5.5V. For VFB above this voltage, output regulates to 5V. VFB = 2.05V, VOUT = 13V
Note 1: The load specification is guaranteed by DC parametric tests and is not production tested in circuit. Note 2: Specifications to -40C are guaranteed by design, not production tested.
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Low-Profile, 5V/12V or Adjustable, Step-Up DC-DC Converters for Flash Memory/PCMCIA Cards MAX606/MAX607
Typical Operating Characteristics
(VIN = 3.3V, TA = +25C, unless otherwise noted.)
MAXIMUM OUTPUT CURRENT vs. INPUT VOLTAGE
MAX606/07toc01
MAX606 EFFICIENCY vs. OUTPUT CURRENT
MAX606/7 TOC02
MAX607 EFFICIENCY vs. OUTPUT CURRENT
90 80 EFFICIENCY (%) 70 60 50 40 30 A: VOUT = 12V, VIN = 3.3V B: VOUT = 5V, VIN = 3.3V C: VOUT = 12V, VIN = 5V D: VOUT = 5V, VIN = 5V 0.01 0.1 1 10 100 1000 OUTPUT CURRENT (mA) CIN = 2 x 1F COUT = 4.7F B A D C
MAX606/7 TOC03 MAX606/07-09 MAX606/7 TOC-06
700 MAX606 (VOUT = 5V) MAXIMUM OUTPUT CURRENT (mA) 600 MAX607 (VOUT = 5V) 500
100 90 80 EFFICIENCY (%) 70 60 50 40 30
CIN = 2 x 1F COUT = 4.7F C A
100
D B
400 300 200 100 0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 INPUT VOLTAGE (V) MAX606 (VOUT = 12V) MAX607 (VOUT = 12V)
20 10 0 0.01 0.1 1
A: VOUT = 12V, VIN = 3.3V B: VOUT = 5V, VIN = 3.3V C: VOUT = 12V, VIN = 5V D: VOUT = 5V, VIN = 5V 10 100 1000 OUTPUT CURRENT (mA)
20 10 0
SHUTDOWN QUIESCENT CURRENT vs. TEMPERATURE
MAX606/7 TOC04
SWITCH ON-TIME vs. INPUT VOLTAGE
MAX606/7 TOC-05
SWITCH OFF-TIME vs. OUTPUT VOLTAGE
4000 3500 SWITCH OFF-TIME (ns) 3000 2500 D 2000 1500 1000 500 0 B A C A: MAX607, VIN = 5V B: MAX606, VIN = 5V C: MAX607, VIN = 3.3V D: MAX606, VIN = 3V
1.0 0.9 0.8 SHUTDOWN IQ (A) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
FOR VIN = 3V, 3.3V, AND 5V 5 MINUTE WAIT BEFORE MEASUREMENT
3000 2500 SWITCH ON-TIME (ns) 2000 1500 1000 500 0 2.5 MAX607
MAX606
-40
-20
0
20
40
60
80
3.0
3.5
4.0
4.5
5.0
5.5
2
3
4
5
6
7
8
9
10 11 12
TEMPERATURE (C)
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
MAX606 NO-LOAD SUPPLY CURRENT vs. TEMPERATURE
MAX606/7-07
MAX607 NO-LOAD SUPPLY CURRENT vs. TEMPERATURE
A: VOUT = 12V, MBR0520 DIODE B: VOUT = 12V, MBR0540 DIODE C: VOUT = 5V, MBR0520 DIODE D: VOUT = 5V, MBR0540 DIODE
MAX606/7-08
DIODE LEAKAGE CURRENT vs. TEMPERATURE
10,000 1000 LEAKAGE CURRENT (A) 100 10 1 0.1 0.01 VOUT = VANODE = 12V 0.001 MBR0530 MBR0520L MBR0540
10,000 NO-LOAD SUPPLY CURRENT (A)
1000 VIN = 3.3V
A B C D
NO-LOAD SUPPLY CURRENT (A)
A: VOUT = 12V, MBR0520 DIODE B: VOUT = 12V, MBR0540 DIODE C: VOUT = 5V, MBR0520 DIODE D: VOUT = 5V, MBR0540 DIODE
10,000
1000 VIN = 3.3V
A B C D
100 -40 -20 0 20 40 60 80 TEMPERATURE (C)
100 -40 -20 0 20 40 60 80 TEMPERATURE (C)
-40
-20
0
20
40
60
80
TEMPERATURE (C)
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Low-Profile, 5V/12V or Adjustable, Step-Up DC-DC Converters for Flash Memory/PCMCIA Cards
Typical Operating Characteristics (continued)
(VIN = 3.3V, TA = +25C, unless otherwise noted.)
MAX606 MAXIMUM OUTPUT CURRENT vs. INDUCTOR VALUE
MAX606/07-10
MAX606/MAX607
MAX607 MAXIMUM OUTPUT CURRENT vs. INDUCTOR VALUE
MAX606/07-11
START-UP DELAY vs. SOFT START CAPACITOR
1800 1600 START-UP DELAY (s) 1400 1200 1000 800 600 400 200 0 VIN = 3.3V C 1x101 1x102 1x103 1x104 D 1x105 A B A: MAX607 VOUT = 12V B: MAX606 VOUT = 12V C: MAX607 VOUT = 5V D: MAX606 VOUT = 5V
MAX606/07-12a
400 MAXIMUM OUTPUT CURRENT (mA) 350 300 250 200 150 100 50 0 1x100 INDUCTOR VALUE (H) A: VOUT = 5V, VIN = 3.3V B: VOUT = 12V, VIN = 5V C: VOUT = 12V, VIN = 3.3V C B A
400 MAXIMUM OUTPUT CURRENT (mA) 350 300 250 200 150 100 50 C A: VOUT = 5V, VIN = 3.3V B: VOUT = 12V, VIN = 5V C: VOUT = 12V, VIN = 3.3V A
20,800
B
1x101
0
1x100 INDUCTOR VALUE (H)
1x101
SOFT-START CAPACITOR (pF)
MAX606 START-UP DELAY AND INRUSH CURRENT
2V 12V
MAX607 START-UP DELAY AND INRUSH CURRENT
2V 12V
SHDN 2V/div OUTPUT 5V/div
SHDN 2V/div OUTPUT 5V/div
400mA INPUT 200mA/div 50s/div ILOAD = 1mA, INPUT = 3.3V, CSS = 10nF, COUT = 2 x 0.68F 200mA INPUT 200mA/div 100s/div ILOAD = 1mA, INPUT = 3.3V, CSS = 10nF, COUT = 4.7F
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Low-Profile, 5V/12V or Adjustable, Step-Up DC-DC Converters for Flash Memory/PCMCIA Cards MAX606/MAX607
Typical Operating Characteristics (continued)
(VIN = 3.3V, TA = +25C, unless otherwise noted.)
MAX606 LOAD-TRANSIENT RESPONSE
MAX607 LOAD-TRANSIENT RESPONSE
OUTPUT 50mV/div
OUTPUT 50mV/div
60mA OUTPUT 20mA/div OUTPUT 20mA/div
60mA
10s/div ILOAD = 5mA to 60mA, OUTPUT = 12V, INPUT = 3.3V
20s/div ILOAD = 5mA to 60mA, OUTPUT = 12V, INPUT = 3.3V
MAX606 LINE-TRANSIENT RESPONSE
MAX607 LINE-TRANSIENT RESPONSE
OUTPUT 100mV/div
OUTPUT 100mV/div
4V INPUT 500mV/div INPUT 500mV/div 100s/div ILOAD = 10mA, OUTPUT = 12V, INPUT = 3.3V TO 4.3V
4V
3V 50s/div ILOAD = 10mA, OUTPUT = 12V, INPUT = 3.3V TO 4.3V
3V
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Low-Profile, 5V/12V or Adjustable, Step-Up DC-DC Converters for Flash Memory/PCMCIA Cards
Pin Description
PIN NAME PGND FB FUNCTION Power Ground. Source of n-channel power MOSFET. Feedback Input. Connect to IN for 5V output, to GND for 12V output, or to a resistive voltage divider between OUT and GND for an adjustable output between IN and 12.5V. Shutdown Input, Active Low. Connect to GND to power down or to IN for normal operation. Output power FET is held off when SHDN is low. Supply Voltage Input: 3.0V to 5.5V Analog Ground Soft-Start Input Output. Always connect directly to the circuit output. Drain of n-channel power MOSFET
MAX606/MAX607
1
2
3 4 5 6 7 8
SHDN IN GND SS OUT LX
+5V INPUT C1 C2 L1 IN ON/OFF SHDN SS MAX606 FB GND LX C3 D1 OUTPUT 12V @ 120mA
+3.3V INPUT C1 C2 L1 FB SHDN IN LX C3 D1 OUTPUT 5V @ 180mA
ON/OFF
C4
MAX607 OUT
PGND
C4
SS MAX607 OUT GND PGND
MAX606
Figure 1. 12V Standard Application Circuit
Figure 2. 5V Standard Application Circuit
Standard Application Circuits
This data sheet provides two predesigned standard application circuits. The circuit of Figure 1 produces 12V at 120mA from a 5V input. Table 1 lists component values and part numbers for both the MAX606 and MAX607 variations of this circuit. The circuit of Figure 2 produces
5V at a typical output current of 180mA from a 3.3V input. Each application circuit is designed to deliver the full rated output load current over the temperature range listed. Component values and part numbers for this circuit are listed in Table 2. See Table 3 for component suppliers' phone and fax numbers.
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Low-Profile, 5V/12V or Adjustable, Step-Up DC-DC Converters for Flash Memory/PCMCIA Cards MAX606/MAX607
Table 1. Suggested Components for 12V Standard Application Circuit of Figure 2
DESIGNATION L1 D1 C1 C2 MAX606 5H inductor Dale ILS-3825-XX 0.5A, 20V diode Motorola MBR0520L 0.1F ceramic cap. MAX607 10H inductor Sumida CLS62-100 0.5A, 20V diode Motorola MBR0520L 0.1F ceramic cap.
Table 2. Suggested Components for 5V Standard Application Circuit of Figure 1
DESIGNATION L1 D1 C1 C2 MAX606 5H, 1A inductor Dale ILS-3825-XX 0.5A, 20V diode Motorola MBR0520L 0.1F ceramic cap. MAX607 10H, 0.7A inductor Sumida CLS62B-100 0.5A, 20V diode Motorola MBR0520L 0.1F ceramic cap.
2 x 0.68F ceramic cap. 2.2F ceramic cap. Marcon Marcon THCR20E1E684Z THCR30E1E225M 2 x 0.68F ceramic cap. 2 x 1F ceramic cap. Marcon Marcon THCR20E1E684Z THCR30E1E105M 10nF ceramic cap. 10nF ceramic cap.
2 x 0.68F ceramic cap. 2.2F ceramic cap. Marcon Marcon THCR20E1E684Z THCR30E1E225M 4.7F ceramic cap. Marcon THCR30E1E475M 10nF ceramic cap. 4.7F ceramic cap. Marcon THCR30E1E475M 10nF ceramic cap.
C3 C4
C3 C4
Detailed Description
The remainder of this document contains the detailed information you'll need to design a circuit that differs from the two Standard Application Circuits. If you are using one of the predesigned circuits, the following sections are purely informational. The MAX606/MAX607 CMOS, step-up DC-DC converters employ a current-limited pulse-frequency control scheme. This control scheme regulates a boost topology to convert input voltages between 3V and 5.5V into either a pin-programmable 5V/12V output, or an adjustable output between VIN and 12.5V. It optimizes performance over all input and output voltages, and guarantees output accuracy to 4%. The ultra-high switching frequency (typically 1MHz for the MAX606 and 0.5MHz for the MAX607) permits the use of extremely small external components, making these converters ideal for use in Types 1, 2, and 3 flash memory and PCMCIA applications.
Table 3. Component Suppliers
SUPPLIER Dale Inductors Marcon/United Chemi-Con Motorola Sumida USA Sumida Japan PHONE 605-668-4131 708-696-2000 602-244-3576 708-956-0666 03-607-5111 FAX 605-665-1627 708-518-9985 602-244-4015 708-956-0702 03-607-5144
Pulse-Frequency-Modulation Control Scheme
The MAX606/MAX607 employ a proprietary, currentlimited control scheme that combines the ultra-low supply current of traditional pulse-skipping converters with the high full-load efficiency of current-mode pulsewidth-modulation converters. This particular control scheme is similar to the one used in previous currentlimited devices (which governed the switching current
via maximum on-time, minimum off-time, and current limit), except it varies the on and off times according to the input and output voltages. This important feature enables the MAX606/MAX607 to achieve ultra-high switching frequencies while maintaining high output accuracy, low output ripple, and high efficiency over a wide range of loads and input/output voltages. Figure 3 shows the functional diagram of the MAX606/ MAX607. The internal power MOSFET is turned on when the error comparator senses that the output is out of regulation. The power switch stays on until either the timing circuit turns it off at the end of the on-time, or the switch current reaches the current limit. Once off, the switch remains off during the off-time. Subsequently, if the output is still out of regulation, another switching cycle is initiated. Otherwise, the switch remains turned off as long as the output is in regulation.
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Low-Profile, 5V/12V or Adjustable, Step-Up DC-DC Converters for Flash Memory/PCMCIA Cards MAX606/MAX607
IN
TIMING CIRCUIT tOFF tON EN ON INH CONTROL LOGIC INTERNAL POWER 1 SWITCH RLIM
LX
DRIVER
UNDERVOLTAGE LOCKOUT
OFF
CURRENT-LIMIT COMPARATOR
PGND SS VREF OUT
MAX606 MAX607
SHDN
REF
ERROR COMPARATOR
INT/EXT FB FB DUAL MODE 5V/12V
Figure 3. Functional Diagram
The on/off times are determined by the input and output voltages: tON = K / VIN tOFF = 0.5 * K / (VOUT + VDIODE - VIN) K is typically 3s-V for the MAX606 and 6s-V for the MAX607. This factor is chosen to set the optimum switching frequency and the one-cycle current limit, which determines the no-load output ripple at low output-to-input voltage differentials. The factor of 0.5 in the off-time equation is the typical switch off-time ratio. This ratio guarantees high efficiency under a heavy load by allowing the inductor to operate in continuous-conduction mode. For example, a switch off-time ratio of 1 would cause the device to operate on the edge of discontinuous-conduction mode.
To determine the actual switch off-time ratio for a particular device, measure tON, tOFF, VIN, and VOUT, and then solve for the ratio by substituting these values into the off-time equation. Unlike PWM converters, the MAX606/MAX607 generate variable-frequency switching noise. However, the amplitude of this noise does not exceed the product of the switch current limit and the output capacitor equivalent series resistance (ESR). Traditional clocked-PFM or pulse-skipping converters cannot make this claim.
Output Voltage Selection
The MAX606/MAX607 output voltage is pin-programmable to 5V and 12V, and also adjustable to voltages between VIN and 12.5V. Connect FB to IN for a 5V output, to GND for a 12V output, or to a resistive divider between the output and GND for an adjustable output. Always connect OUT to the output.
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Low-Profile, 5V/12V or Adjustable, Step-Up DC-DC Converters for Flash Memory/PCMCIA Cards MAX606/MAX607
INPUT
IN LX 10pF OUTPUT R1
MAX606 MAX607 OUT
FB GND PGND
SS Capacitor graph in the Typical Operating Characteristics shows typical timing characteristics for selected capacitor values and circuit conditions. The soft-start capacitor is discharged each time the MAX606 or MAX607 is put into shutdown, including during undervoltage lockout and when powering down at IN. If the circuit is required to start up with no load, as in flash memory programming supplies, soft-start is not required. Omitting the soft-start capacitor permits a minimum output voltage rise time from the shutdown state, improving flash memory access time.
Undervoltage Lockout
R2 VOUT = VREF VREF = 2V
(
R1 + 1) R2
Figure 4. Adjustable Output Voltage
When FB is connected to IN or GND, an internal voltage divider is configured to produce a predetermined output. However, when the voltage at FB is between 0.1V above ground and 0.1V below VIN, the device is in the adjustable output mode. In this mode, the MAX606/MAX607 output voltage is set by two external resistors, R1 and R2 (Figure 4), which form a voltage divider between the output and FB. Use the following equation to determine the output voltage: VOUT = VREF (R1 / R2 + 1) where VREF = 2V. To simplify the resistor selection: R1 = R2 [(VOUT / VREF) - 1] Since the input current at FB is 200nA maximum, large values (up to 100k) can be used for R2 with no significant loss of accuracy. For 1% error, the current through R2 should be at least 100 times the FB input bias current.
The MAX606/MAX607 monitor the supply voltage at IN and operate for supply voltages greater than 2.8V. When an undervoltage condition is detected, control logic turns off the output power FET and discharges the soft-start capacitor to ground. The control logic holds the output power FET in an off state until the supply voltage rises above the undervoltage threshold, at which time a soft-start cycle begins.
Shutdown Mode
Connecting SHDN to GND will hold the MAX606/ MAX607 in shutdown mode. In shutdown, the output power FET is off, but there is still an external path from IN to the load via the inductor and diode. The internal reference also turns off, which causes the soft-start capacitor to discharge. Typical device standby current in shutdown mode is 0.01A. For normal operation, connect SHDN to IN. A soft-start cycle is initiated when the MAX606/MAX607 exit shutdown.
Applications Information
Inductor Selection
Use a 5H inductor for the MAX606 and a 10H inductor for the MAX607. See Table 3 for a list of component suppliers. Higher inductor values allow greater load currents due to operation in continuous-conduction mode, while lower inductor values lead to smaller physical size due to lower energy-storage requirements and lower output-filter-capacitor requirements. Potential drawbacks of using lower inductor values are increased output ripple, lower efficiency, and lower output-current capability due to operation in discontinuous-conduction mode. (See the Maximum Output Current vs. Inductor Value graph in the Typical Operating Characteristics.) The inductor must have a saturation (incremental) current rating equal to the peak switch-current limit, which is 1.1A. For highest efficiency, minimize the inductor's DC resistance.
Soft-Start
Connecting a capacitor to the Soft-Start (SS) pin ensures a gradually increasing current limit during power-up or when exiting shutdown, thereby reducing initial inrush currents. This feature can be useful, for example, when an old battery's increased series resistance limits initial inrush currents. Using the soft-start feature in a situation like this minimizes the risk of overloading the incoming supply. Soft-start timing is controlled by the value of the SS capacitor. On power-up, the SS capacitor is charged by the 2V reference through an internal, 45k pull-up resistor. As the voltage on the SS pin increases, the voltage at the SS clamp output also increases, which in turn raises the current-limit threshold. The Start-Up Delay vs.
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Low-Profile, 5V/12V or Adjustable, Step-Up DC-DC Converters for Flash Memory/PCMCIA Cards
Diode Selection
The MAX606/MAX607's high switching frequency demands a high-speed rectifier. Use a Schottky diode with at least a 0.5A average current rating and a 1.2A peak current rating, such as an MBR0520L. See Table 3 for a list of component suppliers.
___________________Chip Topography
PGND LX
MAX606/MAX607
Capacitor Selection
Output Filter Capacitor The output voltage ripple is a function of the output capacitor's equivalent series resistance (ESR) and capacitance. For best performance, use ceramic capacitors. Higher-ESR capacitors, such as tantalums, will cause excessive ripple. See Table 3 for a list of component suppliers. The output voltage ripple is approximately 100mVp-p for the 12V Standard Application Circuit (Figure 1) and 50mV for the 5V circuit (Figure 2). To further reduce this ripple, or to reduce the ripple on a different application circuit, increase the value of the output filter capacitor. If this capacitor is low ESR (e.g., ceramic), the output voltage ripple will be dominated by this capacitance. Input Bypass Capacitors For applications where the MAX606/MAX607 are physically close to the input supply's filter capacitor (e.g., in PCMCIA drivers from the host computer), the input bypass capacitor may not be necessary.
In other applications where the MAX606/MAX607 are more than a few inches away from the supply (such as memory cards), the input bypass capacitor is needed to reduce reflected current ripple to the supply and improve efficiency by creating a low-impedance path for the ripple current. Under these circumstances, the associated high Q and low ESR of ceramic capacitors do not diminish the problem. Therefore, include some low-Q, moderate-ESR capacitance (e.g., tantalum) at the input in order to reduce ringing.
PGND
LX
PGND
LX
0.084" (2.134mm)
SEL OUT SHDN V+ GND 0.058" (1.473mm) SS
TRANSISTOR COUNT: 613 SUBSTRATE CONNECTED TO GND
Layout
The MAX606/MAX607's high-frequency operation and high peak currents make PC board layout critical to minimize ground bounce and noise. Locate input bypass and output filter capacitors as close to the device pins as possible. All connections to OUT (and to FB when operating in adjustable-output mode) should also be kept as short as possible. A ground plane is recommended. Solder GND and PGND directly to the ground plane. Refer to the MAX606/MAX607 evaluation kit manual for a suggested surface-mount layout.
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Low-Profile, 5V/12V or Adjustable, Step-Up DC-DC Converters for Flash Memory/PCMCIA Cards MAX606/MAX607
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8LUMAXD.EPS
12
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Price & Availability of MAX607

	To Download MAX607 Datasheet File
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