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MIC2660
Micrel
MIC2660
IttyBittyTM Charge Pump Not Recommended for New Designs
General Description
The MIC2660 IttyBittyTM charge pump functions as a lowcurrent, step-up converter where conventional inductor based, dc-to-dc converters are too complex and expensive. This device features a complete, self-contained charge pump in a tiny 5-lead SOT-23-5 package. The MIC2660 is powered from a 3V to 5V nominal supply and produces nominally 5V to 9V as a function of the input voltage. The output is unregulated and follows a load-line type function. The MIC2660 can be used with or without external components. When used with two noncritical external capacitors, a 3V input will produce 5V at 3.8mA. With no external components, a 3V input will produce 5V at 2.5mA. The MIC2660 charge pump consists of an approximately 18MHz oscillator and a voltage tripler. The MIC2660 is available in the SOT-23-5 package and is rated for -40C to +85C ambient temperature range.
Features
* 3V input produces approx. 5V unregulated output* 3.8mA with 1F external output capacitor 2.5mA without external capacitor * 5V input produces approx. 9V unregulated output* 4.5mA output without external capacitor * CMOS-logic compatible enable * ESD protected
Applications
* * * * * * * * Squib firing Refresh Burst/dump Low duty cycle load LCD bias generator Local 5V logic supply MOSFET driver Battery or solarcell boost
Ordering Information
Part Number MIC2660BM5 Temperature Range -40C to +85C Package SOT-23-5
Typical Application
+3V Input 0.01F MIC2660
1 3
IN EN
OUT GND
2
5
+5V, 2.5mA* Output 0.01F * The output is unregulated and follows a load-line type function
Enable Disable
Low-Current Unregulated Step-Up Supply
Timing Diagram
2V
EN
0V
5V
0.2 s
1.3 s
OUT
1V 0V
Output vs. Enable Input
Micrel, Inc. * 1849 Fortune Drive * San Jose, CA 95131 * USA * tel + 1 (408) 944-0800 * fax + 1 (408) 944-0970 * http://www.micrel.com
August 1999
1
MIC2660
MIC2660
Micrel
Pin Configuration
OUT GND IN
3 2 1
C10
4 5
Part Identification
NC
EN
SOT-23-5 (M5)
Pin Description
Pin Number 1 2 3 4 5 Pin Name IN GND OUT NC EN Pin Function Supply (Input): +3V to +5V supply. Ground: Power return. Output: Charge pump output. Connect to load. Not internally connected. Enable (Input): CMOS compatible input. EN high (VEN = VIN) enables the charge pump . EN low (VIN = 0V) disables the charge pump.
Absolute Maximum Ratings
Input Voltage (VIN) ..................................................... +5.5V Enable Voltage (VEN) ......................................... VIN + 1.3V Ambient Temperature Range (TA) ............. -40C to +85C Lead Temperature, Soldering 10sec. ........................ 300C Package Thermal Resistance SOT-23-5 JA .................................................... 220C/W SOT-23-5 JC .................................................... 130C/W
Electrical Characteristics
Parameter Output Voltage, Enabled Condition (Note 1) VIN = 3V, VEN = VIN, COUT = 1000pF, RL = 2k VIN = 5V, VEN = VIN, COUT = 1000pF, RL = 2k Output Voltage, Disabled VIN = 3V, VEN = GND, COUT = 1000pF, RL = 2k VIN = 5V, VEN = GND, COUT = 1000pF, RL = 2k Input Current VIN = 3V, VEN = VIN, RL = 2k VIN = 5V, VEN = VIN, RL = 2k Quiescent Current VIN = 3V, VEN < 0.4V VIN = 5V, VEN < 0.4V Output Current VIN = 3V, VEN = VIN, VOUT = VOUT min VIN = 5V, VEN = VIN, VOUT = VOUT min Enable Threshold VIN = 3V VIN = 5V Enable Current Turn-On Time Turn-Off Time VIN = 5V, VEN = VIN VIN = 3V VIN = 3V Load = 2k, COUT = 1000pF, Note 2 Load = 2k, COUT = 1000pF, Note 3 200 1.3 1.5 3.5 1.9 3.4 2.5 4.5 1.5 2.5 10 Min 4.5 8.1 .9 2.9 Typ 5 9 1.0 3.0 14.5 28.5 1.3 3.3 19.5 38.5 3 5 Max Units V V V V mA mA A A mA mA V V A ns s
General Note: Devices are ESD protected, however handling precautions are recommended. Note 1: Note 2: Note 3: Typicals values at TA = 25C. Minimum and maximum values at -40C TA +85C. Turn-on time is the time between VEN = 0.5 x VIN and VOUT = 0.9 (VOUTmax - VOUTmin) for a rising EN input. Turn-off time is the time between VEN = 0.5 x VIN and VOUT = VIN - 1.9V for a falling EN input.
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Typical Characteristics
Output Voltage vs. Supply Voltage
20 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) COUT = NONE TA = -55 C NO LOAD 10 3mA 5 1mA 0 2.0 2.5 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 5.0 2mA 20 OUTPUT VOLTAGE (V) COUT = NONE TA = 25 C NO LOAD 10 3mA 5 1mA 0 2.0 2.5 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 5.0 2mA
Output Voltage vs. Supply Voltage
20
Output Voltage vs. Supply Voltage
COUT = NONE TA = 125 C NO LOAD 10 3mA 5 1mA 0 2.0 2.5 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 5.0 2mA
15
15
15
Output Voltage vs. Supply Voltage
20 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) COUT = 1F TA = -55 C NO LOAD 10 3mA 5 1mA 0 2.0 2.5 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 5.0 2mA 20
Output Voltage vs. Supply Voltage
20 OUTPUT VOLTAGE (V) COUT = 1F TA = 25 C NO LOAD 10 3mA 5 1mA 0 2.0 2.5 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 5.0 2mA
Output Voltage vs. Supply Voltage
COUT = 1F TA = 125 C NO LOAD 10 3mA 5 1mA 0 2.0 2.5 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 5.0 2mA
15
15
15
Efficiency vs. Output Voltage
35 30 EFFICIENCY (%) EFFICIENCY (%) 25 20 15 10 5 0 0 COUT = NONE TA = -55 C 2mA 1mA 3mA 35 30
Efficiency vs. Output Voltage
35 30 3mA 25 20 15 10 5 14 0 0 COUT = NONE TA = 25 C 2 4 6 8 10 12 OUTPUT VOLTAGE (V) 14 1mA 2mA EFFICIENCY (%) 25 20 15
Efficiency vs. Output Voltage
3mA
2mA
1mA 10 5 0 0 COUT = NONE TA = 125 C 2 4 6 8 10 12 OUTPUT VOLTAGE (V) 14
2 4 6 8 10 12 OUTPUT VOLTAGE (V)
Efficiency vs. Output Voltage
35 30 EFFICIENCY (%) EFFICIENCY (%) 3mA 25 20 15 10 5 0 0 COUT = 1F TA = -55 C 1mA 2mA 40 35
Efficiency vs. Output Voltage
40 35 EFFICIENCY (%) 3mA 30 25 20 15 10 5 14 0 0
Efficiency vs. Output Voltage
3mA
30 25 20 15 10 COUT = 1F 5 T = 25 C A 0 0 1mA
2mA 1mA COUT = NONE TA = 125 C 2 4 6 8 10 12 OUTPUT VOLTAGE (V) 14
2mA
2 4 6 8 10 12 OUTPUT VOLTAGE (V)
14
2 4 6 8 10 12 OUTPUT VOLTAGE (V)
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MIC2660
MIC2660
Micrel
Block Diagram
IN MIC2660 D1 2x D2 Q1 EN OSC XLO Q2 C1 XLO Q4 Q3 C2 3x D3 OUT
GND
Functional Description
Refer to the block diagram. The MIC2660 charge pump consists of an oscillator and a voltage tripler. A logic-high applied to EN activates the charge pump. The charge pump produces an output voltage that is higher than the input voltage. Supply Input IN (supply input) is rated for +2.7V to +5.5V. Ouput OUT is connected to IN, less 3 diode drops, at all times. Enable EN (enable) is a CMOS input. A logic low turns the oscillator off. The threshold is approximately half the supply voltage. A floating EN input may cause unpredictable operation. Oscillator The oscillator produces a square wave at approximately 18MHz. It has a noninverting and an inverting output. Crossover Lockout The charge pump contains two crossover lockout (XLO) circuits. Each crossover lockout circuit drives a totem pole, consisting of a P-channel MOSFET and an N-channel MOSFET. The crossover lockout alternately switches the MOSFETs with no significant transition current (shoot-through current from supply to ground). Tripler Voltage stepup is performed by charging an internal capacitor then switching the charged capacitor in series with the supply voltage to produce a higher voltage. A description of the nominal voltage tripler output is: VOUT = 3VIN - 3VD. where: VOUT = output voltage VIN = supply voltage VD = voltage drop across forward biased diode
All formulas are simplified. Refer to the last paragraph of this subsection about the actual output voltage. The following sequence describes the basic operation of the tripler by showing how the voltage at the "2x" and "3x" nodes, V2x and V3x, increases. Q2 turns on, completing the ground path to charge C1 (and the 2x node) to the supply voltage, less a diode voltage drop. V2x (charging) = VIN - VD1 After Q2 turns off, Q1 turns on. The Q1-Q2 side of C1 is switched (offset upward) from ground to VIN. The 2x node, that was nominally at the supply voltage, becomes nominally twice the supply voltage. V2x = VIN - VD1 + VIN While Q1 is on, Q4 is also on. When Q4 is on, the nominally doubled voltage at the 2x node is applied across C2, through D2. V3x (charging) = VIN - VD1 + VIN - VD2 After Q4 turns off, Q3 turns on. The Q3-Q4 side of C2 is switched from ground to VIN. The 3x node, that was nominally twice the supply voltage, becomes nominally three times the supply voltage. V3x = VIN - VD1 + VIN - VD2 + VIN The tripled voltage is available at the output through D3. VOUT = VIN - VD1 + VIN - VD2 + VIN - VD3 The output is nominally 3 times the supply voltage less the voltage drop across three diodes. The actual output is lower. These simplified formulas do not show that the voltage across the capacitors decreases when charge flows to the following stage or output. An actual device also has some internal loss. ESD Protection Zener diodes are provided at IN, EN, and OUT to limit ESD voltage.
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MIC2660
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Charge-Pump/Dump A large capacitor can be charged to the unloaded tripled voltage output after a time based on the maximum current provided by the MIC2660. A 1000F Capacitor can be charged from 2V to approximately 12V in less than 3 seconds by a 5V powered MIC2660. (i = C dv/dt). Once charged, a maximum current of 3mA may be drawn continuously at the 12V level. A high value bleeder resistor (100k) is not needed to prevent spikes from exceeding the capacitor voltage rating, since the MIC2660's internal 15V ESD zener limits maximum output. A 68 resistor in series with the output limits short-circuit current to 30mA.
+5V
Applications Information
Electromagnetic Interference The 18MHz oscillator may cause interference to radio circuits. 0.01F bypass capacitors should be mounted close to the IN and OUT terminals. Low-Side MOSFET Charge-Pump Driver A standard MOSFET requires approximately 15V to fully enhance the gate for minimum RDS(on). Substituting a logiclevel MOSFET reduces the required gate voltage, allowing an MIC2660 to be used as an low-side FET driver. A 3V powered MIC2660 will fully enhance a logic-level N-channel MOSFET low-side switch, with a 5k gate pulldown resistor, in less than 1ms after the enable pin rises above 1.5V. The 1nF MOSFET gate capacitance will be discharged to turn-off in less than 10ms after the enable pin goes below 1.5V.
+3V to +5V Load Supply RLOAD
3
MIC2660 100k
1
IN EN
OUT GND
3
68
5
2
+12V 1000F
0.1F
MIC2660 100k
Enable Disable 1
IN EN
OUT GND
Figure 2. Charge-Pump/Dump
1F
5
2
5-Volt Lamp Flasher An IttyBitty MIC1557 oscillator provides a short pulse once per second, enabling the CS pin of an MIC2660, which charges the gate-to-drain capacitance of a logic-level N-channel MOSFET to approximately 9V, which turns on a lamp. When the CS pin is low, a 2k resistor discharges the gate capacitance, turning off the lamp. A resistor (RS) in series with a diode determines the "on" time to approximately RS||RTxCT,while RT and CT set the "off" time to 1.1RTxCT.
0.1F
Figure 1. Charge-Pump Driver An MIC2660 boosts a 5V input to 9V-12V to fully enhance an N-channel MOSFET, which may have its drain connected to a higher voltage, through a high-side load. A TTL high signal applied to CS enables the internal oscillator, which quickly develops 9V-12V at the gate of the MOSFET, clamped by a zener diode. A resistor from the gate to ground ensures that the FET will turn off quickly when the MIC2660 is turned off.
+5V RS 470k RT1M
MIC1557
4 1
VS T/T GND
CS
3 1
5V lamp MIC2660 IN EN OUT GND
3
CT 0.68F
2
OUT
5
5
2
IRL3103 N-channel FET 2k
0.1F
Figure 3. 5-Volt Lamp Flasher
August 1999
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MIC2660
MIC2660
Micrel
Package Information
1.90 (0.075) REF 0.95 (0.037) REF
1.75 (0.069) 1.50 (0.059)
3.00 (0.118) 2.60 (0.102)
DIMENSIONS: MM (INCH) 3.02 (0.119) 2.80 (0.110) 1.30 (0.051) 0.90 (0.035) 10 0 0.15 (0.006) 0.00 (0.000) 0.20 (0.008) 0.09 (0.004)
0.50 (0.020) 0.35 (0.014)
0.60 (0.024) 0.10 (0.004)
SOT-23-5 (M5)
MIC2660
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August 1999
MIC2660
Micrel
August 1999
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MIC2660
MIC2660
Micrel
MICREL INC.
TEL
1849 FORTUNE DRIVE SAN JOSE, CA 95131
FAX
USA
+ 1 (408) 944-0800
+ 1 (408) 944-0970
WEB
http://www.micrel.com
This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc. (c) 1999 Micrel Incorporated
MIC2660
8
August 1999

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