19-1600; Rev 1; 6/00
Buck/Boost Regulating
Charge Pump in µMAX
General Description
The MAX1759 is a buck/boost regulating charge pump
that generates a regulated output voltage from a single
lithium-ion (Li+) cell, or two or three NiMH or alkaline
cells for small hand-held portable equipment. The
MAX1759 operates over a wide +1.6V to +5.5V input
voltage range and generates a fixed 3.3V or adjustable
(2.5V to 5.5V) output (Dual Mode
™)
. Maxim’s unique
charge-pump architecture allows the input voltage to be
higher or lower than the regulated output voltage.
Despite its high 1.5MHz operating frequency, the
MAX1759 maintains low 50µA quiescent supply current.
Designed to be an extremely compact buck/boost con-
verter, this device requires only three small ceramic
capacitors to build a complete DC-DC converter capa-
ble of generating a guaranteed 100mA (min) output
current from a +2.5V input. For added flexibility, the
MAX1759 also includes an open-drain power-OK
(POK) output that signals when the output voltage is in
regulation.
The MAX1759 is available in a space-saving 10-pin
µMAX package that is 1.09mm high and half the size of
an 8-pin SO.
Features
o
Regulated Output Voltage (Fixed 3.3V or
Adjustable 2.5V to 5.5V)
o
100mA Guaranteed Output Current
o
+1.6V to +5.5V Input Voltage Range
o
Low 50µA Quiescent Supply Current
o
1µA Shutdown Mode
o
Load Disconnected from Input in Shutdown
o
High 1.5MHz Operating Frequency
o
Uses Small Ceramic Capacitors
o
Short-Circuit Protection and Thermal Shutdown
o
Small 10-Pin µMAX Package
MAX1759
Ordering Information
Applications
Li+ Battery-Powered Applications
Miniature Equipment
Backup Battery Boost Converters
Translators
PART
MAX1759EUB
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
10 µMAX
Typical Operating Circuit
C
X
IN
+1.6V TO +5.5V
C
IN
OUT
3.3V AT 100mA
Pin Configuration
TOP VIEW
CXN
IN
CXP
OUT
POK
1
C
OUT
10
FB
9
OUT
CXP
CXN
PGND
SHDN
IN
IN
2
3
4
5
MAX1759
ON
OFF
SHDN
FB
GND PGND
POK
POWER OK
MAX1759
8
7
6
GND
µMAX
Dual Mode is a trademark of Maxim Integrated Products.
________________________________________________________________
Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Buck/Boost Regulating
Charge Pump in µMAX
MAX1759
ABSOLUTE MAXIMUM RATINGS
IN, OUT, FB, POK,
SHDN
to GND............................-0.3V to +6V
PGND to GND.....................................................................±0.3V
CXN to GND ................................................-0.3V to (V
IN
+ 0.3V)
CXP to GND................-0.3V to (the greater of V
IN
or V
OUT
) + 1V
OUT Short to GND .........................................................Indefinite
Continuous Power Dissipation (T
A
= +70°C)
10-Pin µMAX (derate 5.6mW/°C above +70°C) .........444mW
Operating Temperature Range .......................... -40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) ................................ +300°C
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
(Circuit of Figure 1, V
IN
= V
SHDN
= 2V, FB = PGND = GND, C
IN
= 10µF, C
X
= 0.33µF, C
OUT
= 10µF,
T
A
= 0°C to +85°C,
unless oth-
erwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Input Voltage Range
Input Undervoltage Lockout
Voltage
Output Voltage Adjustment Range
Output Voltage
Maximum Output Current
Transient Load Current
Quiescent Supply Current
Shutdown Supply Current
Leakage Current into OUT in
Shutdown
SHDN
Logic Input Voltage
SHDN
Input Leakage Current
FB Regulation Voltage
FB Input Current
FB Dual-Mode Threshold
POK Trip Voltage
POK Output Low Voltage
POK Leakage Current
Switching Frequency
Output Short-Circuit Current
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
Efficiency
V
IN
= 3.6V, I
LOAD
= 10mA
f
OSC
V
OL
V
IL
V
IH
I
SHDN
V
FB
I
Q
I
Q,SHDN
V
OUT
V
IN
V
UVLO
1.6V
≤
V
IN
≤
5.5V
2V
≤
V
IN
≤
5.5V, 1mA
≤
I
LOAD
≤
50mA
2.5V
≤
V
IN
≤
5.5V, 1mA
≤
I
LOAD
≤
100mA
I
LOAD
≤
100mA (RMS)
V
IN
= V
SHDN
= 4V, V
FB
= 0, stepping down
V
IN
= V
SHDN
= 2V, V
FB
= 0, stepping up
1.6V
≤
V
IN
≤
5.5V, V
SHDN
= 0
V
IN
= 2V, V
OUT
= 3.3V, V
SHDN
= 0
1.6V
≤
V
IN
≤
5.5V
1.6V
≤
V
IN
≤
5.5V
V
SHDN
= 5.5V
V
IN
= 1.65V, V
OUT
= 3.3V
V
FB
= 1.27V
Internal feedback
External feedback
Falling edge at FB
I
SINK
= 0.5mA, V
IN
= 2V
V
POK
= 5.5V, V
FB
= 1.27V
1.6V
≤
V
IN
≤
5.5V, V
FB
= 1V
V
OUT
= 0, 2.5V
≤
V
IN
≤5.5V,
foldback current limit
Rising temperature
1.2
200
1.0
0.7
·
V
IN
-1
1.205
1.235
25
100
100
1.1
5
0.01
1.5
110
160
20
90
1.2
100
0.2
1.8
1
1.265
200
50
1.6
0.6
2.5
3.17
3.17
100
200
50
85
1
1
90
180
5
5
0.25
·
V
IN
3.3
3.3
1.0
5.5
1.4
5.5
3.43
3.43
mA
mA
µA
µA
µA
V
µA
V
nA
mV
mV
V
mV
µA
MHz
mA
°C
°C
%
V
V
V
V
I
LOAD,MAX
2.5V
≤
V
IN
≤
5.5V
2
_______________________________________________________________________________________
Buck/Boost Regulating
Charge Pump in µMAX
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, V
IN
= V
SHDN
= 2V, FB = PGND = GND, C
IN
= 10µF, C
X
= 0.33µF, C
OUT
= 10µF,
T
A
= -40°C to +85°C,
unless oth-
erwise noted.) (Note 1)
PARAMETER
Input Voltage Range
Input Undervoltage Lockout
Voltage
Output Voltage
Output Voltage Adjustment
Range
Maximum Output Current
Quiescent Supply Current
Shutdown Supply Current
Leakage Current into OUT in
Shutdown
SHDN
Input Logic Voltage
SHDN
Input Leakage Current
FB Regulation Voltage
FB Input Bias Current
FB Dual Mode Threshold
POK Trip Voltage
POK Output Low Voltage
POK Leakage Current
Switching Frequency
f
OSC
V
OL
V
IL
V
IH
I
SHDN
V
FB
SYMBOL
V
IN
V
UVLO
V
OUT
2V
≤
V
IN
≤
5.5V, 0
≤
I
LOAD
≤
50mA
2.5V
≤
V
IN
≤
5.5V, 0
≤
I
LOAD
≤
100mA
1.6V
≤
V
IN
≤
5.5V
I
LOAD,MAX
2.5V
≤
V
IN
≤
5.5V
I
Q
I
Q,SHDN
V
IN
= V
SHDN
= 4V, V
FB
= 0
V
IN
= V
SHDN
= 2.5V, V
FB
= 0
1.6V
≤
V
IN
≤
5.5V, V
SHDN
= 0
V
IN
= 2V, V
OUT
= 3.3V, V
SHDN
= 0
1.6V
≤
V
IN
≤
5.5V
1.6V
≤
V
IN
≤
5.5V
V
SHDN
= 5.5V
V
IN
= 1.65V, V
OUT
= 3.3V
V
FB
= 1.27V
Internal feedback
External feedback
Falling edge at FB
I
SINK
= 0.5mA, V
IN
= 2V
V
POK
= 5.5V
1.6V
≤
V
IN
≤
5.5V, V
FB
= 1V
1.1
200
1.0
1.2
100
0.2
1.9
0.7
·
V
IN
-1
1.205
1
1.265
200
40
CONDITIONS
MIN
1.6
0.6
3.15
3.15
2.5
100
90
180
6
5
0.2
·
V
IN
MAX
5.5
1.4
3.45
3.45
5.5
UNITS
V
V
V
V
V
mA
µA
µA
µA
V
V
µA
V
nA
mV
mV
V
mV
µA
MHz
MAX1759
Note 1:
Specifications to -40°C are guaranteed by design and are not production tested.
_______________________________________________________________________________________
3
Buck/Boost Regulating
Charge Pump in µMAX
MAX1759
Typical Operating Characteristics
(Circuit of Figure 1, C
IN
= 10µF, C
X
= 0.33µF, C
OUT
= 10µF, V
OUT
= 3.3V, V
IN
= 2.5V, T
A
= +25°C, unless otherwise noted.)
OUTPUT VOLTAGE RIPPLE
vs. INPUT VOLTAGE
MAX1759 toc01
OUTPUT VOLTAGE vs. LOAD CURRENT
MAX1759 toc02
EFFICIENCY vs. INPUT VOLTAGE
90
80
EFFICIENCY (%)
70
60
50
40
30
I
OUT
= 100mA
I
OUT
= 50mA
I
OUT
= 10mA
MAX1759 toc03
100
OUTPUT VOLTAGE RIPPLE (mV)
I
OUT
= 100mA
3.40
100
80
60
I
OUT
= 50mA
OUTPUT VOLTAGE (V)
3.35
3.30
40
3.25
20
I
OUT
= 10mA
0
1.5
2.5
3.5
INPUT VOLTAGE (V)
4.5
5.5
3.20
0.001
20
10
0
0.01
0.1
1
10
100
1000
1.5
2.5
3.5
INPUT VOLTAGE (V)
4.5
5.5
LOAD CURRENT (mA)
QUIESCENT CURRENT
vs. INPUT VOLTAGE
MAX1759 toc04
MAX1759 toc05
R
LOAD
= 33Ω
3
R
LOAD
= 33Ω
V
IN
= 4.2V
1
QUIESCENT CURRENT (µA)
OUTPUT VOLTAGE (V)
1000
100
2
2
10
1
0.5
1.5
2.5
3.5
INPUT VOLTAGE (V)
NO LOAD
4.5
5.5
1
3
0
0.5
1.5
2.5
3.5
4.5
5.5
5µs/div
CH1: V
OUT
, 20mV/div, AC-COUPLED
CH2: V
CXP
, 5V/div
CH3: V
IN
, 50mV/div, AC-COUPLED
INPUT VOLTAGE (V)
TYPICAL SWITCHING WAVEFORMS
(V
OUT
> V
IN
)
MAX1759 toc07
LOAD-TRANSIENT RESPONSE
(V
OUT
< V
IN
)
MAX1759 toc08
LOAD-TRANSIENT RESPONSE
(V
OUT
> V
IN
)
MAX1759 toc09
R
LOAD
= 33Ω
V
IN
= 2.5V
1
1
1
2
2
3
LOAD STEP: 10mA TO 100mA
V
IN
= 4.2V
5µs/div
CH1: V
OUT
, 20mV/div, AC-COUPLED
CH2: V
CXP
, 5V/div
CH3: V
IN
, 50mV/div, AC-COUPLED
100µs/div
CH1: V
OUT
, 20mV/div, AC-COUPLED
CH2: I
OUT
, 100mA/div
2
LOAD STEP: 10mA TO 100mA
V
IN
= 2.5V
100µs/div
CH1: V
OUT
, 20mV/div, AC-COUPLED
CH2: I
OUT
, 100mA/div
4
_______________________________________________________________________________________
MAX1759 toc06
10,000
STARTUP INPUT VOLTAGE
(V
OUT
< V
IN
)
4
TYPICAL SWITCHING WAVEFORMS
(V
OUT
< V
IN
)
Buck/Boost Regulating
Charge Pump in µMAX
Typical Operating Characteristics (continued)
(Circuit of Figure 1, C
IN
= 10µF, C
X
= 0.33µF, C
OUT
= 10µF, V
OUT
= 3.3V, V
IN
= 2.5V, T
A
= +25°C, unless otherwise noted.)
MAX1759
LINE-TRANSIENT RESPONSE
MAX1759 toc10
TURN-ON/OFF RESPONSE
(V
IN
= 4.2V)
MAX1759 toc11
TURN-ON/OFF RESPONSE
(V
IN
= 2.5V)
R
LOAD
= 33Ω
V
IN
= 2.5V
MAX1759 toc12
R
LOAD
= 33Ω
R
LOAD
= 33Ω
V
IN
= 4.2V
1
1
2
3
-2.5V
100µs/div
CH1: V
OUT
, 20mV/div, AC-COUPLED
CH2: V
IN
, 1V/div, AC-COUPLED
CH1: V
OUT
,1V/div
CH2: I
IN
, 200mA/div
CH3: V
POK
, 5V/div
CH4: V
SHDN
, 5V/div
4
500µs/div
1
2
3
4
500µs/div
CH1: V
OUT
,1V/div
CH2: I
IN
, 200mA/div
CH3: V
POK
, 5V/div
CH4: V
SHDN
, 5V/div
-4.2V
2
Pin Description
PIN
1
NAME
POK
FUNCTION
Open-Drain Power-OK Output. POK is high impedance when output voltage is in regulation. POK sinks current
when V
FB
falls below 1.1V. Connect a 10kΩ to 1MΩ pull-up resistor from POK to V
OUT
for a logic signal.
Ground POK or leave unconnected if not used. POK is high impedance in shutdown.
Shutdown Input. Drive high for normal operation; drive low for shutdown mode. OUT is high impedance in
shutdown.
Input Supply. Connect both pins together and bypass to GND with a ceramic capacitor (see
Capacitor
Selection
section).
Ground. Connect GND to PGND with a short trace.
Power Ground. Charge-pump current flows through this pin.
Negative Terminal of the Charge-Pump Transfer Capacitor
Positive Terminal of the Charge-Pump Transfer Capacitor
Power Output. Bypass to GND with an output filter capacitor.
Dual-Mode Feedback. Connect FB to GND for 3.3V output. Connect to an external resistor divider to adjust
the output voltage from 2.5V to 5.5V.
2
SHDN
3, 4
5
6
7
8
9
10
IN
GND
PGND
CXN
CXP
OUT
FB
_______________________________________________________________________________________
5
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