MAX1730EUB+ [MAXIM]
Switched Capacitor Regulator, 2500kHz Switching Freq-Max, PDSO10, EXPOSED PAD, UMAX-10;
| 型号： | MAX1730EUB+ |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Switched Capacitor Regulator, 2500kHz Switching Freq-Max, PDSO10, EXPOSED PAD, UMAX-10 光电二极管 |
| 文件： | 总8页 (文件大小：179K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-1618; Rev 0; 4/00
50mA Regulated Step-Down Charge Pump
for 1.8V or 1.9V Logic
General Description
Features
ꢀ > 85% Peak Efficiency
The MAX1730 regulated step-down charge pump gen-
erates up to 50mA at fixed output voltages of 1.8V or
1.9V from an input voltage in the 2.7V to 5.5V range.
Specifically designed to provide high-efficiency logic
supplies in applications that demand a compact
design, the MAX1730 employs fractional conversion
techniques to provide efficiency exceeding that of a lin-
ear regulator.
ꢀ 50mA Guaranteed Output Current
ꢀ Dual-Mode 1.8V or 1.9V Output
ꢀ ±±% Output Voltaꢀe Accuracy
ꢀ Up to 2MHz Operatinꢀ Frequency
ꢀ Small 0.22µF Capacitors
The MAX1730 operates at up to 2MHz, permitting the
use of small 0.22µF flying capacitors while maintaining
low 75µA quiescent supply current. Proprietary soft-
start circuitry prevents excessive current from being
drawn from the supply during startup, making the
MAX1730 compatible with higher impedance sources
such as alkaline and lithium-ion cells.
ꢀ No Inductor Required
ꢀ 2.7V to 5.5V Input Voltaꢀe Ranꢀe
ꢀ Output Disconnects from Input in Shutdown Mode
ꢀ Small 10-Pin µMAX Packaꢀe (1.09mm max heiꢀht)
The MAX1730 is available in a space-saving 10-pin
µMAX package that is only 1.09mm high and occupies
one-half the area of an 8-pin SO.
Applications
Ordering Information
Low-Voltage Logic Supplies
Wireless Handsets
PDAs
PART
TEMP. RANGE
PIN-PACKAGE
MAX1730EUB
-40°C to +85°C
10 µMAX
PC Cards
Hand-Held Instruments
Pin Configuration
Typical Operating Circuit
TOP VIEW
INPUT
2.7V TO 5.5V
1 F
FB
SHDN
C1P
1
2
3
4
5
10 IN
OUTPUT
9
8
7
6
OUT
C2P
1.8V OR 1.9V, UP TO 50mA
IN
MAX1730
OUT
C2P
SHDN
4.7 F
C1N
C2N
PGND
MAX1730
GND
C1P
MAX
0.22 F
0.22 F
C1N
FB
C2N
PGND
GND
________________________________________________________________ Maxim Integrated Products
1
For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
50mA Regulated Step-Down Charge Pump
for 1.8V or 1.9V Logic
ABSOLUTE MAXIMUM RATINGS
IN, OUT, SHDN, FB to GND .....................................-0.3V to +6V
Junction Temperature......................................................+150°C
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature Range (soldering, 10s)......................+300°C
C1P, C1N, C2P, C2N to GND......................-0.3V to (V + 0.3V)
GND to PGND..................................................................... 0.3V
Output Short-Circuit Duration ........................................Indefinite
IN
Continuous Power Dissipation (T = +70°C)
A
10-Pin µMAX (derate 5.6mW/°C above +70°C)...........444mW
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
(V = +3.6V, FB = GND, SHDN = IN, T = 0°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.)
IN
A
A
PARAMETER
SYMBOL
CONDITIONS
MIN
2.7
TYP
MAX
5.5
UNITS
Input Voltage Range
V
IN
V
V
Input Undervoltage Lockout
Falling edge (100mV hysteresis)
2.3
2.6
FB = GND
FB = IN
1.746
1.843
1.80
1.90
1.854
1.957
V
= 2.7V to 5.5V,
= 0 to 50mA
IN
Output Voltage
V
OUT
V
I
OUT
OUT forced to 1.8V, V = 1.8V to 5.5V,
IN
SHDN = GND
Output Leakage Current
1
5
µA
No-Load Supply Current
Shutdown Supply Current
Output Short-Circuit Current
Oscillator Frequency
75
1
150
5
µA
µA
SHDN = IN
V
V
= 4.2V, SHDN = GND, V
= 1.8V or GND
IN
OUT
= GND
45
125
2.5
mA
MHz
°C
OUT
1.5
2.0
150
Thermal Shutdown Threshold
Thermal Shutdown Threshold
Hysteresis
15
°C
V
From 1:1 to 2:3
From 2:3 to 1:2
3.1
3.2
4.12
4.1
3.35
4.30
V
IN
Transition Voltage
FB = GND
(V Rising)
IN
4.00
Startup Timer
ms
V
V
V
V
= 2.7V to 5.5V
1.4
-1
SHDN Logic Input High Voltage
SHDN Logic Input Low Voltage
Shutdown Logic Input Current
IH
IN
V
IL
SHDN
= 2.7V to 5.5V
0.6
1
V
IN
I
µA
SHDN = IN or GND
2
_______________________________________________________________________________________
50mA Regulated Step-Down Charge Pump
for 1.8V or 1.9V Logic
ELECTRICAL CHARACTERISTICS
(V = +3.6V, FB = GND, SHDN = IN, T = -40°C to +85°C, unless otherwise noted.) (Note 1)
IN
A
PARAMETER
SYMBOL
CONDITIONS
MIN
2.7
MAX
5.5
UNITS
Input Voltage Range
V
IN
V
V
Input Undervoltage Lockout
Falling edge (100mV hysteresis)
2.3
2.6
FB = GND
FB = IN
1.746
1.843
1.854
1.957
V
= 2.7V to 5.5V,
= 0 to 50mA
IN
Output Voltage
V
OUT
V
I
OUT
OUT forced to 1.8V, V = 1.8V to 5.5V,
IN
SHDN = GND
Output Leakage Current
5
µA
No-Load Supply Current
Shutdown Supply Current
Output Short-Circuit Current
Oscillator Frequency
150
5
µA
µA
SHDN = IN
V
V
= 4.2V, SHDN = GND
IN
= GND
125
2.5
mA
MHz
OUT
f
1.5
3.1
From 1:1 to 2:3
From 2:3 to 1:2
3.35
4.30
V
IN
Transition Voltage
FB = GND
V
(V Rising)
IN
4.00
1.4
V
IH
V
V
= 2.7V to 5.5V
V
V
SHDN Logic Input High Voltage
SHDN Logic Input Low Voltage
Shutdown Logic Input Current
IN
V
IL
SHDN
= 2.7V to 5.5V
0.6
1
IN
I
-1
µA
SHDN = IN or GND
Note 1: Specifications to -40°C are guaranteed by design, not production tested.
_______________________________________________________________________________________
±
50mA Regulated Step-Down Charge Pump
for 1.8V or 1.9V Logic
Typical Operating Characteristics
(V = +3.6V, FB = GND, SHDN = IN, C = 1µF, C1 = C2 = 0.22µF, C
= 4.7µF, T = +25°C, unless otherwise noted.)
IN
IN
OUT
A
EFFICIENCY
vs. OUTPUT CURRENT
EFFICIENCY vs. INPUT VOLTAGE
EFFICIENCY vs. INPUT VOLTAGE
100
95
90
85
80
75
70
65
60
55
50
100
95
90
85
80
75
70
65
60
55
50
100
I
= 25mA
I
= 50mA
OUT
OUT
V
= 3.3V
IN
90
80
70
60
50
40
30
20
10
0
V
= 3.6V
IN
V
= 5.0V
IN
V
= 2.7V
IN
0.1
1
10
100
1000
2.5
3.0
3.5
4.0
4.5
5.0
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
OUTPUT CURRENT (mA)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
OUTPUT VOLTAGE
vs. OUTPUT CURRENT
INPUT CURRENT vs. INPUT VOLTAGE
OUTPUT VOLTAGE vs. INPUT VOLTAGE
1.85
70
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
60
50
40
30
20
10
0
NO-LOAD
V
= 5.0V
IN
1.83
1.81
1.79
1.77
1.75
SUPPLY CURRENT
V
= 3.3V
IN
V
= 2.7V
IN
SHUTDOWN CURRENT
I
= 0 to 50mA
5 6
OUT
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
0.1
1
10
100
1000
0
1
2
3
4
OUTPUT CURRENT (mA)
INPUT VOLTAGE (V)
4
_______________________________________________________________________________________
50mA Regulated Step-Down Charge Pump
for 1.8V or 1.9V Logic
Typical Operating Characteristics (continued)
(V = +3.6V, FB = GND, SHDN = IN, C = 1µF, C1 = C2 = 0.22µF, C
= 4.7µF, T = +25°C, unless otherwise noted.)
A
IN
IN
OUT
STARTUP AND SHUTDOWN RESPONSE
LINE-TRANSIENT RESPONSE
LOAD-TRANSIENT RESPONSE
MAX1730 TOC09
MAX1730 TOC07
MAX1730 TOC08
R
= 72
L
4V
50mA
OUT
5mA
I
V
IN
V
O
3V
1V/div
I
IN
50mA/div
V
V
OUT
AC-COUPLED
20mV/div
OUT
AC-COUPLED
50mV/div
V
SHDN
5V/div
100 s/div
10 s/div
10 s/div
Pin Description
PIN
NAME
FUNCTION
Feedback Input. Connect FB to GND for a 1.8V output. Connect FB to IN for a 1.9V output. Do not leave FB
unconnected.
1
2
FB
Active-Low Shutdown Input. Connect to logic control or to IN for normal operation. OUT disconnects from the
input in shutdown and goes to high impedance.
SHDN
3
4
5
6
7
8
9
C1P
C1N
GND
PGND
C2N
C2P
C1 Flying Capacitor Positive Connection
C1 Flying Capacitor Negative Connection
Ground
Power Ground
C2 Flying Capacitor Negative Connection
C2 Flying Capacitor Positive Connection
Output. Bypass to GND with a 4.7µF or greater capacitor.
OUT
Input Supply. Connect to a +2.7V to +5.5V supply. Bypass to GND with a 1µF ceramic capacitor as close to
the IC as possible.
10
IN
_______________________________________________________________________________________
5
50mA Regulated Step-Down Charge Pump
for 1.8V or 1.9V Logic
Functional Diagram
OUT
C1P
C1N
FB
FB CONTROL
DRIVERS
VREF
+
MAX1730
OSCILLATOR
SWITCH ARRAY
C2P
CONTROL LOGIC
C2N
SHUTDOWN
PGND
SHDN
GND
IN
Figure 2 shows the 3:2 charge-pump configuration. C1
and C2 charge in parallel between IN and OUT during
the first phase. In the second phase, C1 and C2 connect
in series between OUT and GND.
Detailed Description
The MAX1730 step-down charge pump automatically
switches between charge pump configurations (Figures
1, 2, and 3) and utilizes pulse-skipping pulse-frequency
modulation (PFM) to provide a regulated output voltage
with high efficiency. The output voltage is pin-selectable
to 1.8V or 1.9V. The MAX1730 accepts inputs between
2.7V and 5.5V and guarantees up to 50mA output cur-
rent.
Figure 3 shows the 2:1 charge-pump configuration. C1
and C2 charge in parallel between IN and OUT during
the first phase. In the second phase, C1 and C2 connect
in parallel between OUT and GND.
Pulse-Skipping PFM and Mode
Transitions
Charge-Pump Configurations
Charge pumps work by passing energy through capaci-
tors. They generally work in two phases. In the first phase,
the input source charges the flying capacitors. The input
capacitor helps reduce the source’s input impedance. In
the second phase, the switching capacitors transfer their
charge to the output as needed.
In the MAX1730, pulse-skipping PFM mode pauses the
oscillator when the output is in regulation. Using the 2:1
charge-pump configuration as an example, when the
output is set to half the input, the switching frequency is
near the oscillator frequency. However, for outputs below
half the input, switching pauses once the desired output
level is achieved. With no output current, the device
switches occasionally. With higher levels of current, the
switching frequency increases to supply the load.
Figure 1 shows the 1:1 charge-pump configuration. C1
and C2 charge in parallel between IN and GND during
the first phase. In the second phase, C1 and C2 connect
in parallel between OUT and GND.
6
_______________________________________________________________________________________
50mA Regulated Step-Down Charge Pump
for 1.8V or 1.9V Logic
V
IN
V
= V
IN
OUT
C
C
OUT
IN
C1
C2
NOTE: SWITCH STATES SET FOR STAGE 1.
ALL SWITCHES REVERSE STATE FOR STAGE 2.
Figure 1. 1:1 Capacitor Configuration
V
IN
V
IN
C
IN
C
IN
C1
C2
C2
C1
2
V
IN
V
=
OUT
1
2
3
V
=
V
IN
OUT
C
OUT
C
OUT
NOTE: SWITCH STATES SET FOR STAGE 1.
NOTE: SWITCH STATES SET FOR STAGE 1.
ALL SWITCHES REVERSE STATE FOR STAGE 2.
ALL SWITCHES REVERSE STATE FOR STAGE 2.
Figure 2. 3:2 Capacitor Configuration
Figure 3. 2:1 Capacitor Configuration
To maximize efficiency, the MAX1730 automatically
switches between charge-pump configurations (Figures
1, 2, and 3). Efficiency is greatest when the IN/OUT volt-
age ratio is close to the voltage ratio of the selected
capacitor configuration and decreases for output volt-
ages lower than the divider ratio. To choose between
configurations, the MAX1730 senses the input voltage
and the output voltage. The MAX1730 uses a control
scheme with hysteresis to prevent oscillation between
capacitor configurations.
Applications Information
Setting the Output Voltage
For an output voltage of 1.8V, connect FB to GND. For
an output voltage of 1.9V, connect FB to IN.
_______________________________________________________________________________________
7
50mA Regulated Step-Down Charge Pump
for 1.8V or 1.9V Logic
Shutdown
The MAX1730 features an active-low shutdown pin
(SHDN) to decrease supply current to below 5µA.
When in shutdown, the output disconnects from the
input and OUT goes to high impedance.
Layout Considerations
The MAX1730’s high-frequency operation demands
careful layout. All components should be placed as
close to the IC as possible, with priority going to CIN,
C1, and C2. Traces should be kept short, wide, and as
straight as possible. Connect PGND and GND together
with a low-impedance ground plane.
Capacitor Selection
The input capacitor provides the charge pump with a low-
impedance supply. For most applications, a 1µF ceramic
capacitor is adequate. Lower-value capacitors and those
with higher ESR may be inadequate for proper operation
and may result in lower output current capability and
higher output ripple.
Chip Information
TRANSISTOR COUNT: 2295
To reduce the output voltage ripple, the value of the
output capacitor should exceed that of the flying
capacitors (C1 + C2) by 10:1 or more. Values for C1
and C2 between 0.22µF and 0.47µF are recommended
for most applications. Use ceramic capacitors to
increase maximum output current and improve efficiency.
Package Information
Note: The MAX1730 does not have an exposed pad.
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.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2000 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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