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19-0177; Rev 1; 8/98
3.3V-Input to Regulated 5V-Output Charge Pumps
General Description
The MAX682/MAX683/MAX684 charge-pump regulators generate 5V from a 2.7V to 5.5V input. They are specifically designed to serve as high-efficiency auxiliary supplies in applications that demand a compact design. The MAX682, MAX683, and MAX684 deliver 250mA, 100mA, and 50mA output current, respectively. These complete 5V regulators require only one resistor and three external capacitors--no inductors are needed. High switching frequencies (externally adjustable up to 2MHz) and a unique regulation scheme allow the use of capacitors as small as 1F per 100mA of output current. The MAX683/MAX684 are offered in a spacesaving 8-pin MAX package that is only 1.1mm high, while the MAX682 is available in an 8-pin SO.
Features
o Ultra-Small: 1F Capacitors per 100mA of Output Current o No Inductors Required o 1.1mm Height in MAX Package (MAX683/MAX684) o Up to 250mA Output Current (MAX682) o Regulated 4% Output Voltage o 50kHz to 2MHz Adjustable Switching Frequency o 2.7V to 5.5V Input Voltage o 100A Quiescent Current in Pulse-Skipping Mode o 0.1A Shutdown Current
MAX682/MAX683/MAX684
Applications
Flash Memory Supplies Battery-Powered Applications Miniature Equipment PCMCIA Cards 3.3V to 5V Local Conversion Applications Backup-Battery Boost Converters 3V to 5V GSM SIMM Cards
PART MAX682ESA MAX683EUA MAX684EUA
Ordering Information
TEMP. RANGE -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 8 SO 8 MAX 8 MAX
Typical Operating Circuit
TOP VIEW
CXN INPUT 2.7V TO 5.5V REXT CXP
SKIP 1 8 7
Pin Configurations
OUT CXP CXN PGND
SKIP 1 SHDN IN 2 3
8 7
OUT CXP CXN PGND
MAX682
IN SKIP SHDN GND PGND OUT
OUTPUT 5V/250mA
SHDN IN
2
MAX682
3 6 5 GND 4 GND 4
MAX683 MAX684
6 5
SO
MAX
________________________________________________________________ Maxim Integrated Products
1
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3.3V-Input to Regulated 5V-Output Charge Pumps MAX682/MAX683/MAX684
ABSOLUTE MAXIMUM RATINGS
IN, OUT, SHDN, SKIP to GND.................................-0.3V to +6V PGND to GND.....................................................................0.3V CXN to GND ................................................-0.3V to (VIN + 0.3V) CXP to GND..............................................-0.3V to (VOUT + 0.3V) Continuous Output Current MAX682........................................................................300mA MAX683........................................................................150mA MAX684..........................................................................75mA Output Short-Circuit Duration ...............................................5sec Continuous Power Dissipation (TA = +70C) 8-Pin SO (derate 5.9mW/C above +70C).................471mW 8-Pin MAX (derate 4.1mW/C above +70C) ............330mW Operating Temperature Range MAX68_E_A ....................................................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +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 = 3V, V SKIP = 0V, CIN = 1F, CX = 0.47F, COUT = 2F, I SHDN = 22A; IMAX = 250mA for MAX682, IMAX = 100mA for MAX683, IMAX = 50mA for MAX684; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER Input Voltage Range Input Undervoltage Lockout Threshold Input Undervoltage Lockout Hysteresis Output Voltage VOUT 0 < ILOAD IMAX; 3.0V IN 3.6V for SKIP = 0, 3.0V IN 3.6V for SKIP = 0, 3.0V IN 5.5V for SKIP = IN MAX682 Maximum Output Current IMAX MAX683 MAX684 SKIP = 0, VIN = 3.6V No-Load Input Current IQ MAX682 SKIP = VIN = 3.6V MAX683 MAX684 Load Regulation SHDN Logic Low Input SHDN On Bias Voltage SHDN Input Current Range VLDR VINL, SHDN VON, SHDN TA = +25C ISHDN (Note 2) ISHDN = 22A Switching Frequency (Note 2) ISHDN =4.4A Shutdown Supply Current Shutdown Exit Time IQ, SHDN tSTART 0C < TA < +85C -40C < TA < +85C 0C < TA < +85C -40C < TA < +85C 630 1 850 750 160 150 1000 1000 200 200 0.1 50 690 SKIP = high, 0 ILOAD IMAX 4.80 250 100 50 0.1 7.5 2.5 1.7 -3 0.35 750 50 1200 1300 250 270 5 A s kHz % V mV A 0.18 mA mA SYMBOL VIN CONDITIONS Regulation with VIN > 3.6V requires SKIP = high MIN 2.7 2.0 2.35 100 TYP MAX 5.5 2.6 UNITS V V mV
5.05
5.20
V
SHDN = 0, VIN = 5.5V, VOUT = 0 RL = 5V/IMAX
2
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3.3V-Input to Regulated 5V-Output Charge Pumps
ELECTRICAL CHARACTERISTICS (continued)
(VIN = 3V, V SKIP = 0V, CIN = 1F, CX = 0.47F, COUT = 2F, ISHDN = 22A; IMAX = 250mA for MAX682, IMAX = 100mA for MAX683, IMAX = 50mA for MAX684; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER SKIP Input Voltage Low SKIP Input Voltage High SKIP Input Leakage Current SYMBOL VINL, SKIP VINH, SKIP ISKIP VIN = 5.5V VIN = 5.5V, V SKIP = 0V or 5.5V 2.4 -1 1 CONDITIONS MIN TYP MAX 0.8 UNITS V A
MAX682/MAX683/MAX684
Note 1: Specifications to -40C are guaranteed by design and not production tested. Note 2: Current into SHDN determines oscillator frequency: REXT (k) = 45000 (VIN - 0.69V) / fOSC (kHz)
__________________________________________Typical Operating Characteristics
(Circuit of Figure 5, VIN = 3.3V, component values from Tables 2 and 3, TA = +25C, unless otherwise noted.)
NO-LOAD SUPPLY CURRENT vs. SUPPLY VOLTAGE
SKIP = HIGH ISHDN = 22A 8 SUPPLY CURRENT (mA) MAX682 6
MAX682 TOC01
OUTPUT VOLTAGE vs. LOAD CURRENT (SKIP = LOW)
MAX682 TOC03
OUTPUT VOLTAGE vs. LOAD CURRENT (SKIP = HIGH)
SKIP = HIGH ISHDN = 22A
MAX682 TOC04
10
5.50 5.25 OUTPUT VOLTAGE (V) 5.00 4.75 4.50 4.25
5.50 5.25 OUTPUT VOLTAGE (V) 5.00 4.75 4.50 4.25 4.00 MAX684 MAX683 MAX682
MAX684 MAX682 MAX683
4 MAX683 2 MAX684 0 2 3 4 SUPPLY VOLTAGE (V) 5 6
4.00 1 10 100 1000 LOAD CURRENT (mA)
1
10
100
1000
LOAD CURRENT (mA)
OUTPUT VOLTAGE vs. SUPPLY VOLTAGE
MAX682 TOC06
OSCILLATOR FREQUENCY vs. SHUTDOWN PIN INPUT CURRENT
MAX682 TOC08
NO-LOAD SUPPLY CURRENT vs. SHUTDOWN PIN INPUT CURRENT
SKIP = HIGH NO-LOAD SUPPLY CURRENT (mA) MAX682 10 MAX683
MAX682 TOC09
5.50 SKIP = LOW 5.25 OUTPUT VOLTAGE (V) 5.00 4.75 4.50 4.25 4.00 3.75 3.50 2 3 4 SUPPLY VOLTAGE (V) 5 6 SKIP = HIGH
10M
100
OSCILLATOR FREQUENCY (Hz)
1M
100k
1
MAX684 10k 0.1 1 10 100 SHDN INPUT CURRENT (A) 0.1 0.1 1 10 100 SHDN INPUT CURRENT (A)
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3.3V-Input to Regulated 5V-Output Charge Pumps MAX682/MAX683/MAX684
Typical Operating Characteristics (continued)
(Circuit of Figure 5, VIN = 3.3V, component values from Tables 2 and 3, TA = +25C, unless otherwise noted.)
MAX682 EFFICIENCY vs. LOAD CURRENT (SKIP = LOW)
MAX682 TOC10
MAX683 EFFICIENCY vs. LOAD CURRENT (SKIP = LOW)
MAX682 TOC11
MAX684 EFFICIENCY vs. LOAD CURRENT (SKIP = LOW)
90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 VIN = 3.3V VIN = 3.6V VIN = 3.0V
MAX682 TOC12
100 90 80 EFFICIENCY (%) VIN = 3.0V
100 90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 VIN = 3.3V VIN = 3.6V VIN = 3.0V
100
70 60 50 40 30 20 10 0 0.1 1 10 100 1000 LOAD CURRENT (mA) VIN = 3.3V VIN = 3.6V
0.1
1
10
100
1000
0.1
1
10
100
LOAD CURRENT (mA)
LOAD CURRENT (mA)
MAX682 EFFICIENCY vs. LOAD CURRENT (SKIP = HIGH)
MAX682 TOC13
MAX683 EFFICIENCY vs. LOAD CURRENT (SKIP = HIGH)
90 80 EFFICIENCY (%) EFFICIENCY (%) 70 60 50 40 30 20 VIN = 5.0V VIN = 3.3V VIN = 3.0V
MAX682 TOC14
MAX684 EFFICIENCY vs. LOAD CURRENT (SKIP = HIGH)
80 70 60 50 40 30 20 VIN = 5.0V VIN = 3.0V VIN = 3.3V
MAX682 TOC15
100 90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 1 10 100 ISHDN = 22A VIN = 5.0V VIN = 3.3V VIN = 3.0V
100
90
10 0 1000 1 10
ISHDN = 22A 100 1000
10 0 1 10
ISHDN = 22A 100
LOAD CURRENT (mA)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
OUTPUT WAVEFORM (SKIP = HIGH)
MAX682 TOC16
OUTPUT WAVEFORM (SKIP = LOW)
MAX682 TOC17
50mV/div
50mV/div
200ns/div SKIP = HIGH, ISHDN = 22A, ILOAD = 250mA, MAX682
200ns/div SKIP = LOW, ILOAD = 250mA, MAX682
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3.3V-Input to Regulated 5V-Output Charge Pumps
Typical Operating Characteristics (continued)
(Circuit of Figure 5, VIN = 3.3V, component values from Tables 2 and 3, TA = +25C, unless otherwise noted.)
MAX682/MAX683/MAX684
SHUTDOWN TIMING
MAX682 TOC18
LINE-TRANSIENT RESPONSE
MAX682 TOC20
LOAD-TRANSIENT RESPONSE
MAX682 TOC19
A
A
A
B B
B
100s/div A: OUTPUT VOLTAGE: SKIP = HIGH, RL = 5V / IMAX, 2V/div B: SHDN VOLTAGE: 1V/div
2ms/div A: INPUT VOLTAGE: VIN = 3.1V TO 3.6V, 500mV/div B: OUTPUT VOLTAGE: SKIP = HIGH, ISHDN = 22A, ILOAD = 250mA, 50mV/div, MAX682
2ms/div A: LOAD CURRENT: ILOAD = 5mA TO 250mA, 500mA/div B: OUTPUT VOLTAGE: SKIP = HIGH, ISHDN = 22A, 100mV/div, MAX682
Pin Description
PIN 1 NAME SKIP FUNCTION When SKIP = low, the regulator operates in low-quiescent-current skip mode. When SKIP = high, the regulator operates in constant-frequency mode, minimizing output ripple and noise. SKIP must be tied high for input voltages above 3.6V. Shutdown Input. Drive SHDN through an external resistor. When SHDN = low, the device turns off. When current is sourced into SHDN through REXT, the device activates, and the SHDN pin input current sets the oscillator's switching frequency. REXT (k) = 45000 (V IN - 0.69V) / fOSC (kHz). Input Supply Pin. Can range from 2.7V to 5.5V for SKIP = high, and 2.7V to 3.6V for SKIP = low. Bypass to PGND with a suitable value capacitor (see Capacitor Selection section). Ground Pin. Connect to PGND through a short trace. Power Ground Pin Negative Terminal of the Charge-Pump Transfer Capacitor Positive Terminal of the Charge-Pump Transfer Capacitor Fixed 5V Power Output. Bypass to PGND with output filter capacitor.
2
SHDN
3 4 5 6 7 8
IN GND PGND CXN CXP OUT
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3.3V-Input to Regulated 5V-Output Charge Pumps MAX682/MAX683/MAX684
Detailed Description
The MAX682/MAX683/MAX684 charge pumps provide a regulated 5V output from a 2.7V to 5.5V input. They deliver a maximum of 250mA, 100mA, or 50mA load current, respectively. Designed specifically for compact applications, a complete regulator circuit requires only three small external capacitors and one resistor. An externally adjustable switching frequency and innovative control scheme allow the circuit to be optimized for efficiency, size, or output noise. The devices also contain a shutdown feature. The MAX682/MAX683/MAX684 consist of an error amplifier, a 1.23V bandgap reference, an internal resistive feedback network, an oscillator, high-current MOSFET switches, and shutdown and control logic (Figure 1). Figure 2 shows an idealized unregulated chargepump voltage doubler. The oscillator runs at a 50% duty cycle. During one half of the period, the transfer capacitor (CX) charges to the input voltage. During the other half, the doubler stacks the voltage across CX and the input voltage, and transfers the sum of the two voltages to the output filter capacitor (COUT). Rather than simply doubling the input voltage, the MAX682/MAX683/MAX684 provide a regulated fixed output voltage (5V) using either skip mode or constantfrequency mode. Skip mode and constant-frequency mode are externally selected via the SKIP input pin.
OUT IN
IN
S2
OUT
S1
CX
CIN
COUT OSC
Figure 2. Unregulated Voltage Doubler
IN
S2
OUT
S1
CX
CIN EN OSCILLATOR
Figure 3. Skip-Mode Regulation
Skip Mode
1.23V SKIP CONTROL LOGIC SHDN SHDN EN OSC SWITCHES CXN CXP
In skip mode (SKIP = low), the error amplifier disables switching when it detects an output higher than 5V. The device then skips switching cycles until the output voltage drops. Then the error amplifier reactivates the oscillator. Figure 3 illustrates the regulation scheme. This regulation method minimizes operating current because the device does not switch continuously. SKIP is a logic input and should not remain floating.
Constant-Frequency Mode
PGND
Figure 1. Functional Block Diagram
6
When SKIP is high, the charge pump runs continuously at the selected frequency. Figure 4 shows a block diagram of the device in constant-frequency mode. The error amplifier controls the charge on CX by driving the gate of the N-channel FET. When the output voltage falls, the gate drive increases, resulting in a larger voltage across CX. This regulation scheme minimizes output ripple. Since the device switches continuously, the
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3.3V-Input to Regulated 5V-Output Charge Pumps
IN S2 CX S1 CIN OSC COUT N-CHANNEL OUT
Figure 4. Constant-Frequency-Mode Regulation
Table 1. Tradeoffs Between Operating Modes
FEATURE Best Light-Load Efficiency Smallest External Component Size Output Ripple Amplitude and Frequency Load Regulation Relatively large amplitude, variable frequency Very Good Relatively small amplitude, constant frequency Good SKIP MODE (SKIP = LOW) CONSTANTFREQUENCY MODE (SKIP = HIGH)
max) of supply current in this mode and the output presents a 50k impedance to ground. The device exits shutdown once SHDN is forward biased (minimum of 1A of current). The typical no-load shutdown exit time is 50s. When SHDN is pulled high through an external resistor to V IN , the bias current into SHDN determines the charge-pump frequency. To select the frequency, calculate the external resistor value, REXT, using the following formula: REXT = 45000 (VIN - 0.69V) / fOSC where REXT is in k and fOSC is in kHz. Program the frequency in the 50kHz to 2MHz range. This frequency range corresponds to SHDN input currents between 1A and 50A. Proper operation of the oscillator is not guaranteed beyond these limits. Currents lower than 1A may shut down the device. The forward-biased diode voltage from the SHDN input to GND has a temperature coefficient of -2mV/C.
MAX682/MAX683/MAX684
Undervoltage Lockout
The MAX682/MAX683/MAX684 have an undervoltagelockout feature that deactivates the devices when the input voltage falls below 2.25V. Regulation at low input voltages cannot be maintained. This safety feature ensures that the device shuts down before the output voltage falls out of regulation by a considerable amount (typically 10% with no load). Once deactivated, hysteresis holds the device in shutdown until the input voltage rises 100mV above the lockout threshold.
Applications Information
Capacitor Selection
The MAX682/MAX683/MAX684 require only three external capacitors (Figure 5). Their values are closely linked to the output current capacity, oscillator frequency, output noise content, and mode of operation. Generally, the transfer capacitor (CX) will be the smallest, and the input capacitor (CIN) is twice as large as C X . Higher switching frequencies allow the use of smaller CX and CIN. The output capacitor (COUT) can be anywhere from 5-times to 50-times larger than CX, depending on the mode of operation and ripple tolerance. In continuous switching mode, smaller output ripple allows smaller COUT. In skip mode, a larger COUT is required to maintain low output ripple. Tables 2 and 3 show capacitor values recommended for lowest supply-current operation (skip mode) and smallest size operation (constant-frequency mode), respectively.
output noise contains well-defined frequency components, and the circuit requires much smaller external capacitors for a given output ripple. However, constantfrequency mode, due to higher operating current, is less efficient at light loads than skip mode. Note: For input voltages above 3.6V, the devices must operate in constant-frequency mode. Table 1 summarizes the tradeoffs between the two operating modes.
Frequency Selection and Shutdown
The SHDN pin on the MAX682/MAX683/MAX684 performs a dual function: it shuts down the device and determines the oscillator frequency. The SHDN input looks like a diode to ground and should be driven through a resistor. Driving SHDN low places the device in shutdown mode. This disables all switches, the oscillator, and control logic. The device typically draws 0.1A (5A
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7
3.3V-Input to Regulated 5V-Output Charge Pumps MAX682/MAX683/MAX684
Table 2. Recommended Capacitor Values for Quiescent Current (Skip Mode)
VOUT COUT (F) OUTPUT CIN CX PART RIPPLE (mA) (F) (F) TANTALUM CERAMIC (mV) MAX682 MAX683 250 100 2.2 1 1 0.47 47 22 10 4.7 100 100
OFF ON VON REXT IN CXP 2 3 1 CIN SHDN IN SKIP GND 4 PGND 5 7 6 8 CX
MAX682 MAX683 MAX684
CXN OUT
OUT COUT
MAX684
50
0.47 0.22
10
2.2
100
Figure 5. Standard Operating Circuit
5V/500mA
Table 3. Recommended Capacitor Values for Smallest Size (Constant-Frequency Mode, ISHDN = 22A, 1MHz)
PART OUTPUT (mA) 250 100 CIN (F) 1 0.47 CX (F) 0.47 0.22 CERAMIC COUT (F) 2.2 1 VOUT RIPPLE (mV)
3.3VIN
IN SKIP 100k 1F
OUT
IN SKIP 100k 1F
OUT
MAX682
SHDN CXP
MAX682
SHDN CXP 4.7F
MAX682 MAX683
80 80
0.47F
CXN GND PGND
0.47F
CXN GND PGND
MAX684
50
0.22
0.1
0.47
80
Figure 6. Paralleling Two MAX682s
Table 4. Recommended Capacitor Manufacturers
VALUE DESCRIPTION MANUFACTURER PHONE NUMBER
47F to 10F 47F to 10F 0.1F to 2.2F
595D-series tantalum surface mount TPS-series surface mount Ceramic surface mount
where ESRCOUT is the ESR of the output filter capacitance, and RTX is the open-loop output transfer resistance of the IC. RTX is typically 0.8 for the MAX682, 1.6 for the MAX683, and 3 for the MAX684. In constant-frequency mode, output ripple is dominated by COUT and is approximately: VRIPPLE(const-freq) IOUT / (2 x fOSC x COUT) All capacitors must maintain a low (<100m) equivalent series resistance (ESR). Table 4 lists the manufacturers of recommended capacitors. Surface-mount tantalum capacitors will work well for most applications. Ceramic capacitors will provide the lowest ripple due to their typically lower ESR. If the source impedance or inductance of the input supply is large, additional input bypassing (2.2F to 22F) may be needed. This additional capacitance need not be a low-ESR type.
Sprague
(603) 224-1961
AVX TDK
(803) 946-0690 (847) 390-4373
In addition, the following two equations approximate output ripple for each mode. In skip mode, output ripple is dominated by ESR, and is approximately: VRIPPLE(SKIP) (2VIN - VOUT)ESRCOUT / RTX
8
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3.3V-Input to Regulated 5V-Output Charge Pumps MAX682/MAX683/MAX684
Power Dissipation
The power dissipated in the MAX682/MAX683/MAX684 depends on output current and is accurately described by: PDISS = IOUT (2VIN - VOUT) PDISS must be less than that allowed by the package rating. See the Absolute Maximum Ratings for 8-pin MAX (MAX683/MAX684) and SO (MAX682) powerdissipation limits and deratings.
Paralleling Devices
The MAX682/MAX683/MAX684 can be paralleled to yield higher load currents. The circuit of Figure 6 can deliver 500mA at 5V. It uses two MAX682s in parallel. The devices can share the output capacitors, but each one requires its own transfer capacitor (CX) and input capacitor. For best performance, the paralleled devices should operate in the same mode (skip or constant frequency).
Layout Considerations
All capacitors should be soldered in close proximity to the IC. Connect ground and power ground through a short, low-impedance trace. If a high-value resistor is driving the shutdown input and is picking up noise (i.e., frequency jitter at CXP and CXN), bypass SHDN to GND with a small capacitor (0.01F).
Chip Information
TRANSISTOR COUNT: 659 SUBSTRATE CONNECTED TO GND
Package Information
8LUMAXD.EPS
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9
3.3V-Input to Regulated 5V-Output Charge Pumps MAX682/MAX683/MAX684
Package Information
SOICN.EPS
10
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3.3V-Input to Regulated 5V-Output Charge Pumps MAX682/MAX683/MAX684
NOTES
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11
3.3V-Input to Regulated 5V-Output Charge Pumps MAX682/MAX683/MAX684
NOTES
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.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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