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19-0253; Rev 1; 8/94
UAL IT MAN TION K T VALUA A SHEE E T WS DA FOLLO
+12V, 30mA Flash Memory Programming Supply
____________________________Features
o Regulated +12V 5% Output Voltage o 4.5V to 5.5V Supply Voltage Range o Fits in 0.1in2 o Guaranteed 30mA Output o No Inductor--Uses Only 4 Capacitors o 185A Quiescent Current o Logic-Controlled 0.5A Shutdown o 8-Pin Narrow SO and DIP Packages
_______________General Description
The MAX662A is a regulated +12V, 30mA-output, chargepump DC-DC converter. It provides the necessary +12V 5% output to program byte-wide flash memories, and requires no inductors to deliver a guaranteed 30mA output from inputs as low as 4.75V. It fits into less than 0.1in2 of board space. The MAX662A is a pin-compatible upgrade to the MAX662, and is recommended for new designs. The MAX662A offers lower quiescent and shutdown currents, and guarantees the output current over all temperature ranges. The MAX662A is the first charge-pump boost converter to provide a regulated +12V output. It requires only a few inexpensive capacitors, and the entire circuit is completely surface-mountable. A logic-controlled shutdown pin that interfaces directly with microprocessors reduces the supply current to only 0.5A. The MAX662A comes in 8-pin narrow SO and DIP packages. For higher-current flash memory programming solutions, refer to the data sheets for the MAX734 (120mA output current, guaranteed) and MAX732 (200mA output current, guaranteed) PWM, switch-mode DC-DC converters. Or, refer to the MAX761 data sheet for a 150mA, PFM switch-mode DC-DC converter that operates from inputs as low as 2V.
MAX662A
______________Ordering Information
PART MAX662ACPA MAX662ACSA MAX662AC/D MAX662AEPA MAX662AESA MAX662AMJA TEMP. RANGE 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C -55C to +125C PIN-PACKAGE 8 Plastic DIP 8 SO Dice* 8 Plastic DIP 8 SO 8 CERDIP**
________________________Applications
+12V Flash Memory Programming Supplies Compact +12V Op-Amp Supplies Switching MOSFETs in Low-Voltage Systems Dual-Output +12V and +20V Supplies
* Dice are tested at TA = +25C. ** Contact factory for availability and processing to MIL-STD-883.
__________Typical Operating Circuit
INPUT 4.75V TO 5.5V
__________________Pin Configuration
TOP VIEW
4.7F VCC SHDN VOUT
OUTPUT 12V 5% 30mA
Vpp
C1- 1 C1+ 2 C2- 3 C2+ 4
8 7
SHDN GND VOUT VCC
MAX662A
0.22F C1+ C20.22F 4.7F
FLASH MEMORY
MAX662A
6 5
C1-
GND
C2+
DIP/SO
________________________________________________________________ Maxim Integrated Products
1
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+12V, 30mA Flash Memory Programming Supply MAX662A
ABSOLUTE MAXIMUM RATINGS
VCC to GND ................................................................-0.3V to 6V SHDN..........................................................-0.3V to (VCC + 0.3V) IOUT Continuous..................................................................50mA Continuous Power Dissipation (TA = +70C) Plastic DIP (derate 9.09mW/C above +70C) ............727mW SO (derate 5.88mW/C above +70C) .........................471mW CERDIP (derate 8.00mW/C above +70C) .................640mW Operating Temperature Ranges MAX662AC_A .....................................................0C to +70C MAX662AE_A ..................................................-40C to +85C MAX662AMJA................................................-55C to +125C 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
(Circuit of Figure 3a, VCC = 4.5V to 5.5V, TA = TMIN to TMAX, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS 0mA IOUT 30mA, VCC = 4.75V to 5.5V 0mA IOUT 20mA Output Voltage VOUT MAX662AM Supply Current Shutdown Current Oscillator Frequency Power Efficiency VCC-to-VOUT Switch Impedance Shutdown Input Threshold SHDN Pin Current ICC fOSC RSW VIH VIL VCC = 5V, VSHDN = 0V VCC = VSHDN = 5V 0mA IOUT 24mA, VCC = 4.75V to 5.5V 0mA IOUT 16mA No load, VSHDN = 0V No load, VSHDN = VCC VCC = 5V, IOUT = 30mA VCC = 5V, IOUT = 30mA MAX662AC/E VCC = VSHDN = 5V, IOUT = 30mA MAX662AM 2.4 -50 -15 0 0.4 -5 MIN 11.4 11.4 11.4 11.4 TYP 12 12 12 12 185 0.5 500 76 1 1 MAX 12.6 12.6 V 12.6 12.6 500 10 A A kHz % k V A UNITS
MAX662AC/E
2 2.5
__________________________________________Typical Operating Characteristics
(Circuit of Figure 3a, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX662A-01
OUTPUT VOLTAGE vs. OUTPUT CURRENT
MAX662A-02
EFFICIENCY vs. LOAD CURRENT
90 VCC = 5.5V 80 EFFICIENCY (%) 70 60 50 40 30 VCC = 4.5V VCC = 4.75V VCC = 5.0V CONTINUOUS OUTPUT CURRENT MUST NOT EXCEED 50mA ABS MAX LIMIT. INTERMITTENT PEAK CURRENTS MAY BE HIGHER. 0 10 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA)
MAX662A-03
300 280 SUPPLY CURRENT (A) 260 240 220 200 180 160 140 120 100 4.50 4.75 5.00 5.25 TA = +125C TA = 0C TA = +25C TA = -55C
12.6 12.4 12.2 OUTPUT VOLTAGE (V) 12.0 11.8 11.6 11.4 11.2 11.0 10.8 10.6
CONTINUOUS OUTPUT CURRENT MUST NOT EXCEED 50mA ABS MAX LIMIT. INTERMITTENT PEAK CURRENTS MAY BE HIGHER. VCC = 4.5V VCC = 4.75V VCC = 5.0V VCC = 5.5V
100
5.50
0
10 20 30 40 50 60 70 80 90 100 OUTPUT CURRENT (mA)
SUPPLY VOLTAGE (V)
2
_______________________________________________________________________________________
+12V, 30mA Flash Memory Programming Supply
_____________________________Typical Operating Characteristics (continued)
(Circuit of Figure 3a, TA = +25C, unless otherwise noted.) LOAD-TRANSIENT RESPONSE LINE-TRANSIENT RESPONSE
MAX662A
A A 0mA 0V
B
0V
B
1ms/div A: OUTPUT CURRENT, 20mA/div, IOUT = 0mA to 30mA B: OUTPUT VOLTAGE RIPPLE, 100mV/div, VCC = 5.0V
1ms/div A: SUPPLY VOLTAGE, 2V/div, VCC = 4.5V to 5.5V, IOUT = 30mA B: OUTPUT VOLTAGE RIPPLE, 200mV/div
_____________________Pin Description
PIN 1 2 3 4 5 6 7 NAME C1C1+ C2C2+ VCC VOUT GND FUNCTION Negative terminal for the first chargepump capacitor Positive terminal for the first chargepump capacitor Negative terminal for the second charge-pump capacitor Positive terminal for the second charge-pump capacitor Supply Voltage +12V Output Voltage. VOUT = VCC when in shutdown mode. Ground Active-high CMOS-logic level Shutdown Input. SHDN is internally pulled up to VCC. Connect to GND for normal operation. In shutdown mode, the charge pumps are turned off and VOUT = VCC.
VCC C4 4.7F VCC S1 S2 VOUT C2S1 ERROR AMP R1 C1+ 0.22F C1S1 OSCILLATOR S1 S2 S2 VREF SHDN R2
C2+ 0.22F
C3* 0.1F +12V C5 4.7F
MAX662A
8
SHDN
GND
SWITCH CLOSURES SHOWN FOR CHARGE PUMP IN THE TRANSFER MODE * C3 NOT REQUIRED. FOR MAX662 ONLY.
Figure 1. Block Diagram
_______________________________________________________________________________________ 3
+12V, 30mA Flash Memory Programming Supply MAX662A
_______________Detailed Description
Operating Principle
The MAX662A provides a regulated 12V output voltage at 30mA from a 5V 5% power supply, making it ideal for flash EEPROM programming applications. It uses internal charge pumps and external capacitors to generate +12V, eliminating inductors. Regulation is provided by a pulse-skipping scheme that monitors the output voltage level and turns on the charge pumps when the output voltage begins to droop. Figure 1 shows a simplified block diagram of the MAX662A. When the S1 switches are closed and the S2 switches are open, capacitors C1 and C2 are charged up to VCC. The S1 switches are then opened and the S2 switches are closed so that capacitors C1 and C2 are connected in series between V CC and VOUT. This performs a voltage tripling function. A pulseskipping feedback scheme adjusts the output voltage to 12V 5%. The efficiency of the MAX662A with VCC = 5V and I OUT = 30mA is typically 76%. See the Efficiency vs. Load Current graph in the Typical Operating Characteristics. During one oscillator cycle, energy is transferred from the charge-pump capacitors to the output filter capacitor and the load. The number of cycles within a given time frame increases as the load current increases or as the input supply voltage decreases. In the limiting case, the charge pumps operate continuously, and the oscillator frequency is nominally 500kHz.
Shutdown Mode
The MAX662A enters shutdown mode when SHDN is a logic high. SHDN is a TTL/CMOS-compatible input signal that is internally pulled up to V CC. In shutdown mode, the charge-pump switching action is halted and VIN is connected to VOUT through a 1k switch. When entering shutdown, VOUT declines to VCC in typically 13ms. Connect SHDN to ground for normal operation. When VCC = 5V, it takes typically 400s for the output to reach 12V after SHDN goes low (Figure 2).
__________Applications Information
Compatibility with MAX662
The MAX662A is a 100%-compatible upgrade of the MAX662. The MAX662A does not require capacitor C3, although its presence does not affect performance.
Capacitor Selection
Charge-Pump Capacitors, C1 and C2 The capacitance values of the charge-pump capacitors C1 and C2 are critical. Use ceramic or tantalum capacitors in the 0.22F to 1.0F range. For applications requiring operation over extended and/or military temperature ranges, use 1.0F tantalum capacitors for C1 and C2 (Figure 3b). Input and Output Capacitors, C4 and C5 The type of input bypass capacitor (C4) and output filter capacitor (C5) affects performance. Tantalums, ceramics or aluminum electrolytics are suggested. For smallest size, use Sprague 595D475X9016A7 surface-mount capacitors, which are 3.51mm x 1.81mm. For lowest ripple, use lowESR through-hole ceramic or tantalum capacitors. For lowest cost, use aluminum electrolytic or tantalum capacitors. Figure 3a shows the component values for proper operation over the commercial temperature range using minimum board space. The input bypass capacitor (C4) and output filter capacitor (C5) should both be at least 4.7F when using Sprague's miniature 595D series of tantalum chip capacitors. Figure 3b shows the suggested component values for applications over extended and/or military temperature ranges. The values of C4 and C5 can be reduced to 2F and 1F, respectively, when using ceramic capacitors. If using aluminum electrolytics, choose capacitance values of 10F or larger for C4 and C5. Note that as V CC increases above 5V and the output current decreases, the amount of ripple at VOUT increases due to the slower oscillator frequency combined with the higher input voltage. Increase the input and output bypass capacitance to reduce output ripple. Table 1 lists various capacitor suppliers.
5V 0V
SHDN
12V VOUT 5V
200s/div CIRCUIT OF FIGURE 3, VCC = 5V, IOUT = 200A
Figure 2. MAX662A Exiting Shutdown
4
_______________________________________________________________________________________
+12V, 30mA Flash Memory Programming Supply
Table 1. Capacitor Suppliers
Supplier Murata Erie Phone Number (814) 237-1431 Fax Number (814) 238-0490 RPE123Z5U105M50V Sprague Electric (603) 224-1961 (207) 324-4140 (603) 224-1430 (207) 324-7223 595D475X9016A7 595D105X9016A7 1.0F Ceramic (TH) 4.7F Tantalum (SM) 1.0F Tantalum (SM) Capacitor GRM42-6Z5U224M50 Capacitor Type* 0.22F Ceramic (SM)
MAX662A
*Note: (SM) denotes surface-mount component, (TH) denotes through-hole component.
Layout Considerations
2 C1 0.22F
3 C2 0.22F VIN 4.75V TO 5.5V VOUT +12V 5% AT 30mA C4 4.7F C5 4.7F
C2-
C1+
4 5
MAX662A
C2+ VCC C1SHDN
1 8
Layout is critical, due to the MAX662A's high oscillator frequency. Good layout ensures stability and helps maintain the output voltage under heavy loads. For best performance, use very short connections to the capacitors. The order of importance is: C4, C5, C1, C2.
Flash EEPROM Applications
PROGRAMMING CONTROL DIRECT FROM P
6
VOUT
GND
7
The circuit of Figure 3a is a +12V 5% 30mA flash EEPROM programming power supply. A microprocessor controls the programming voltage via the SHDN pin. When SHDN is low, the output voltage (which is connected to the flash memory VPP supply-voltage pin) rises to +12V to facilitate programming the flash memory. When SHDN is high, the output voltage is connected to VIN through an internal 1k resistor.
Figure 3a. Flash EEPROM Programming Power Supply for Commercial Temperature Range Applications
Paralleling Devices
Two MAX662As can be placed in parallel to increase output drive capability. The VCC, VOUT, and GND pins can be paralleled, reducing pin count. Use a single bypass capacitor and a single output filter capacitor with twice the capacitance value if the two devices can be placed close to each other. If the MAX662As cannot be placed close together, use separate bypass and output capacitors. The amount of output ripple observed will determine whether single input bypass and output filter capacitors can be used. Under certain conditions, one device may supply the total output current. Therefore, regardless of the number of devices in parallel, the maximum continuous current must not exceed 50mA.
3 *C2 1.0F VIN 4.75V TO 5.5V *C4 22F VOUT +12V 5% AT 30mA *C5 22F
C2-
C1+
2 *C1 1.0F
4 C2+ 5 VCC
MAX662A
C1SHDN
1 8
6
VOUT
GND
7
PROGRAMMING CONTROL DIRECT FROM P
12V and 20V Dual-Output Power Supply
*SPRAGUE 595D SERIES OR EQUIVALENT
Figure 3b. Flash EEPROM Programming Power Supply for Extended and/or Military Temperature Range Applications
Using the charge-pump voltage-doubler circuit of Figure 4, the MAX662A can produce a +20V supply from a single +5V supply. Figure 5 shows the current capability of the +20V supply.
_______________________________________________________________________________________
5
+12V, 30mA Flash Memory Programming Supply MAX662A
CIRCUIT OF FIGURE 4 VCC = 4.75V TA = +25C WITH +12V OUTPUT UNLOADED
MAX662AFIG 5
20.0 3 0.22F 4 C2+ C2C1+ 2 0.22F C1SHDN 12V OUTPUT 1N5818 1F 2F 16.0 0 GND 6 VOUT VCC 1 8 7 5 VIN = 5V 5% 20V OUTPUT VOLTAGE (V) 19.2
MAX662A
18.4
1F
17.6
WITH 34mA LOAD ON +12V OUTPUT
20V OUTPUT 1F
1N5818
16.8
5
10
15
20
25
30
35
40
20V OUTPUT CURRENT (mA)
Figure 4. +12V and +20V Dual Supply from a +5V Input
Figure 5. +20V Supply Output Current Capability
___________________Chip Topography
C2+ C2- C1+
0.086" (2.184mm) C1V CC SHDN
V OUT
0.086" (2.184mm)
GND
TRANSISTOR COUNT: 225 SUBSTRATE CONNECTED TO VOUT
6 _______________________________________________________________________________________

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