MICREL MIC2660BM5

MIC2660
Micrel
MIC2660
IttyBitty™ Charge Pump
Not Recommended for New Designs
General Description
Features
The MIC2660 IttyBitty™ 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.
• 3V input produces approx. 5V unregulated output*
3.8mA with 1µF 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
•
•
•
•
•
•
•
•
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 –40°C to +85°C ambient temperature range.
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
Temperature Range
Package
MIC2660BM5
–40°C to +85°C
SOT-23-5
Typical Application
+3V Input
0.01µF
MIC2660
1
5
3
IN
OUT
EN
GND
2
Enable
Disable
+5V, 2.5mA*
Output
0.01µF
* The output is unregulated and
follows a load-line type function
Low-Current Unregulated Step-Up Supply
Timing Diagram
2V
EN
0V
5V
0.2
µs
1.3
µs
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
Part
Identification
C10
4
5
NC
EN
SOT-23-5 (M5)
Pin Description
Pin Number
Pin Name
Pin Function
1
IN
2
GND
Ground: Power return.
3
OUT
Output: Charge pump output. Connect to load.
4
NC
Not internally connected.
5
EN
Enable (Input): CMOS compatible input. EN high (VEN = VIN) enables the
charge pump . EN low (VIN = 0V) disables the charge pump.
Supply (Input): +3V to +5V supply.
Absolute Maximum Ratings
Input Voltage (VIN) ..................................................... +5.5V
Enable Voltage (VEN) ......................................... VIN + 1.3V
Ambient Temperature Range (TA) ............. –40°C to +85°C
Lead Temperature, Soldering 10sec. ........................ 300°C
Package Thermal Resistance
SOT-23-5 θJA .................................................... 220°C/W
SOT-23-5 θJC .................................................... 130°C/W
Electrical Characteristics
Parameter
Condition (Note 1)
Min
Typ
Output Voltage, Enabled
VIN = 3V, VEN = VIN, COUT = 1000pF, RL = 2kΩ
4.5
5
V
VIN = 5V, VEN = VIN, COUT = 1000pF, RL = 2kΩ
8.1
9
V
VIN = 3V, VEN = GND, COUT = 1000pF, RL = 2kΩ
.9
1.0
1.3
V
VIN = 5V, VEN = GND, COUT = 1000pF, RL = 2kΩ
2.9
3.0
3.3
V
VIN = 3V, VEN = VIN, RL = 2kΩ
14.5
19.5
mA
VIN = 5V, VEN = VIN, RL = 2kΩ
28.5
38.5
mA
Output Voltage, Disabled
Input Current
Quiescent Current
Output Current
Enable Threshold
Max
Units
VIN = 3V, VEN < 0.4V
1.5
3
µA
VIN = 5V, VEN < 0.4V
3.5
5
µA
VIN = 3V, VEN = VIN, VOUT = VOUT min
1.9
2.5
mA
VIN = 5V, VEN = VIN, VOUT = VOUT min
3.4
4.5
mA
VIN = 3V
1.5
V
VIN = 5V
2.5
V
10
µA
Enable Current
VIN = 5V, VEN = VIN
Turn-On Time
VIN = 3V
Load = 2kΩ, COUT = 1000pF, Note 2
200
ns
Turn-Off Time
VIN = 3V
Load = 2kΩ, COUT = 1000pF, Note 3
1.3
µs
General Note: Devices are ESD protected, however handling precautions are recommended.
Note 1:
Typicals values at TA = 25°C. Minimum and maximum values at –40°C ≤ TA ≤ +85°C.
Note 2:
Turn-on time is the time between VEN = 0.5 × VIN and VOUT = 0.9 (VOUTmax – VOUTmin) for a rising EN input.
Note 3:
Turn-off time is the time between VEN = 0.5 × VIN and VOUT = VIN – 1.9V for a falling EN input.
MIC2660
2
August 1999
MIC2660
Micrel
Typical Characteristics
Output Voltage
vs. Supply Voltage
Output Voltage
vs. Supply Voltage
20
15
NO LOAD
10
3mA
2mA
5
1mA
0
2.0
2.5 3.0 3.5 4.0 4.5
SUPPLY VOLTAGE (V)
20
COUT = NONE
TA = 25° C
15
NO LOAD
10
3mA
2mA
5
1mA
0
2.0
5.0
Output Voltage
vs. Supply Voltage
2.5 3.0 3.5 4.0 4.5
SUPPLY VOLTAGE (V)
10
3mA
2mA
1mA
0
2.0
2.5 3.0 3.5 4.0 4.5
SUPPLY VOLTAGE (V)
10
3mA
5
2mA
1mA
15
NO LOAD
10
3mA
5
2mA
1mA
Efficiency
vs. Output Voltage
2.5 3.0 3.5 4.0 4.5
SUPPLY VOLTAGE (V)
COUT = 1µF
TA = 125° C
15
NO LOAD
10
3mA
5
2mA
1mA
0
2.0
5.0
Efficiency
vs. Output Voltage
35
35
30
30
2.5 3.0 3.5 4.0 4.5
SUPPLY VOLTAGE (V)
35
30
2mA
15
10
0
25
20
2mA
15
1mA
10
COUT = NONE
TA = 25° C
5
3mA
2
4
6
8 10 12
OUTPUT VOLTAGE (V)
0
14
0
Efficiency
vs. Output Voltage
2mA
15
COUT = 1µF
TA = -55° C
0
August 1999
1mA
2
4
6
8 10 12
OUTPUT VOLTAGE (V)
EFFICIENCY (%)
EFFICIENCY (%)
25
5
15
1mA
10
0
14
COUT = NONE
TA = 125° C
0
35
3mA
30
25
2mA
20
15
1mA
10
0
14
Efficiency
vs. Output Voltage
COUT = 1µF
5 T = 25° C
A
14
2
4
6
8 10 12
OUTPUT VOLTAGE (V)
40
35
3mA
10
2mA
20
Efficiency
vs. Output Voltage
30
0
2
4
6
8 10 12
OUTPUT VOLTAGE (V)
40
35
20
25
5
0
EFFICIENCY (%)
0
1mA
COUT = NONE
TA = -55° C
5
EFFICIENCY (%)
EFFICIENCY (%)
EFFICIENCY (%)
3mA
20
5.0
Efficiency
vs. Output Voltage
3mA
25
5.0
20
COUT = 1µF
TA = 25° C
0
2.0
5.0
2.5 3.0 3.5 4.0 4.5
SUPPLY VOLTAGE (V)
Output Voltage
vs. Supply Voltage
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
NO LOAD
5
NO LOAD
0
2.0
5.0
20
COUT = 1µF
TA = -55° C
15
COUT = NONE
TA = 125° C
15
Output Voltage
vs. Supply Voltage
20
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
COUT = NONE
TA = -55° C
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
20
Output Voltage
vs. Supply Voltage
3mA
30
25
2mA
20
15
1mA
10
COUT = NONE
TA = 125° C
5
2
4
6
8 10 12
OUTPUT VOLTAGE (V)
3
14
0
0
2
4
6
8 10 12
OUTPUT VOLTAGE (V)
14
MIC2660
MIC2660
Micrel
Block Diagram
IN MIC2660
2×
D1
3×
D2
Q1
EN
OSC
OUT
D3
Q3
XLO
C1
Q2
XLO
Q4
C2
GND
Functional Description
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 “2×” and “3×” nodes,
V2× and V3×, increases.
Q2 turns on, completing the ground path to charge C1 (and
the 2× node) to the supply voltage, less a diode voltage drop.
V2× (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 2× node,
that was nominally at the supply voltage, becomes nominally
twice the supply voltage.
V2× = VIN – VD1 + VIN
While Q1 is on, Q4 is also on. When Q4 is on, the nominally
doubled voltage at the 2× node is applied across C2, through
D2.
V3× (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 3× node, that was nominally twice the supply voltage, becomes nominally three
times the supply voltage.
V3× = 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.
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
MIC2660
4
August 1999
MIC2660
Micrel
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 1000µF Capacitor can be
charged from 2V to approximately 12V in less than 3 seconds
by a 5V powered MIC2660. (i = C dv/dt).
Applications Information
Electromagnetic Interference
The 18MHz oscillator may cause interference to radio circuits. 0.01µF 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.
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 68Ω resistor in series
with the output limits short-circuit current to 30mA.
+5V
MIC2660
1
100k
5
Load
Supply
+3V to +5V
100k
5
Enable
Disable
IN
EN
OUT
EN
GND
3
68Ω
2
+12V
1000µF
0.1µF
RLOAD
MIC2660
1
IN
OUT
GND
3
Figure 2. Charge-Pump/Dump
2
5-Volt Lamp Flasher
1µF
0.1µF
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||RT×CT,while RT and CT set the “off” time to 1.1RT×CT.
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
RT1MΩ
MIC1557
CT
0.68µF
4
VS
1
T/T
2
GND
CS
OUT
5V lamp
3
5
MIC2660
1
IN
OUT
3
5
EN
GND
2
IRL3103
N-channel
FET
0.1µF
2k
Figure 3. 5-Volt Lamp Flasher
August 1999
5
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)
0.50 (0.020)
0.35 (0.014)
1.30 (0.051)
0.90 (0.035)
0.20 (0.008)
0.09 (0.004)
10°
0°
0.15 (0.006)
0.00 (0.000)
0.60 (0.024)
0.10 (0.004)
SOT-23-5 (M5)
MIC2660
6
August 1999
MIC2660
August 1999
Micrel
7
MIC2660
MIC2660
Micrel
MICREL INC.
TEL
1849 FORTUNE DRIVE SAN JOSE, CA 95131
+ 1 (408) 944-0800
FAX
+ 1 (408) 944-0970
WEB
USA
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.
© 1999 Micrel Incorporated
MIC2660
8
August 1999