ZXCP330 [ZETEX]
SWITCHED CAPACITOR DC-DC CONVERTER; 开关电容DC-DC转换器
| 型号： | ZXCP330 |
| 厂家： | 
ZETEX SEMICONDUCTORS |
| 描述： | SWITCHED CAPACITOR DC-DC CONVERTER |
| 文件： | 总9页 (文件大小：344K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
ZXCP330
SWITCHED CAPACITOR DC-DC CONVERTER
DEVICE DESCRIPTION
The ZXCP330 is the first in a series of switched capacitor DC to DC converters,
converting an input voltage from between 2 volts and 4.4 volts to a regulated
output voltage of 3.3V with a maximum load current of 40mA. The device
operates with one flying capacitor and two small bypass capacitors at input
and output making for a very small solution. Very low quiescent current
makesthesedevicesidealforlowpowerandbatterypoweredapplications.
Regulation is achieved by sensing the output and enabling the device charge pump when it falls below the sense
threshold. This technique leads to high efficiency conversion. The method is also efficient for low current loads.
Herethedutycyclewillbelowandthequiescentcurrentdrawnwhilstthechargepumpisdisabledisverysmall.
The device includes a pin for logic controlled shutdown of the output, and also features thermal shutdown, which
protects against short circuit damage as well as excessive temperatures. The device is supplied in a 6 lead SOT-23
package.
Contact Zetex marketing for availability of other voltage options.
FEATURES
APPLICATIONS
· Very low power: IQ = 20µA
· Battery backup supplies
· Regulated output voltage: 3.3V, 4ꢀ
· Output current: 20mA at VIN = 2V
· Output current: 40mA at VIN = 2.5V
· No inductors required
· Smart card readers
· Li-Ion battery backup supplies
· SIM interface supplies for cellular phones
· Hand held computers
· Very low shutdown current: <1µA
· Short circuit and over-temp protected
· Very small package: SOT23-6 pin
APPLICATIONS DIAGRAM
PROVISIONAL ISSUE A - DECEMBER 2001
1
ZXCP330
ABSOLUTE MAXIMUM RATINGS
VIN to GND
-0.3V to +7V
Operating Temperature
-40°C to 85°C
-55°C to 125°C
Thermally ltd
EN to ground
-0.3V to +7V
-0.3V to +5.5V
150mA
Storage Temperature Range
Continuous Power Dissipation
V
OUT to ground
IOUT
ELECTRICAL CHARACTERISTICS
TEST CONDITIONS (unless otherwise stated): TA=-40°C to 85°C, (typical values at 25°), EN = VIN, CFLY=0.22F,
CIN=10F, COUT=10F
PARAMETER
SYMBOL CONDITIONS
MIN
TYP
MAX UNIT
Input Voltage
VIN
2.0
4.4
V
V
Output Voltage
Note 1
VOUT
2VՅVINՅ 4.4V, IOUTՅ20mA
3.17
3.3
3.3
3.43
3.43
2.5VՅVINՅ4.4V, IOUTՅ40mA 3.17
Maximum Output Current
IO(max)
VIN Ն 2V
20
40
mA
VIN Ն 2.5V
Output Short-Circuit Current
Supply Current
ISC
VIN = 2V
125
20
mA
A
ꢀ
IQ
2VՅ VINՅ 4.4V , No load
VIN=2V, IOUT = 20mA
Oscillator free running
40
Efficiency
82
Switching Frequency
Line Regulation (Note 2)
fOSC
⌬VLDR
500
0
kHz
mV
VIN=2.5V to 4.4V, IOUT=40mA, -50
TA=25°C
50
50
Load Regulation (Note 2)
Output Voltage Ripple
⌬VLDR
VR
VEN(ON)
VEN(OFF
IOUT=1mA to 40mA, VIN=2.5V -50
TA=25°C
0
mV
f=500kHz, VIN=2.5V,
IOUT = 40mA
20
mV pk-pk
Enable pin Input Threshold
High
Device active
1.5
0
5.5
0.3
V
V
Enable pin Input Threshold
Low
)
Device shutdown
TA=25°C, EN = 4.4V
Enable pin Input current
Shutdown supply Current
IEN
100
1
nA
IQ(SD)
EN=0V, 2V Յ VIN Յ 4.4V,
TA=25°C
A
Shutdown time (Note 3)
VOUT Turn-on Time
TSD
VIN = 2.5V, EN changes from
1.5V to 0.3V
20
s
TON
TSD
VIN=2V, IOUT = 0mA
500
150
s
Thermal Shutdown
Temperature
135
165
°C
Note 1: Contact Zetex marketing for availability of alternative output voltages
Note 2: Output can deviate EITHER side of Vnominal for increased load current or line voltage
Note 3: Shutdown time is the time taken for IIN to reduce to <1A
PROVISIONAL ISSUE A - DECEMBER 2001
2
ZXCP330
TYPICAL CHARACTERISTICS
PROVISIONAL ISSUE A - DECEMBER 2001
3
ZXCP330
Load transient response
Start-up time
Channel 1: VOUT @20mV/DIV
Channel 3: IOUT @10mA/DIV
Channel 1: VOUT @1V/DIV
Channel 2: EN @2V/DIV
V
IN=4.4V; IOUT=40mA; Time base=50s/DIV
V
IN=4.4V; IOUT=0mA to 25mA; Time base=200s/DIV
Output ripple
Channel 1: VOUT @20mV/DIV
V
IN=2.5V; IOUT=40mA; Time base=2s/DIV
PROVISIONAL ISSUE A - DECEMBER 2001
4
ZXCP330
Block Diagram
Power efficiency
The ZXCP330 is essentially a regulated voltage
doubling charge pump. As for all voltage doubling
charge pumps the input current is always twice the
output current. The efficiency equation for an ideal
voltage doubler is given below:
P
P
OUT
V
OUT × IOUT
V
2VIN
OUT
=
=
=
IN
2IOUT × VIN
The ZXCP330 maintains good efficiency at light loads
because of its inherently low power design. At higher
loads switching losses are minimal so efficiency is
close to the ideal. See Efficiency vs Output current
graph in the typical characteristics section.
Short circuit/thermal protection
When the output of the ZXCP330 is short circuited, the
resultant current depends on 2 factors. At low input
voltages, the internal resistance of the switches limits
the current and so it will increase with input voltage.
However since, under this condition, all the input
power is dissipated in the chip, it will self-heat. When
the input voltage reaches around 3.2V, the value
depending on the thermal mounting of the device, the
chip temperature reaches a nominal value of 150ЊC and
a thermal shutdown circuit inhibits the switching. The
device will then cool and the thermal shutdown will
re-enable the switching. It will cycle in and out of
operation indefinitely until the short circuit is removed.
Since the thermal shutdown circuit is then maintaining
constant die temperature, it becomes a “constant
power sink”, so an increase in the input voltage results
in the on time becoming proportionately less so the
current decreases to maintain constant power.
Operational description
The ZXCP330 uses a standard switched capacitor
voltage doubler topology to generate a regulated
output of 3.3V from an input voltage of between 2V and
4.4V. A 500kHz internal clock generates two phases.
During 1 (Phi One) the flying capacitor is connected
between Vin and ground for 1s. During 2 the bottom
plate is connected to VIN and the top plate connected to
V
OUT. A proportion of the output voltage is compared
with a silicon band gap to maintain regulation. This is
achieved by disabling the switching operation when
the output voltage is above 3.3V and re-enabling when
the output voltage falls below 3.3V. When the input
voltage is near the higher limit, a large amount of
charge is acquired by the flying capacitor during 1,
which would result in excessive output ripple. For this
reason, the 2 phase is cut short if the voltage exceeds
3.3V, so that the full charge on the flying capacitor is
not delivered to the output capacitor, hence ripple is
reduced.
Capacitor selection
Output capacitors are a critical choice in the overall
performance of the solution. Output voltage ripple,
converter output power and turn-on time are
influenced by the choice of capacitor. To reduce noise
and output voltage ripple multi layer ceramic
capacitors are recommended for use at the ZXCP330
input and output because of their inherently low ESR,
typically <0.1⍀.
When the charge pump is disabled, the current drawn
by the switches themselves is <1A. This means that at
zero loads, the load on the output will only consist of
the divider driving the output comparator and the band
gap circuit, resulting the device cycling very slowly and
drawing only 20A.
The ZXCP330 will function satisfactorily over a wide
range of capacitor values and load currents. However,
to achieve maximum output current and minimum
output ripple it is important to choose the values
carefully. Available output current increases with the
value of the flying capacitor, with input voltage and
with clock frequency (which is fixed internally). Ripple
increases with input voltage and the ratio of the flying
capacitor to the output capacitor.
When the circuit is either waiting for the next cycle or
when it is shutdown by taking the ENABLE pin low, it
remains in the 1 state so that the flying capacitor stays
charged to the input voltage ready for 2 to be enabled
immediately. During shutdown all analogue circuits
areswitchedoff, resultinginacurrentdrainof<100nA.
PROVISIONAL ISSUE A - DECEMBER 2001
5
ZXCP330
Capacitor selection
Layout considerations
An absolute minimum value of 220nF for the flying Careful layout of the ZXCP330 application circuit is
capacitor is needed to obtain maximum output current essential for correct operation because of its high
and 330nF is probably safer with tolerance in mind. switching frequency and transient currents. For
However much lower capacitors can be used if the optimum converter performance use a ground plane
device is being used at light loads. An output capacitor and keep PCB tracks to all capacitors short to minimise
of 10F is recommended and this should be as low an output voltage ripple and maintain regulation under all
ESR as possible as the output consists of large current conditions.
spikes, so ceramics are preferred. Because the flying
The recommended layout configuration is shown
capacitor charges from the input via a switch, inrush below:
current is also large and a low ESR capacitor should be
used for input decoupling.
The device senses the output voltage in order to
regulate at 3.3V and any inductance in series with
either end of the output capacitor will cause ringing
which will not be damped as the output capacitor has
low ESR. This is very undesirable from a regulation or
ripple aspect, therefore short connections must be
used between device pins and all capacitors (see
Layout Considerations later) to keep the waveforms as
clean as possible.
The dielectric of the ceramic capacitor is an important
consideration for the ZXCP330 operation over
temperature. Zetex recommends minimum dielectric
Image enlarged to show detail.
specification of X7R for the flying capacitor and X5R for
the input and output capacitors. Capacitors used with a
lower specification dielectric can cause excessive
noise and output voltage ripple and can also
compromise output current over temperature. For
example a ceramic capacitor with an X7R dielectric will
lose 20ꢀ of its capacitance over a -40ЊC to 85ЊC
temperature range, whereas a capacitor with a Y5V
dielectric loses 80ꢀ of its capacitance at -40ЊC and 75ꢀ
at 85ЊC.
Actual size (8mmx5.3mm)
Thermal management
At high input voltages and load currents the ZXCP330
power dissipation is high. As mentioned previously,
the ZXCP330 will shutdown when the junction
temperature of the device reaches 150ЊC. To reduce the
junction temperature of the device a good thermal
connection to the PCB is necessary. This can be
achieved by connecting the GND pin of the ZXCP330 to
a solid ground plane running on the second layer of a 2
layer PCB, adding extra heatsinking.
PROVISIONAL ISSUE A - DECEMBER 2001
6
ZXCP330
TYPICAL APPLICATIONS
Low quiescent current, regulated operation
Low noise 3V supply
By adding the ZXCL300 3V regulator to the output of
the ZXCP330, the output voltage ripple can be
eliminated.
By pulsing the enable pin (pin 3) lower quiescent
operating current can be achieved while maintaining
output voltage regulation. A pulse frequency of 100Hz
with a 2ꢀ duty cycle is a suitable to achieve a 10A
operating current.
A typical waveform of the reduction in noise is shown
below.
LED driver
Below is a typical LED driving application for a cell
phone. The ZXCP330 drives a coloured LED with a
typical forward voltage of 2.5V from a single Li-on
battery input. The LEDs can be driven in parallel to
provide backlighting for LCD displays and keypad
illumination. The LED current is regulated by R1 and is
configured for 20mA.
Channel 1: VOUT ZXCP330 @20mV/DIV
Channel 2: VOUT ZXCL300 @20mV/DIV
V
IN=4.4V; IOUT=40mA; Time base=2s/DIV
PROVISIONAL ISSUE A - DECEMBER 2001
7
ZXCP330
PINOUT DIAGRAM
Top View
PINOUT TABLE
Device Pin
Pin description
Output voltage
Ground
Pin description
1
2
3
4
VOUT
GND
EN
Enable
Flying capacitor
negative pin
CFLY-
5
6
Input voltage
VIN
Flying capacitor
positive pin
CFLY+
ORDERING INFORMATION
Device
Output voltage (V)
3.3
Part marking
ZXCP330E6
P330
PROVISIONAL ISSUE A - DECEMBER 2001
8
ZXCP330
PACKAGE DIMENSIONS
PAD LAYOUT DETAILS
e
b
2
L
E1
E
DATUM A
a
e1
D
A
A2
A1
DIM
Millimetres
Min
Inches
Max
1.45
0.15
1.30
0.50
0.20
3.00
3.00
1.75
0.60
Min
0.35
Max
A
A1
A2
b
0.90
0.00
0.90
0.35
0.09
2.80
2.60
1.50
0.10
0.057
0.006
0.051
0.019
0.008
0.118
0.118
0.069
0.002
0
0.035
0.014
0.0035
0.110
0.102
0.059
0.004
C
D
E
E1
L
e
0.95 REF
1.90 REF
10°
0.037 REF
0.074 REF
0° 10°
e1
L
0°
© Zetex plc 2001
Zetex plc
Fields New Road
Chadderton
Oldham, OL9 8NP
United Kingdom
Telephone (44) 161 622 4422
Fax: (44) 161 622 4420
Zetex GmbH
Streitfeldstraße 19
D-81673 München
Zetex Inc
700 Veterans Memorial Hwy
Hauppauge, NY11788
Zetex (Asia) Ltd
3701-04 Metroplaza, Tower 1
Hing Fong Road
Kwai Fong
Hong Kong
Telephone: (852) 26100 611
Fax: (852) 24250 494
Germany
Telefon: (49) 89 45 49 49 0
Fax: (49) 89 45 49 49 49
USA
Telephone: (631) 360 2222
Fax: (631) 360 8222
These offices are supported by agents and distributors in major countries world-wide.
This publication is issued to provide outline information only which (unless agreed by the Company in writing) may not be used, applied or reproduced
for any purpose or form part of any order or contract or be regarded as a representation relating to the products or services concerned. The Company
reserves the right to alter without notice the specification, design, price or conditions of supply of any product or service.
For the latest product information, log on to www.zetex.com
PROVISIONAL ISSUE A - DECEMBER 2001
9
相关型号：
©2020 ICPDF网 联系我们和版权申明