MAX1701EEE+ [MAXIM]
Switching Regulator, 340kHz Switching Freq-Max, PDSO16, 0.150 INCH, 0.025 INCH PITCH, QSOP-16;
| 型号： | MAX1701EEE+ |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Switching Regulator, 340kHz Switching Freq-Max, PDSO16, 0.150 INCH, 0.025 INCH PITCH, QSOP-16 开关 光电二极管 |
| 文件： | 总16页 (文件大小：251K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-4759; Rev 1; 1/99
1 -Ce ll t o 3 -Ce ll, Hig h -P o w e r (1 A),
Lo w -No is e , S t e p -Up DC-DC Co n ve rt e rs
/MAX701
Ge n e ra l De s c rip t io n
Fe a t u re s
The MAX1700/MAX1701 are high-efficiency, low-noise,
step-up DC-DC converters intended for use in battery-
powered wireless applications. They use a synchro-
nous-rectified pulse-width-modulation (PWM) boost
topology to generate 2.5V to 5.5V outputs from battery
inputs such as one to three NiCd/NiMH cells or one Li-
Ion cell. Both devices have an internal 1A, 130mΩ N-
c ha nne l MOSFET s witc h a nd a 250mΩ P-c ha nne l
synchronous rectifier.
♦ Up to 96% Efficiency
♦ 1.1 V Guaranteed Start-Up
IN
♦ 0.7V to 5.5V Input Range
♦ Up to 800mA Output
♦ Step-Up Output (adjustable from 2.5V to 5.5V)
♦ PWM/PFM Synchronous-Rectified Topology
♦ External Clock or Internal 300kHz Oscillator
♦ 3µA Logic-Controlled Shutdown
With their internal synchronous rectifier, the MAX1700/
MAX1701 deliver 5% better efficiency than similar non-
synchronous converters. They also feature a pulse-
frequency-modulation (PFM) standby mode to improve
efficiency at light loads, and a 3µA shutdown mode.
♦ Power-Good Output (MAX1701)
♦ Low-Battery Comparator (MAX1701)
♦ Uncommitted Gain Block (MAX1701)
The MAX1700/MAX1701 come in 16-pin QSOP pack-
ages (which occupy the same space as an 8-pin SO).
The MAX1701 includes two comparators to generate
power-good and low-battery warning outputs. It also
contains a gain block that can be used to build a linear
regulator using an external P-channel pass device.
Ord e rin g In fo rm a t io n
For higher-power outputs, refer to the MAX1703. For
dual outputs (step-up and linear regulator), refer to the
MAX1705/MAX1706. For an on-board analog-to-digital
converter, refer to the MAX848/MAX849.
PART
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 QSOP
MAX1700EEE
MAX1701EEE
16 QSOP
The MAX1701 evaluation kit is available to speed design
time.
Typ ic a l Op e ra t in g Circ u it
Ap p lic a t io n s
Digital Cordless Phones Personal Communicators
INPUT
0.7V TO 5.5V
PCS Phones
Palmtop Computers
Wireless Handsets
Two-Way Pagers
Hand-Held Instruments
OUTPUT
3.3V OR ADJ
UP TO 800mA
P in Co n fig u ra t io n s
MAX1700
ONA
ON
TOP VIEW
OFF
ON
LX
OFF
I.C.
I.C.
1
2
3
4
5
6
7
8
16 I.C.
ONB
15 POUT
14 OUT
PWM
REF
OR
CLK/SEL
POUT
OUT
PFM
SYNC
CLK/SEL
GND
I.C.
MAX1700
13 LX
12 PGND
11 FB
REF
FB GND PGND
ONB
10 I.C.
ONA
9 I.C.
QSOP
I.C. = INTERNAL CONNECTION. LEAVE OPEN OR CONNECT TO GND
Pin Configurations continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
1 -Ce ll t o 3 -Ce ll, Hig h -P o w e r (1 A),
Lo w -No is e , S t e p -Up DC-DC Co n ve rt e rs
ABSOLUTE MAXIMUM RATINGS
Operating Temperature Ranges
ONA, ONB, OUT, AO, POK, LBO to GND...................-0.3V, +6V
MAX1700EEE, MAX1701EEE ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
PGND to GND.....................................................................±0.3V
LX to PGND.....................................................-0.3V,V
+0.3V
POUT
CLK/SEL, AIN, REF, FB, LBP, LBN, POUT to GND............-0.3V,
+0.3V ...................................................................................
V
OUT
Continuous Power Dissipation (T =+70°C)
A
16-QSOP (Derate 8.30mW/°C above +70°C) ...............667mW
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
(CLK/SEL = ONA = ONB = FB = PGND = GND, OUT = POUT, V
= 3.6V (Note 6); MAX1701: AIN = LBN = GND, LBP = REF,
OUT
T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.)
A
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
DC-DC CONVERTER
Input Voltage Range (Note 1)
0.7
0.9
5.5
1.1
V
V
/MAX701
Minimum Start-Up Voltage
(Note 2)
I
< 1mA, T = +25°C
A
LOAD
Frequency in Start-Up Mode
Output Voltage (Note 3)
V
V
= 1.5V
40
150
3.30
300
3.38
kHz
V
OUT
< 0.1V, CLK/SEL = OUT, V
= 2.4V,
BATT
FB
3.17
includes load regulation error for 0A ≤ I ≤ 0.55A
LX
Adjustable output, CLK/SEL = OUT, V
includes load regulation error for 0A ≤ I ≤ 0.55A
= 2.4V,
BATT
FB Regulation Voltage
1.210
1.24
0.01
1.255
V
LX
FB Input Current
V
FB
= 1.25V
20
nA
V
Output Voltage Adjust Range
2.5
2.0
5.5
Output Voltage Lockout
Threshold
(Note 4)
2.15
2.3
V
%
Load Regulation (Note 5)
CLK/SEL = OUT, No load to full load
-1.6
0.1
3
MAX1700
MAX1701
20
20
Supply Current in Shutdown
V
ONB
= 3.6V
µA
CLK/SEL = GND (MAX1700)
CLK/SEL = GND (MAX1701)
CLK/SEL = OUT (MAX1700)
CLK/SEL = OUT (MAX1701)
35
70
Supply Current in Low-Power
Mode (Note 6)
µA
µA
55
110
250
300
125
140
Supply Current in Low-Noise
Mode (Note 6)
DC-DC SWITCHES
POUT Leakage Current
LX Leakage Current
V
= 0V, V
= 5.5V
0.1
0.1
20
20
µA
µA
LX
OUT
V
LX
= V
= V
= 5.5V
OUT
ONB
CLK/SEL = GND
CLK/SEL = OUT
0.2
0.45
0.28
0.5
N-channel
P-channel
Switch On-Resistance
0.13
0.25
1300
400
Ω
CLK/SEL = OUT
CLK/SEL = GND
CLK/SEL = GND
1100
250
20
1600
550
120
N-Channel Current Limit
mA
mA
P-Channel Turn-Off Current
2
_______________________________________________________________________________________
1 -Ce ll t o 3 -Ce ll, Hig h -P o w e r (1 A),
Lo w -No is e , S t e p -Up DC-DC Co n ve rt e rs
/MAX701
ELECTRICAL CHARACTERISTICS (continued)
(CLK/SEL = ONA = ONB = FB = PGND = GND, OUT = POUT, V
= 3.6V (Note 6); MAX1701: AIN = LBN = GND, LBP = REF,
OUT
T
A
= 0°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.)
A
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
GAIN BLOCK (MAX1701)
AIN Reference Voltage
AIN Input Current
I
= 20µA
1.237
-30
5
1.25
1.263
30
V
nA
AO
V
= 1.5V
AIN
Transconductance
10µA < I = 100µA
9
16
mmho
V
AO
AO Output Low Voltage
AO Output High Leakage
POWER GOOD (MAX1701)
Internal Trip Level
V
= 0.7V, I = 100µA
0.1
0.4
1
AIN
AO
V
= 1.5V, V = 5.5V
0.01
µA
AIN
AO
Rising V
, V < 0.1V
2.93
1.1
2.97
1.12
0.03
0.01
3.02
1.14
0.4
1
V
V
OUT FB
External Trip Level
Rising V
FB
POK Low Voltage
I
= 1mA, V
= 3.6V or I
= 20µA, V = 1V
OUT
V
SINK
OUT
SINK
POK High Leakage Current
LOW-BATTERY COMPARATOR
LBN, LBP Input Offset
V
= V
= 5.5V
µA
OUT
POK
LBP falling, 15mV hysteresis
-5
±0.5
5
mV
V
LBN, LBP Common Mode
Range
To maintain input offset < ±5mV (at least one input must
be within this range)
0.5
1.5
LBO Output Low Voltage
LBO High Leakage
I
= 1mA, V
= 3.6V or I
= 20µA, V = 1V
OUT
0.03
0.01
0.4
1
V
SINK
OUT
SINK
V
= V
= 5V
µA
nA
OUT
LBO
LBN, LBP Input Current
REFERENCE
V
= V
= 1.5V
20
LBP
LBN
Reference Output Voltage
REF Load Regulation
REF Supply Rejection
LOGIC AND CONTROL INPUTS
I
= 0
1.237
1.250
5
1.263
15
V
REF
-1µA < I
< 50µA
mV
mV
REF
2.5V < V
< 5V
0.2
5
OUT
0.2V
1.2V < V
< 5.5V, ONA and ONB
< 5.5V, CLK/SEL
OUT
OUT
Input Low Voltage (Note 7)
V
V
2.5V < V
0.2V
OUT
OUT
Input High Voltage (Note 7)
0.8V
OUT
1.2V < V
< 5.5V, ONA and ONB
< 5.5V, CLK/SEL
OUT
2.5V < V
0.8V
OUT
OUT
Logic Input Current
-1
260
80
1
µA
kHz
%
ONA, ONB, and CLK/SEL
Internal Oscillator Frequency
Oscillator Maximum Duty Cycle
CLK/SEL = OUT
300
86
340
90
External Clock Frequency
Range
200
400
kHz
ns
Minimum CLK/SEL Pulse Width
200
100
Maximum CLK/SEL Rise/Fall
Time
ns
_______________________________________________________________________________________
3
1 -Ce ll t o 3 -Ce ll, Hig h -P o w e r (1 A),
Lo w -No is e , S t e p -Up DC-DC Co n ve rt e rs
ELECTRICAL CHARACTERISTICS (continued)
(CLK/SEL = ONA = ONB = FB = PGND = GND, OUT = POUT, V
= 3.6V (Note 6); MAX1701: AIN = LBN = GND, LBP = REF,
OUT
T
A
= -40°C to +85°C, unless otherwise noted.) (Note 8)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
DC-DC CONVERTER
V
< 0.1V, CLK/SEL = OUT, V
= 2.4V, includes load
FB
BATT
Output Voltage (Note 3)
3.17
1.20
2.0
3.38
1.27
2.3
V
V
regulation error for 0A ≤ I ≤ 0.55A
LX
Adjustable output, CLK/SEL = OUT, V
includes load regulation error for 0A ≤ I ≤ 0.55A
= 2.4V,
BATT
FB Regulation Voltage
LX
Output Voltage Lockout
Threshold
(Note 4)
V
Supply Current in Shutdown
V
= 3.6V
20
70
µA
µA
ONB
CLK/SEL = GND (MAX1700)
CLK/SEL = GND (MAX1701)
CLK/SEL = OUT (MAX1700)
CLK/SEL = OUT (MAX1701)
Supply Current in Low-Power
Mode (Note 6)
110
250
300
Supply Current in Low-Noise
Mode (Note 6)
µA
/MAX701
DC-DC SWITCHES
CLK/SEL = GND
CLK/SEL = OUT
0.45
0.28
0.5
N-channel
Switch On-Resistance
Ω
P-channel
CLK/SEL = OUT
CLK/SEL = GND
1100
250
1800
600
N-Channel Current Limit
mA
GAIN BLOCK (MAX1701)
AIN Reference Voltage
Transconductance
I
= 20µA
1.23
5
1.27
16
V
AO
10µA < I < 100µA
mmho
AO
POWER-GOOD (MAX1701)
Internal Trip Level
Rising V
, V < 0.1V
2.92
1.1
3.03
1.14
V
V
OUT FB
External Trip Level
Rising V
FB
LOW-BATTERY COMPARATOR (MAX1701)
LBN, LBP Input Offset
LBP falling, 15mV hysteresis
-5
5
mV
V
LBN, LBP Common Mode
Range
To maintain input offset < ±5mV (at least one input must
be within this range)
0.5
1.5
REFERENCE
Reference Output Voltage
I
= 0
1.23
1.27
V
REF
4
_______________________________________________________________________________________
1 -Ce ll t o 3 -Ce ll, Hig h -P o w e r (1 A),
Lo w -No is e , S t e p -Up DC-DC Co n ve rt e rs
/MAX701
ELECTRICAL CHARACTERISTICS (continued)
(CLK/SEL = ONA = ONB = FB = PGND = GND, OUT = POUT, V
= 3.6V, MAX1701: AIN = LBN = GND, LBP = REF,
OUT
T
A
= -40°C to +85°C, unless otherwise noted.) (Note 8)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
LOGIC AND CONTROL INPUTS
0.2V
1.2V < V
< 5.5V, ONA and ONB
< 5.5V, CLK/SEL
OUT
OUT
Input Low Voltage (Note 7)
V
V
2.5V < V
0.2V
OUT
OUT
0.8V
1.2V < V
< 5.5V, ONA and ONB
< 5.5V, CLK/SEL
OUT
OUT
Input High Voltage (Note 7)
2.5V < V
0.8V
OUT
OUT
Logic Input Current
-1
260
80
1
µA
kHz
%
ONA, ONB, and CLK/SEL
Internal Oscillator Frequency
Oscillator Maximum Duty Cycle
CLK/SEL = OUT
340
92
External Clock Frequency
Range
200
400
kHz
Note 1: Operating voltage. Since the regulator is bootstrapped to the output, once started it will operate down to 0.7V input.
Note 2: Start-up is tested with the circuit of Figure 2.
Note 3: In low-power mode (CLK/SEL = GND), the output voltage regulates 1% higher than low-noise mode (CLK/SEL = OUT or
synchronized).
Note 4: The regulator is in start-up mode until this voltage is reached. Do not apply full load current.
Note 5: Load regulation is measured from no-load to full load where full load is determined by the N-channel switch current limit.
Note 6: Supply current from the 3.30V output is measured between the 3.30V output and the OUT pin. This current correlates
directly to the actual battery supply current, but is reduced in value according to the step-up ratio and efficiency. Set V
OUT
= 3.6V to keep the internal switch open when measuring the current into the device.
Note 7: ONA and ONB have hysteresis of approximately 0.15xV
.
OUT
Note 8: Specifications to -40°C are guaranteed by design and not production tested.
Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s
(T = +25°C, unless otherwise noted.)
A
MAX1701
SHUTDOWN CURRENT
vs. INPUT VOLTAGE (V)
EFFICIENCY vs. LOAD CURRENT
(V = 5V)
EFFICIENCY vs. LOAD CURRENT
(V = 3.3V)
OUT
OUT
100
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0
100
V
IN
= 3.6V
V
IN
= 2.4V
90
80
70
60
50
T = 25°C
90
80
V
IN
= 2.4V
V
IN
= 1.2V
T = 85°C
70
V
IN
= 1.2V
T = -40°C
60
50
40
V
IN
= 0.9V
PFM
PWM
40
30
PFM
PWM
0
1
2
3
4
5
6
0.1
1
10
100
1000
0.1
1
10
100
1000
INPUT VOLTAGE (V)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
_______________________________________________________________________________________
5
1 -Ce ll t o 3 -Ce ll, Hig h -P o w e r (1 A),
Lo w -No is e , S t e p -Up DC-DC Co n ve rt e rs
Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s (c o n t in u e d )
(T = +25°C, unless otherwise noted.)
A
REFERENCE VOLTAGE
REFERENCE VOLTAGE
vs. TEMPERATURE
vs. REFERENCE CURRENT
FREQUENCY vs. TEMPERATURE
1.254
1.254
1.252
1.250
1.248
1.246
1.244
325
320
315
310
305
300
295
290
285
280
V
OUT
= 5V
1.252
1.250
1.248
1.246
1.244
V
OUT
= 3.3V
-40 -20
0
20
40
60
80 100
0
10 20 30 40 50 60 70 80
-40 -20
0
20 40 60 80 100 120 140
TEMPERATURE (°C)
REFERENCE CURRENT (µA)
TEMPERATURE (°C)
/MAX701
START-UP INPUT VOLTAGE
vs. OUTPUT CURRENT
PEAK INDUCTOR CURRENT
vs. OUTPUT VOLTAGE
2.3
1.6
1.4
1.2
1.0
0.8
0.6
0.4
NO-LOAD START-UP:
1.0V AT -40°C
0.79 AT +25°C
0.64V AT +85°C
CONSTANT-CURRENT LOAD
2.1
1.9
PWM
1.7
1.5
1.3
V
OUT
= 3.3V
L = 10µH
D1 = MBR0520L
1.1
0.9
0.7
0.5
T = -40°C
A
T = +25°C
A
T = +85°C
PFM
5
A
0.2
2.5
0.01
0.1
1
10
100
1000
3
3.5
4
4.5
5.5
OUTPUT CURRENT (mA)
OUTPUT VOLTAGE (V)
HEAVY-LOAD SWITCHING WAVEFORMS
(V = 3.3V)
OUT
LINE-TRANSIENT RESPONSE
MAX1700-08
MAX1700-09
V
OUT
A
B
0V
0A
A
B
0V
C
1µs/div
5ms/div
V
IN
= 1.1V, I = 200mA, V = 3.3V
OUT OUT
I
= 0mA, V = 3.3V
OUT OUT
A = LX VOLTAGE, 2V/div
B = INDUCTOR CURRENT, 0.5A/div
C = V RIPPLE, 50mV/div, AC COUPLED
A = V , 1.1V TO 2.1V, 1V/div
IN
B = V RIPPLE, 50mV/div, AC COUPLED
OUT
OUT
6
_______________________________________________________________________________________
1 -Ce ll t o 3 -Ce ll, Hig h -P o w e r (1 A),
Lo w -No is e , S t e p -Up DC-DC Co n ve rt e rs
/MAX701
Typ ic a l Op e ra t in g Ch a ra c t e ris t ic s (c o n t in u e d )
(Circuit of Figure 1, T = +25°C, unless otherwise noted.)
A
POWER-ON DELAY
(PFM MODE)
LOAD-TRANSIENT RESPONSE
MAX1700-10
MAX1700-11
3.3V
0mA
A
B
A
B
200mA
0A
C
5ms/div
2ms/div
A = V , 2V/div
V
IN
= 1.1V, V = 3.3V
OUT
ON1
B = V , 1V/div
C = INPUT CURRENT, 0.2A/div
OUT
A = LOAD CURRENT, 0mA TO 200mA, 0.2A/div
B = V RIPPLE, 50mV/div, AC COUPLED
OUT
DECT LOAD-TRANSIENT RESPONSE
GSM LOAD-TRANSIENT RESPONSE
MAX1700-13
MAX1700-12
3.3V
5V
A
B
A
B
0A
0A
2ms/div
= 1.2V, V = 3.3V, C = 440µF
1ms/div
V
IN
V
IN
= 3.6V, V = 5V, C = 440µF
OUT OUT
OUT
OUT
A = V RIPPLE, 200mV/div, AC COUPLED
OUT
A = V RIPPLE, 200mV/div, AC COUPLED
OUT
B = LOAD CURRENT, 50mA TO 400mA, 0.2A/div,
B = LOAD CURRENT, 100mA TO 1A, 0.5A/div,
PULSE WIDTH = 416µs
PULSE WIDTH = 577µs
NOISE SPECTRUM
(V = 3.3V, V = 1.2V, R
= 50Ω)
OUT
IN
LOAD
2.7
0
0.1k
1k
10k
100k
1M
FREQUENCY (Hz)
_______________________________________________________________________________________
7
1 -Ce ll t o 3 -Ce ll, Hig h -P o w e r (1 A),
Lo w -No is e , S t e p -Up DC-DC Co n ve rt e rs
P in De s c rip t io n
PIN
NAME
FUNCTION
MAX1700
MAX1701
—
—
1
2
LBP
Low-Battery Comparator Non-Inverting Input
Low-Battery Comparator Inverting Input
LBN
Reference Output. Bypass with a 0.22µF capacitor to GND. REF can source up to
50µA.
3
4
3
4
REF
Switching-Mode Selection and External-Clock Synchronization Inputs.
• CLK/SEL=Low: Low-power, delivers up to 10% of full load current.
• CLK/SEL=High: High-power PWM mode. Full output power available. Operates in
low-noise, constant-frequency mode.
• CLK/SEL=External Clock: High-power PWM mode with the internal oscillator
synchronized to the external clock.
CLK/SEL
Turning on with CLK/SEL=0V also serves as a soft-start function since peak inductor
current is limited to 25% of that allowed in PWM mode.
5
5
6
GND
POK
Ground
/MAX701
Power-Okay Comparator Output. Open drain N-channel output is low when V
10% below regulation point. No internal delay is provided.
is
OUT
—
Shutdown Input. When ONB =high and ONA=low, the IC is off and the load is connect-
ed to the battery through the Schottky diode.
7
7
ONB
8
8
9
ONA
AO
Turn ON Input. When ONA=high or ONB =low, the IC turns on.
—
Gain Block Output. This open-drain output sinks when V
<V
.
AIN
REF
Gain Block AIN input. When AIN is low, AO sinks current. The transconductance from
AIN to AO is 9mmhos.
—
10
AIN
DC-DC Converter Dual-Mode Feedback Input. For a fixed output voltage of +3.3V,
connect FB to GND. For adjustable output, connect a divider between POUT and GND
to set the output voltage in the range of 2.5V to 5V.
11
11
FB
12
13
14
12
13
14
PGND
LX
Source of N-Channel Power MOSFET Switch. Connect to high-current ground path.
Drain of P-Channel Synchronous Rectifier and N-Channel Switch
Output Sense Input. Power source for the IC.
OUT
Source of P-Channel Synchronous Rectifier MOSFET Switch. Connect an external
Schottky diode from LX to POUT.
15
—
15
16
—
POUT
LBO
I.C.
Low-Battery Comparator Output. Open-drain N-channel output is low when LBN > LBP
Input hysteresis is 15mV.
1, 2, 6, 9,
10, 16
Internal Connection. Leave open or connect to GND.
8
_______________________________________________________________________________________
1 -Ce ll t o 3 -Ce ll, Hig h -P o w e r (1 A),
Lo w -No is e , S t e p -Up DC-DC Co n ve rt e rs
/MAX701
UNDERVOLTAGE LOCKOUT
OUT
IC PWR
PFM/PWM
POUT
LX
2.25V
CONTROLLER
START-UP
PCH
0.25Ω
D
EN
Q
Q
OSCILLATOR
ONA
ONB
REF
ON
RDY
REFERENCE
EN
OSC
EN
1.25V
NCH
0.13Ω
REF
OSCILLATOR
300kHz
Q
GND
CLK/SEL
PFM/PWM
MODE
FB
PGND
POK*
FEEDBACK
FEEDBACK AND
POWER-GOOD
SELECT
FB
N
N
AIN*
AO*
GAIN
BLOCK
REF
COMPARATOR
LBP*
LBN*
LBO*
N
*MAX1701 ONLY
Figure 1. Functional Diagram
power operation, as well as low-quiescent current for
maximum battery life during standby and shutdown
modes. They feature constant-frequency (300kHz), low-
noise PWM operation with up to 800mA output capabili-
ty. See Table 1 for typical available output current. A
low-quiescent-current, low-power mode offers an out-
put up to 100mA and reduces quiescent power con-
sumption to 200µW. In shutdown mode, the quiescent
current is further reduced to just 3µA. Figure 2 shows
the s ta nd a rd a p p lic a tion c irc uit for the
MAX1700/MAX1701.
_______________De t a ile d De s c rip t io n
The MAX1700/MAX1701 are highly efficient, low-noise
power supplies for portable RF and data acquisition
instruments. The MAX1700 combines a boost switching
regulator, N-channel power MOSFET, P-channel syn-
chronous rectifier, precision reference, and shutdown
control. The MAX1701 contains all of the MAX1700 fea-
tures plus a versatile gain amplifier, POK output, and a
low-b a tte ry c omp a ra tor (Fig ure 1). The MAX1700/
MAX1701 c ome in a 16-p in QSOP pa c ka ge , whic h
occupies no more space than an 8-pin SO.
Additional features include synchronous rectification for
high efficiency and improved battery life, a POK output,
and an uncommitted comparator for low-battery detec-
tion (MAX1701). A CLK input allows frequency synchro-
nization to reduce interference. Dual shutdown controls
allow shutdown using a momentary pushbutton switch
and microprocessor control (MAX1701).
The switching DC-DC converter boosts a 1- to 3-cell
input to an adjustable output between 2.5V and 5.5V.
The MAX1700/MAX1701 start from a low 1.1V input and
remain operational down to 0.7V.
These devices are optimized for use in cellular phones
and other applications requiring low noise during full-
_______________________________________________________________________________________
9
1 -Ce ll t o 3 -Ce ll, Hig h -P o w e r (1 A),
Lo w -No is e , S t e p -Up DC-DC Co n ve rt e rs
0.7V TO 5.5V
POUT
P
22µF
L1 10µH
MBR0520L
FB
REF
LX
OUTPUT
R
S
Q
LX
MAX1700
MAX1701
CLK/SEL
OUT
D1
2 x
100µF
N
POUT
10Ω
ONA
ONB
0.22µF
OUT
FB
0.22µF
R1
PGND
1.3A CURRENT
LIMIT
REF
GND
ADJUSTABLE
R2
FIXED
OUTPUT
(GND)
PGND
0.22µF
OSC
/MAX701
Figure 2. Fixed or Adjustable Output (PWM mode).
Figure 3. Simplified PWM Controller Block Diagram
the outp ut filte r c a p a c itor a nd loa d . As the e ne rg y
stored in the inductor is depleted, the current ramps
down and the output diode and synchronous rectifier
turn off. Voltage across the load is regulated using
either low-noise PWM or low-power operation, depend-
ing on the CLK/SEL pin setting (Table 2).
Table 1. Typical Available Output Current
NUMBER
INPUT
OUTPUT
OUTPUT
OF CELLS VOLTAGE (V) VOLTAGE (V) CURRENT (mA)
1 NiCd/NiMH
2 NiCd/NiMH
2 NiCd/NiMH
1.2
2.4
2.4
3.3
3.3
5.0
300
750
525
Low-Noise PWM Operation
When CLK/SEL is pulled high, the MAX1700/MAX1701
op e ra te in a hig he r p owe r, low-nois e p uls e -wid th-
modulation (PWM) mode. During PWM operation, they
switch at a constant frequency (300kHz) and then mod-
ulate the MOSFET switch pulse width to control the
power transferred per cycle and regulate the voltage
across the load. In PWM mode the devices can output
up to 800mA. Switching harmonics generated by fixed-
frequency operation are consistent and easily filtered.
See the Noise Spectrum Plot in the Typical Operating
Characteristics.
3 NiCd/NiMH
or 1 Li-Ion
3.6
5.0
850
Table 2. Selecting the Operating Mode
CLK/SEL
MODE
FEATURES
0
Low Power
Low supply current
Low noise,
high output current
1
PWM
External Clock
(200kHz to 400kHz)
Synchronized
PWM
Low noise,
high output current
During PWM operation, each rising edge of the internal
clock sets a flip-flop, which turns on the N-channel
MOSFET switch (Figure 3). The switch is turned off
when the sum of the voltage-error, slope compensation,
and current-feedback signals trips a multi-input com-
parator and resets the flip-flop; the switch remains off
for the rest of the cycle. When a change occurs in the
output-voltage error signal into the comparator, it shifts
the level to which the inductor current is allowed to
ramp during each cycle and modulates the MOSFET
switch pulse width. A second comparator enforces an
inductor current limit of 1.6A max.
S t e p -Up Co n ve rt e r
The step-up switching DC-DC converter generates an
adjustable output from 2.5V to 5.5V. During the first part
of each cycle, the internal N-channel MOSFET switch is
turned on. This allows current to ramp up in the induc-
tor and store energy in a magnetic field. During the
second part of each cycle, when the MOSFET is turned
off, the voltage across the inductor reverses and forces
current through the diode and synchronous rectifier to
10 ______________________________________________________________________________________
1 -Ce ll t o 3 -Ce ll, Hig h -P o w e r (1 A),
Lo w -No is e , S t e p -Up DC-DC Co n ve rt e rs
/MAX701
rectifier current has ramped down to 70mA. This forces
operation with a discontinuous inductor current.
LOGIC HIGH
Q
Q
D
POUT
Synchronous Rectifier
The MAX1700/MAX1701 feature an internal 250mΩ, P-
channel synchronous rectifier to enhance efficiency.
Sync hronous re c tific a tion provide s a 5% e ffic ie nc y
improvement over similar nonsynchronous boost regu-
la tors . In PWM mod e , the s ync hronous re c tifie r is
turned on during the second half of each switching
cycle. In low-power mode, an internal comparator turns
on the synchronous rectifier when the voltage at LX
exceeds the boost-regulator output and then turns it off
when the inductor current drops below 70mA.
R
P
ERROR
COMPARATOR
LX
FB
N
S
Q
REF
R
400mA
CURRENT
LIMIT
Lo w -Vo lt a g e S t a rt -Up Os c illa t o r
The MAX1700/MAX1701 us e a CMOS, low-volta g e
start-up oscillator for a 1.1V guaranteed minimum start-
up input voltage at +25°C. On start-up, the low-voltage
oscillator switches the N-channel MOSFET until the out-
put voltage reaches 2.15V. Above this level, the normal
boost-converter feedback and control circuitry take
over. Once the device is in regulation, it can operate
down to a 0.7V input since internal power for the IC is
bootstrapped from the output using the OUT pin. Do
not apply full load until the output exceeds 2.4V.
PGND
Figure 4. Controller Block Diagram in Low-Power PFM Mode
Synchronized PWM Operation
By a p p lying a n e xte rna l c loc k to CLK/SEL, the
MAX1700/MAX1701 can also be synchronized in PWM
mode to a frequency between 200kHz and 400kHz.
This allows the user to set the harmonics to avoid IF
bands in wireless applications. The synchronous rectifi-
er is also active during synchronized PWM operation.
Table 3. On/Off Logic Control
ONA
ONB
Status
On
Low-Power PFM Operation
Pulling CLK/SEL low places the MAX1700/MAX1701 in
a low-power mode. During low-power mode, PFM oper-
ation regulates the output voltage by transferring a
fixed amount of energy during each cycle and then
mod ula ting the s witc hing fre q ue nc y to c ontrol the
power delivered to the output. The devices switch only
as needed to service the load, resulting in the highest
possible efficiency at light loads. Output current capa-
bility in PFM mode is 100mA. The output voltage is typi-
cally 1% higher than the output voltage in PWM mode.
0
0
1
1
0
1
0
1
Off
On
On
S h u t d o w n
The MAX1700/MAX1701 shut down to reduce quies-
cent current to typically 3µA. During shutdown, the ref-
erence, low-battery comparator, gain block, and all
feedback and control circuitry are off. The boost con-
verter’s output drops to one Schottky diode drop below
the input.
During PFM operation, the error comparator detects the
output voltage falling out of regulation and sets a flip-
flop, turning on the N-channel MOSFET switch (Figure
4). When the inductor current ramps to the PFM mode
current limit (400mA typical) and stores a fixed amount
of energy, the current-sense comparator resets a flip-
flop. The flip-flop turns off the N-channel switch and
turns on the P-channel synchronous rectifier. A second
flip-flop, previously reset by the switch’s “on” signal,
inhibits the error comparator from initiating another
cycle until the energy stored in the inductor is trans-
ferred to the output filter capacitor and the synchronous
Table 3 shows the control logic with ONA and ONB.
Both inp uts ha ve trip p oints ne a r 0.5V
with
OUT
0.15V
hysteresis.
OUT
Lo w -Ba t t e ry Co m p a ra t o r (MAX1 7 0 1 )
The internal low-battery comparator has uncommitted
inputs and an open-drain output (LBO) capable of sink-
ing 1mA. To use it as a low-battery-detection compara-
tor, c onne c t the LBN inp ut to the re fe re nc e , a nd
connect the LBP input to an external resistor divider
______________________________________________________________________________________ 11
1 -Ce ll t o 3 -Ce ll, Hig h -P o w e r (1 A),
Lo w -No is e , S t e p -Up DC-DC Co n ve rt e rs
0.7V TO 5.5V
POUT
REF
L1
D1
MAX1701
0.22µF
R5
R6
LX
MAX1701
LBO
LBP
POUT
LBN
CLK/SEL
10Ω
ONA
ONB
10k
OUT
0.22µF
GND
BATTERY
VOLTAGE
ARBITRARY
VOLTAGE
R3
R4
LBP
POK
LBO
AO
VOLTAGE MONITOR
LOW-BATTERY MONITOR
LBN
REF
GND PGND FB
R5
ARBITRARY VOLTAGE MONITOR
Figure 7. Detecting Battery Voltages Below 1.25V (MAX1701)
AIN
R6
10Ω
OUTPUT
C5
P
/MAX701
Figure 5. Detecting Battery Voltage Above 1.25V
C3
0.22µF
POUT
OUT
R3
R4
270k
LBN
C4
POUT
OUT
MAX1701
LBO
LBP
REF
MAX1701
R3
R4
LBO
LBN
REF
LBP
GND
0.22µF
GND
0.22µF
Figure 8. Using the Low-Battery Comparator for Load Control
During Start-Up
and LBN and connect the battery to the LBP input
through a 10kΩ current-limiting resistor (Figure 7). The
equation for setting the resistors for the low-battery
threshold is then as follows:
Figure 6. Using the Low-Battery Comparator to Sense the
Output Voltage (MAX1701)
between the positive battery terminal and GND (Figure
5). The resistor values are then calculated as follows:
R5 = R6(V /V
-1)
REF LBP
R3 = R4(V /V
-1)
TH LBN
where V
is the desired voltage threshold. In Figures
LBP
5, 6, and 7, LBO goes low for a low-voltage input. The
low-battery comparator can be used to check the out-
where V is the desired input voltage trip threshold
TH
and V
= V
= 1.25V. Since the input bias current
LBN
REF
put voltage or to control the load directly on P
dur-
OUT
into LBP is less than 20nA, R4 can be a large value
(such as 270kΩ or less) without sacrificing accuracy.
The inputs have a common-mode input range from
0.5V to 1.5V and an input-referred hysteresis of 15mV.
ing start-up (Figure 8). Use the following equation to set
the resistor values:
R3 = R4(V
/V
- 1)
OUTTH LBP
The low-battery comparator can also be used to moni-
tor the output voltage, as shown in Figure 6.
where V
is the desired output-voltage trip point
is connected to the reference or 1.25V.
OUTTH
and V
LBP
To set the low-battery threshold to a voltage below the
1.25V reference, insert a resistor divider between REF
12 ______________________________________________________________________________________
1 -Ce ll t o 3 -Ce ll, Hig h -P o w e r (1 A),
Lo w -No is e , S t e p -Up DC-DC Co n ve rt e rs
/MAX701
Re fe re n c e
The MAX1700/MAX1701 have an internal 1.250V, 1%
bandgap reference. Connect a 0.22µF bypass capaci-
tor to GND within 0.2in. (5mm) of the REF pin. REF can
source up to 50µA of external load current.
Ga in Blo c k (MAX1 7 0 1 )
The MAX1701’s gain block can function as a third com-
parator or can be used to build a linear regulator using
an external P-channel MOSFET pass device. The gain-
block output is a single-stage transconductance ampli-
fie r tha t d rive s a n op e n-d ra in N-c ha nne l MOSFET.
Figure 9 shows the gain block used in a linear regula-
tor. The output of an external P-channel pass element is
compared to the internal reference. The difference is
amplified and used to drive the gate of the pass ele-
ment. Use a logic-level PFET such as the Fairchild
P o w e r-OK (MAX1 7 0 1 )
The MAX1701 features a power-good comparator. This
comparator’s open-drain output (POK) is pulled low
when the output voltage falls to 10% below the regula-
tion point.
NDS336P (R
= 270mΩ). If the PFET R
is
DS(ON)
DS(ON)
IN
le s s tha n 250mΩ, the line a r re g ula tor outp ut filte r
capacitance may need to be increased to above 47µF.
P
__________________De s ig n P ro c e d u re
LX
S e t t in g t h e Ou t p u t Vo lt a g e s
Set the output voltage between 2.5V and 5.5V by con-
necting a resistor voltage-divider to FB from OUT to
GND, as shown in Figure 2. The resistor values are then
as follows:
20k
2x
100µF
MAX1701
47µF
AO
N
R1 = R2 (V /V - 1)
OUT FB
R5
where V , the boost-regulator feedback setpoint, is
FB
AIN
REF
1.23V. Since the input bias current into FB is less than
20nA, R2 can have a large value (such as 270kΩ or
less) without sacrificing accuracy. Connect the resistor
voltage-divider as close to the IC as possible, within
0.2in. (5mm) of the FB pin.
R6
Figure 9. Using Gain Block as a Linear Regulator
Table 4. Component Suppliers
In d u c t o r S e le c t io n
The MAX1700/MAX1701’s high switching frequency
allows the use of a small surface-mount inductor. A
10µH inductor should have a saturation-current rating
that exceeds the N-channel switch current limit of 1.6A.
However, it is generally acceptable to bias the inductor
current into saturation by as much as 20%, although
this will slightly reduce efficiency. For high efficiency,
choose an inductor with a high-frequency core material
(such as ferrite) to reduce core losses. To minimize
radiated noise, use a toroid, pot core, or shielded bob-
bin inductor. Connect the inductor from the battery to
the LX pin as close to the IC as possible. See Table 4
for a list of component suppliers and Table 5 for sug-
gested components.
SUPPLIER
PHONE
FAX
USA: (803) 946-0690
(800) 282-4975
(803) 626-3123
AVX
Coilcraft
Matsuo
USA: (847) 639-6400
USA: (714) 969-2491
USA: (602) 303-5454
(847) 639-1469
(714) 960-6492
(602) 994-6430
Motorola
USA: (619) 661-6835
Japan: 81-7-2070-6306
(619) 661-1055
81-7-2070-1174
Sanyo
USA: (847) 956-0666
Japan: 81-3-3607-5111
(847) 956-0702
81-3-3607-5144
Sumida
Table 5. Component Selection Guide
PRODUCTION
INDUCTORS
CAPACITORS
Matsuo 267 series
Sprague 595D series
AVX TPS series
DIODES
Sumida CDR63B, CD73, CDR73B, CD74B series
Coilcraft DO1608, DO3308, DT3316 series
Surface Mount
Motorola MBR0520L
Sanyo OS-CON series
Nichicon PL series
Through Hole
Sumida RCH654 series
1N5817
______________________________________________________________________________________ 13
1 -Ce ll t o 3 -Ce ll, Hig h -P o w e r (1 A),
Lo w -No is e , S t e p -Up DC-DC Co n ve rt e rs
µC
LX
POUT
270k
MAX1701
V
DD
OUT
ONB
ONA
ON/OFF
MAX1700
MAX8865/MAX8866 DUAL OR
MAX8863/MAX8864 SINGLE
LOW-DROPOUT LINEAR REGULATORS
I/O
I/O
PA
0.1µF
270k
µC
RADIO
Figure 10. Momentary Pushbutton On/Off Switch
Figure 11. Typical Phone Application
/MAX701
exceed the ripple current ratings of tantalum capaci-
tors . Avoid mos t a luminum-e le c trolytic c a p a c itors ,
since their ESR is often too high.
Ou t p u t Dio d e
Use a Schottky diode, such as a 1N5817, MBR0520L, or
equivalent. The Schottky diode carries current during
start-up, and in PFM mode after the synchronous rectifier
turns off. Thus, its current rating only needs to be 500mA.
Byp a s s Ca p a c it o rs
Two ceramic bypass capacitors are required for proper
operation. Bypass REF with a 0.22µF capacitor to GND.
Also connect a 0.22µF ceramic capacitor from OUT to
GND. Each should be placed as close to their respec-
tive pins as possible, within 0.2in. (5mm) of the DC-DC
converter IC. See Table 4 for suggested suppliers.
Connect the diode between LX and P
as close to the
OUT
IC as possible. Do not use ordinary rectifier diodes since
slow switching speeds and long reverse recovery times
will compromise efficiency and load regulation.
In p u t a n d Ou t p u t Filt e r Ca p a c it o rs
Choose input and output filter capacitors that will ser-
vice the input and output peak currents with accept-
a b le volta g e rip p le . Choos e inp ut c a p a c itors with
working voltage ratings over the maximum input volt-
age, and output capacitors with working voltage ratings
higher than the output.
__________Ap p lic a t io n s In fo rm a t io n
P u s h -On /P u s h -Off Co n t ro l
A momentary pushbutton switch can be used to turn
the MAX1700/MAX1701 on and off. In Figure 10, ONA
is pulled low and ONB is pulled high when the part is
off. When the momentary switch is pressed, ONB is
pulled low and the regulator turns on. The switch must
be pressed long enough for the microcontroller to exit
reset (200ms) and drive ONA high. A small capacitor is
added to help debounce the switch. The controller
issues a logic high to ONA, which holds the part on
regardless of the switch state. To turn the regulator off,
press the switch again, allowing the controller to read
the switch status and pull ONA low. When the switch is
released, ONB is pulled high.
For full output, two 100µF, 100mΩ, low-ESR tantalum out-
put filter capacitors are recommended. For loads below
250mA, a single 100µF output capacitor will suffice. The
input filter capacitor (CIN) reduces peak currents drawn
from the input source and reduces input switching noise.
The input voltage source impedance determines the
required size of the input capacitor. When operating
directly from one or two NiCd cells placed close to the
MAX1700/MAX1701, use a 22µF, low-ESR input filter
capacitor. When operating from a power source placed
farther away, or from higher impedance batteries such as
alkaline or lithium cells, use one or two 100µF, 100mΩ,
low-ESR tantalum capacitors.
Us e in a Typ ic a l Wire le s s
P h o n e Ap p lic a t io n
The MAX1700/MAX1701 are ideal for use in digital
cordless and PCS phones. The power amplifier (PA) is
connected directly to the boost-converter output for
maximum voltage swing (Figure 11). Low-dropout linear
regulators are used for post-regulation to generate
Sanyo OS-CON and Panasonic SP/CB-series ceramic
capacitors offer the lowest ESR. Low-ESR tantalum
capacitors are a good choice and generally offer a
good tradeoff between price and performance. Do not
14 ______________________________________________________________________________________
1 -Ce ll t o 3 -Ce ll, Hig h -P o w e r (1 A),
Lo w -No is e , S t e p -Up DC-DC Co n ve rt e rs
/MAX701
low-noise power for DSP, control, and RF circuitry.
S o ft -S t a rt
To implement soft-start, set CLK/SEL low on power-up;
this forces low-power operation and reduces the peak
switching current to 550mA max. Once the circuit is in
re g ula tion a nd s ta rt-up tra ns ie nts ha ve s e ttle d ,
CLK/SEL can be set high for full-power operation.
Typically, RF phones spend most of their life in standby
mode with only short periods in transmit/receive mode.
During s ta nd b y, ma ximize b a tte ry life b y s e tting
CLK/SEL = 0; this places the IC in low-power mode (for
the lowest quiescent power consumption).
In t e rm it t e n t S u p p ly/Ba t t e ry Co n n e c t io n s
Whe n b oos ting a n inp ut s up p ly c onne c te d with a
mechanical switch, or a battery connected with spring
contacts, input power may sometimes be intermittent
as a result of contact bounce. When operating in PFM
mode with input voltages greater than 2.5V, restarting
after such dropouts may initiate high current pulses that
interfere with the MAX1700/MAX1701 internal MOSFET
switch control. If contact or switch bounce is anticipat-
ed in the design, use one of the following solutions.
De s ig n in g a P C Bo a rd
High switching frequencies and large peak currents
make PC board layout an important part of design.
Poor design can cause excessive EMI and ground-
bounce, both of which can cause instability or regula-
tion e rrors b y c orrup ting the volta g e a nd c urre nt
feedback signals.
Power components (such as the inductor, converter IC,
filter capacitors, and output diode) should be placed as
close together as possible, and their traces should be
ke p t s hort, d ire c t, a nd wid e . A s e p a ra te low-nois e
g round p la ne c onta ining the re fe re nc e a nd s ig na l
g round s s hould only c onne c t to the p owe r-g round
plane at one point. This minimizes the effect of power-
ground currents on the part. Consult the MAX1701 EV
kit manual for a layout example.
1) Connect a capacitor (C
) from ONB to V , a 1MΩ
IN
ONB
resistor (R ) from ONB to GND, and tie ONA to GND
ONB
(Figure 12). This RC network differentiates fast input
edges at V and momentarily holds the IC off until V
IN
IN
settles. The appropriate value of C
is 10-5 times the
ONB
total output filter capacitance (C
), so a C
OUT
of
OUT
200µF results in C
= 2nF.
ONB
On multilayer boards, do not connect the ground pins
of the power components using vias through an internal
ground plane. Instead, place them close together and
route them in a star-ground configuration using compo-
nent-side copper. Then use vias to connect the star
ground to the internal ground plane.
2) Us e the s ys te m mic roc ontrolle r to hold the
MAX1700/MAX1701 in shut down from the time when
power is applied (or reapplied) until the output capaci-
tance (C
) has charged to at least the input voltage.
OUT
Power-on reset times of tens of milliseconds accom-
plish this.
Keep the voltage feedback network very close to the
IC, within 0.2in. (5mm) of the FB p ins . Ke e p nois y
traces, such as from the LX pin, away from the voltage
fe e d b a c k ne tworks . Se p a ra te the m with g round e d
copper. Consult the MAX1700 evaluation kit for a full
PC board example.
3) Ensure that the IC operates, or at least powers up, in
PWM mode (CLK/SEL = high). Activate PFM mode only
after the V
has settled and all of the system’s power-
OUT
on reset flags are cleared.
P in Co n fig u ra t io n s (c o n t in u e d )
TOP VIEW
13
14
LX
C
2nF
ONB
LBP
LBN
1
2
3
4
5
6
7
8
16 LBO
15 POUT
14 OUT
13 LX
C
200µF
OUT
7
8
ONB
ONA
OUT
REF
R
ONB
1M
MAX1700
MAX1701
CLK/SEL
GND
MAX1701
15
POUT
12 PGND
11 FB
POK
ONB
10 AIN
ONA
9 AO
Figure 12. Connecting C
Battery-Contact Bounce Is Anticipated
and R
when Switch or
ONB
ONB
QSOP
______________________________________________________________________________________ 15
1 -Ce ll t o 3 -Ce ll, Hig h -P o w e r (1 A),
Lo w -No is e , S t e p -Up DC-DC Co n ve rt e rs
Ch ip In fo rm a t io n
TRANSISTOR COUNT: 531
SUBSTRATE CONNECTED TO GND
________________________________________________________P a c k a g e In fo rm a t io n
/MAX701
16 ______________________________________________________________________________________
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