19-0211; Rev 4; 5/96
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET
3.3V/5V or Adjustable-Output,
Step-Up DC-DC Converters
_______________General Description
The MAX856–MAX859 are high-efficiency, CMOS, stepup, DC-DC switching regulators for small, low input voltage or battery-powered systems. The MAX856/MAX858
accept a positive input voltage between 0.8V and V
OUT
and convert it to a higher, pin-selectable output voltage of
3.3V or 5V. The MAX857/MAX859 adjustable versions
accept 0.8V to 6.0V input voltages and generate higher
adjustable output voltages in the 2.7V to 6.0V range.
Typical efficiencies are greater than 85%. Typical quiescent supply current is 25µA (1µA in shutdown).
The MAX856–MAX859 combine ultra-low quiescent supply
current and high efficiency to give maximum battery life. An
internal MOSFET power transistor permits high switching
frequencies. This benefit, combined with internally set peak
inductor current limits, permits the use of small, low-cost
inductors. The MAX856/MAX857 have a 500mA peak
inductor current limit. The MAX858/MAX859 have a 125mA
peak inductor current limit.
________________________Applications
3.3V to 5V Step-Up Conversion
Palmtop Computers
Portable Data-Collection Equipment
Personal Data Communicators/Computers
Medical Instrumentation
2-Cell & 3-Cell Battery-Operated Equipment
Glucose Meters
__________Typical Operating Circuit
____________________________Features
♦ 0.8V to 6.0V Input Supply Voltage
♦ 0.8V Typ Start-Up Supply Voltage
♦ 85% Efficiency at 100mA
♦ 25µA Quiescent Current
♦ 1µA Shutdown Mode
♦ 125mA and 500mA Switch-Current Limits Permit
Use of Low-Cost Inductors
♦ Up to 500kHz Switching Frequency
♦ ±1.5% Reference Tolerance Over Temperature
♦ Low-Battery Detector (LBI/LBO)
♦ 8-Pin SO and µMAX Packages
______________Ordering Information
PART TEMP. RANGE PIN-PACKAGE
MAX856CSA
MAX856CUA 0°C to +70°C 8 µMAX
MAX856C/D 0°C to +70°C Dice*
MAX856ESA -40°C to +85°C 8 SO
MAX856MJA -55°C to +125°C 8 CERDIP
MAX857CSA
MAX857CUA 0°C to +70°C 8 µMAX
MAX857C/D
MAX857ESA -40°C to +85°C 8 SO
MAX857MJA -55°C to +125°C 8 CERDIP
Ordering Information continued at end of data sheet.
* Dice are tested at TA= +25°C only.
†
Contact factory for availability.
0°C to +70°C 8 SO
†
0°C to +70°C 8 SO
0°C to +70°C Dice*
†
MAX856–MAX859
INPUT
0.8V TO V
ON/OFF
3V/5V SELECT
LOW-BATTERY
DETECTOR
INPUT
OUT
OUTPUT
5V AT 100mA
SHDN
47µH
LX
1N5817
OR
3.3V AT 125mA
68µF
MAX856
3/5
LBI
REF
________________________________________________________________
GND
OUT
LBO
LOW-BATTERY
DETECTOR OUTPUT
__________________Pin Configuration
TOP VIEW
SHDN
3/5
REF
LBO
SHDN
REF
LBO
FB
1
2
MAX856
3
MAX858
4
SO/µMAX
1
2
MAX857
3
MAX859
4
SO/µMAX
Maxim Integrated Products
8
LX
7
GND
6
OUT
5
LBI
8
LX
7
GND
6
OUT
5
LBI
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
3.3V/5V or Adjustable-Output,
Step-Up DC-DC Converters
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (OUT to GND) ...................................-0.3V, +7V
Switch Voltage (LX to GND) .......................................-0.3V, +7V
S—H—D—N–, LBO to GND....................................................-0.3V, +7V
LBI, REF, 3/–5–, FB to GND .........................-0.3V, (V
Reference Current (I
Continuous Power Dissipation (T
SO (derate 5.88mW/°C above +70°C) .........................471mW
µMAX (derate 4.1mW/°C above +70°C) ......................330mW
CERDIP (derate 8.00mW/°C above +70°C) .................640mW
Note 1: Reverse battery current is measured from the
connected backwards. A reverse current of 750mA will not exceed the SO or CERDIP package dissipation limits but, if left
for an extended time (more than ten minutes), may degrade performance.
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.
) ..................................................2.5mA
REF
= +70°C)
A
+ 0.3V)
OUT
Typical Operating Circuit’s
Reverse Battery Current (T
Operating Temperature Ranges
MAX85_C_ _ ......................................................0°C to +70°C
MAX85_E_ _ ....................................................-40°C to +85°C
MAX85_MJA .................................................-55°C to +125°C
Junction Temperature .....................................................+150°C
Storage Temperature Range ............................-65°C to +160°C
Lead Temperature (soldering, 10sec) ............................+300°C
battery input terminal to GND when the battery is
≤ +45°C, Note 1) .................750mA
A
MAX856–MAX859
ELECTRICAL CHARACTERISTICS
(Circuits of Figure 2, VIN= 2.5V, I
= 0mA, TA= T
LOAD
MIN
to T
, unless otherwise noted. Typical values are at TA= +25°C.)
MAX
Output Voltage
Minimum Start-Up
Supply Voltage
Quiescent Supply Current in
3.3V Mode (Note 2)
Shutdown Quiescent Current
(Note 2)
Peak Inductor Current Limit
CONDITIONS
MAX856, 3/–5–= 0V, 0mA ≤ I
MAX856, 3/–5–= 3V, 0mA ≤ I
2V ≤ VIN≤ 3V
I
= 0mA
LOAD
I
= 0mA, 3/–5–= 3V, LBI = 1.5V, V
LOAD
(FB = 1.5V, MAX857/MAX859 only)
Output set for 3.3V, measured at VINin Figure 2, R3 omitted.
S—H—D—N–= 0V, 3/–5–= 3V, LBI = 1.5V, V
(FB = 1.5V, MAX857/MAX859 only)
MAX856/MAX857
MAX858/MAX859
No REF load
3/–5–= 3V, -20µA ≤ REF load ≤ 250µA, C
With falling edge
I
= 2mA
SINK
LBO = 5V
MAX857, V
MAX858, 3/–5–= 0V, 0mA ≤ I
MAX858, 3/–5–= 3V, 0mA ≤ I
MAX859, V
= 5V, 0mA ≤ I
OUT
= 5V, 0mA ≤ I
OUT
OUT
OUT
REF
= 3.47V,
= 3.47V,
LOAD
LOAD
LOAD
LOAD
LOAD
LOAD
= 0.22µF
≤ 100mA
≤ 150mA
≤100mA
≤ 25mA
≤ 35mA
≤ 25mA
MAX85_C
MAX85_E/M
4.80 5.0 5.20
3.17 3.3 3.43
4.80 5.0 5.20
4.80 5.0 5.20
3.17 3.3 3.43
4.80 5.0 5.20
1
15
500
125
UNITSMIN TYP MAXPARAMETER
V
V0.8 1.8
V0.8Minimum Operating Voltage
µA25 60
µA60No Load Battery Current
µA
mA
V1.23 1.25 1.27Reference Voltage
%0.8 2.0Reference-Voltage Regulation
V1.22 1.25 1.28LBI Input Threshold
mV25LBI Input Hysteresis
V0.4LBO Output Voltage Low
µA1LBO Output Leakage Current
2 _______________________________________________________________________________________
3.3V/5V or Adjustable-Output,
Step-Up DC-DC Converters
ELECTRICAL CHARACTERISTICS (continued)
(Circuits of Figure 2, VIN= 2.5V, I
–S—H—D—N–
, 3/–5–Input Voltage Low
S—H—D—N–, 3/–5–Input Voltage High 1.6 V
S—H—D—N–, 3/–5–, FB, LBI Input Current LBI = 1.5V, FB = 1.5V, –S—H—D—N–= 0V or 3V, 3/–5–= 0V or 3V ±100 nA
FB Voltage MAX857/MAX859 1.22 1.25 1.28 V
Output Voltage Range MAX857/MAX859, I
Note 2: Supply current from the 3.3V output is measured with an ammeter between the 3.3V output and OUT pin. This current
correlates directly with actual battery supply current, but is reduced in value according to the step-up ratio and efficiency.
V
= 3.47V to keep the internal switch open when measuring the current into the device.
Note 3: Minimum value is production tested. Maximum value is guaranteed by design and is not production tested.
OUT
= 0mA, TA= T
LOAD
to T
MIN
LOAD
, unless otherwise noted. Typical values are at TA= +25°C.)
MAX
= 0mA (Note 3) 2.7 6.0 V
0.4 V
__________________________________________Typical Operating Characteristics
(Circuits of Figure 2, TA= +25°C, unless otherwise noted.)
MAX858/MAX859
EFFICIENCY vs. OUTPUT CURRENT
V
100
90
80
70
60
50
40
EFFICIENCY (%)
30
20
10
0
0.1
0.010.001
LOAD CURRENT (mA)
OUT
= 3.3V
VIN = 1.5V
1
VIN = 2.5V
VIN = 2.0V
10
100 1000
MAX856-01
100
90
80
70
60
50
40
EFFICIENCY (%)
30
20
10
0
MAX858/MAX859
EFFICIENCY vs. OUTPUT CURRENT
V
= 5V
OUT
VIN = 3.3V
VIN = 2.5V
1
10
100 1000
0.1
0.010.001
LOAD CURRENT (mA)
VIN = 1.5V
MAX856-02
MAX856–MAX859
MAX856/MAX857
EFFICIENCY vs. OUTPUT CURRENT
100
90
80
70
60
50
40
EFFICIENCY (%)
30
20
10
0
0.1
0.010.001
LOAD CURRENT (mA)
V
OUT
= 5V
VIN = 2.0V
1
VIN = 3.3V
10
VIN = 1.5V
100 1000
MAX856-03
100
90
80
70
60
50
40
EFFICIENCY (%)
30
20
10
0
MAX856/MAX857
EFFICIENCY vs. OUTPUT CURRENT
V
= 3.3V
OUT
VIN = 2.5V
VIN = 1.5V
VIN = 2.0V
0.1
0.010.001
LOAD CURRENT (mA)
1
10
100 1000
MAX856-04
_______________________________________________________________________________________
3
3.3V/5V or Adjustable-Output,
Step-Up DC-DC Converters
_____________________________Typical Operating Characteristics (continued)
(Circuits of Figure 2, TA= +25°C, unless otherwise noted.)
REFERENCE VOLTAGE vs. CURRENT
10
9
8
7
6
5
4
3
LOAD REGULATION (mV)
REF
2
V
MAX856–MAX859
1
0
0
50 150 250
REFERENCE LOAD CURRENT (µA)
1.6
1.4
1.2
1.0
0.8
0.6
0.4
QUIESCENT CURRENT (mA)
0.2
TA = -40°C
0
1.5
2.0
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
SHUTDOWN CURRENT (µA)
0.2
TA = -40°C
0.1
0
2.0
1.5
100 200
QUIESCENT CURRENT
vs. INPUT VOLTAGE
SEE NOTE 2
IN THE ELECTRICAL
CHARACTERISTICS
2.5 3.0
INPUT VOLTAGE (V)
SHUTDOWN CURRENT
vs. INPUT VOLTAGE
TA = +85°C
TA = +25°C
2.5 3.0
INPUT VOLTAGE (V)
TA = +85°C
3.5
3.5
4.0
4.0
400
350
MAX856-05
300
250
200
150
100
QUIESCENT CURRENT (µA)
50
0
1.5
1.15
MAX856-10
1.10
1.05
1.00
0.95
0.90
0.85
START-UP INPUT VOLTAGE (V)
0.80
0.75
0.1 10
400
MAX856-11
350
300
250
200
150
LOAD CURRENT (mA)
100
50
0
1.0
MAX856/MAX857
NO LOAD BATTERY CURRENT
vs. INPUT VOLTAGE
TA = +85°C
INCLUDES ALL EXTERNAL
COMPONENT LEAKAGES.
CAPACITOR LEAKAGE
DOMINATES AT T
CAPS ARE SPRAGUE 595 D
TA = +25°C
TA = -40°C
MINIMUM START-UP INPUT VOLTAGE
2.5 3.0
2.0
INPUT VOLTAGE (V)
MAX856/MAX857
vs. LOAD CURRENT
1 100
LOAD CURRENT (mA)
MAX856/MAX857
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
V
= 3.3V
OUT
2.01.5 2.5
INPUT VOLTAGE (V)
V
V
= 5.0V
OUT
3.0 3.5 4.0
OUT
= +85°C.
A
3.5
= 5V
V
OUT
= 3.3V
1.6
MAX856-08
1.4
1.2
1.0
0.8
0.6
0.4
QUIESCENT CURRENT (mA)
0.2
4.0
0
1.4
MAX856-06
1.3
1.2
1.1
1.0
START-UP INPUT VOLTAGE (V)
0.9
0.8
100
90
MAX856-13
80
70
60
50
40
30
LOAD CURRENT (mA)
20
10
0
1.5
0.1 10
1.0
4 _______________________________________________________________________________________
MAX858/MAX859
NO LOAD BATTERY CURRENT
vs. INPUT VOLTAGE
= +85°C
T
A
= +25°C
T
A
= -40°C
T
A
MINIMUM START-UP INPUT VOLTAGE
V
OUT
INCLUDES ALL EXTERNAL
COMPONENT LEAKAGES.
CAPACITOR LEAKAGE
DOMINATES AT T
CAPS ARE SPRAGUE 595D
2.5 3.0
2.0
INPUT VOLTAGE (V)
MAX858/MAX859
vs. LOAD CURRENT
V
= 5V
OUT
1 100
LOAD CURRENT (mA)
MAX858/MAX859
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
= 3.3V
V
= 5.0V
OUT
2.0
1.5
2.5 3.0
INPUT VOLTAGE (V)
= +85°C.
A
3.5
3.5
MAX856-09
4.0
MAX856-07
MAX856-12
4.0