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MAX844ESA+

P1-P3P4-P6P7-P9P10-P10
_______________General Description
The MAX840/MAX843/MAX844 low-noise, inverting
charge-pump power supplies are ideal for biasing
GaAsFETs in cellular telephone transmitter amplifiers.
They operate with inputs down to 2.5V.
The MAX840 offers both a -2V preset output and a -0.5V
to -9.4V adjustable output. The MAX843/MAX844 use
an external positive control voltage to set the negative
output voltage. Input voltage range for all the devices is
2.5V to 10V, and output current is 4mA with V
IN
> 2.7V.
These circuits can operate with small capacitors, as low
as 0.22µF.
An internal linear regulator reduces the MAX840’s out-
put voltage ripple to 1mVp-p. With a well-filtered control
voltage (V
CTRL
), the MAX843/MAX844 also achieve less
than 1mVp-p typical output ripple. Supply current is
750µA, and reduces to less than 1µA in shutdown
(MAX840/MAX843). The MAX844’s unregulated output
is active in shutdown, with the charge pump switching at
20kHz. It provides a low-power LCD supply.
________________________Applications
Cellular Phones
GaAsFET Power Amplifier Modules
Personal Communicators, PDAs
Wireless Data Loggers
Continuously Adjustable GaAsFET Bias
LCD-Bias Contrast Control
Regulated Negative Power Supplies
____________________________Features
♦ Fixed -2V or Adjustable -0.5V to -9.4V Output
at 4mA (MAX840)
♦ 2.5V to 10V Input Voltage Range
♦ Operate with Small Capacitors (as low as 0.22µF)
♦ 1mVp-p Output Voltage Ripple
♦ Charge-Pump Switching Frequency:
100kHz in Normal Operation
20kHz in Shutdown Mode (MAX844)
♦ 1µA Max Logic-Level Shutdown Over Temp.
(MAX840/MAX843)
♦ Small 8-Pin SO Package
MAX840/MAX843/MAX844
Low-Noise, Regulated, -2V GaAsFET Bias
________________________________________________________________
Maxim Integrated Products
1
( ) ARE FOR MAX843/MAX844
1
2
3
4
8
7
6
5
IN
GND
OUT
FB (CONT)
SHDN
NEGOUT
C1-
C1+
MAX840
MAX843
MAX844
SO
TOP VIEW
__________________Pin Configuration
MAX840
FB
OUT
SHDN
NEGOUT
C1-
C1+
IN
GND
V
IN
= 2.5V to 10.0V
(3 CELLS)
0.22µF
V
OUT
= -2.0V
(V
GG
of GaAsFET)
4.7µF
0.22µF
0.22µF
ON/OFF
__________Typical Operating Circuit
19-0388; Rev 1; 3/96
PART
MAX840C/D
MAX840ISA
MAX840ESA -40°C to +85°C
-25°C to +85°C
0°C to +70°C
TEMP. RANGE PIN-PACKAGE
Dice*
8 SO
8 SO
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET
______________Ordering Information
* Dice are specified at T
A
= +25°C only.
MAX843C/D
0°C to +70°C Dice*
MAX843ISA -25°C to +85°C 8 SO
MAX843ESA -40°C to +85°C 8 SO
MAX844C/D
0°C to +70°C Dice*
MAX844ISA -25°C to +85°C 8 SO
MAX844ESA -40°C to +85°C 8 SO
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
MAX840/MAX843/MAX844
Low-Noise, Regulated, -2V GaAsFET Bias
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(Figures 2a and 2c, 2.5V ≤ V
IN
≤ 10V, V
OUT
= -2V, GND = 0V, R
L
= ∞, SHDN = V
IN
, T
A
= T
MIN
to T
MAX
, unless otherwise noted.
Typical values are measured at V
IN
= 3.6V and T
A
= +25°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.
Note 1: The output may be shorted to NEGOUT or GND if the package power dissipation is not exceeded. Typical short-circuit
current from 4V to GND is 40mA.
Supply Voltage, V
IN
to GND ..................................-0.3V to 10.5V
V
NEGOUT
to GND...................................................-10.5V to 0.3V
V
IN
to V
NEGOUT
.........................................................-0.3V to 21V
V
OUT
to GND (Note 1).......................................V
NEGOUT
to 0.3V
V
SHDN
to GND ............................................-0.3V to (V
IN
+ 0.3V)
Continuous Power Dissipation (T
A
= +70°C)
SO (derate 5.88mW/°C above +70°C).........................471mW
Operating Temperature Ranges
MAX84_I_ _A ...................................................-25°C to +85°C
MAX84_E_ _A ..................................................-40°C to +85°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10sec).............................+300°C
C4 = 10µF
V
IN
= 3.6V,
R
L
= ∞ or 500Ω
MAX844, V
IN
≤ 3.6V, SHDN = 0V
MAX844, V
IN
= 10V, SHDN = 0V
MAX840/MAX843, V
IN
= 10V, SHDN = 0V
MAX843/MAX844, V
CONT
= 0V
MAX843/MAX844,
V
CTRL
= 2V
MAX840, V
FB
= 0V
MAX840, V
FB
= -0.5V
MAX840, no load
CONDITIONS
mVp-p1V
OUT
Ripple
mV/mA
28
V
OUT
Load Regulation
38
µA
175 300
I
SHUT
Shutdown Supply Current
940
1
nA±1 ±100I
CONT
CONT Leakage Current
nA±1 ±100I
FB
FB Leakage Current
V-0.516 -0.5 -0.484V
FB
FB Voltage
-2.1 -2.0 -1.9
V2.5 10V
IN
Supply Voltage Range
-0.5 to
(V
IN
- 0.6)
V
OUT
Output Voltage Adjust Range
V
-2.05 -2.0 -1.95
V
OUT
Output Voltage
-2.1 -2.0 -1.9
-2.05 -2.0 -1.95
UNITSMIN TYP MAXSYMBOLPARAMETER
80 100 120
Oscillator Frequency F
OSC
V
IN
= 3.6V,
T
A
= +25°C
14 20 26
kHz
Input High Voltage V
IH
SHDN 2.2 V
V
IN
≥ 2.7V,
I
OUT
= 0mA to 4mA
V
IN
≥ 2.5V,
I
OUT
= 0mA to 3mA
V
IN
≥ 2.5V,
I
OUT
= 0mA to 3mA
V
IN
≥ 2.7V,
I
OUT
= 0mA to 4mA
V
MAX840, V
FB
= 0V
MAX843/MAX844,
V
CTRL
= 2V
Input Low Voltage V
IL
SHDN 0.35 V
Input Current I
IN
SHDN -1 1 µA
Input Capacitance C
IN
SHDN 10 pF
MAX840/MAX843/
MAX844
MAX844, SHDN = 0V
No load, V
IN
≤ 3.6VI
Q
Supply Current µA750 1300
MAX840/MAX843/MAX844
Low-Noise, Regulated, -2V GaAsFET Bias
_______________________________________________________________________________________
3
-2.040
010
OUTPUT VOLTAGE 
vs. OUTPUT CURRENT
-2.050
MAX840-01
OUTPUT CURRENT (mA)
OUTPUT VOLTAGE (V)
6
-2.070
-2.060
24 8
13579
-2.040
OUTPUT VOLTAGE vs. INPUT VOLTAGE
OVER TEMPERATURE
-2.050
-2.045
MAX840-02
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
-2.065
-2.060
-2.055
10624 83579
T
A
= +85°C
T
A
= +25°C
T
A
= -40°C
20
0
10
MAXIMUM OUTPUT CURRENT 
vs. INPUT VOLTAGE
60
40
MAX840-03
INPUT VOLTAGE (V)
MAXIMUM OUTPUT CURRENT (mA)
6
120
100
80
24 83579
V
OUT
< -1.95V
(CIRCUIT OF FIG 2a)
V
OUT
< -1.95V
(CIRCUIT OF FIG 2d)
V
OUT
< 2mVp-p RIPPLE
(CIRCUIT OF FIG 2d)
V
OUT
< 2mVp-p RIPPLE
(CIRCUIT OF FIG 2a)
High-current operation not
recommended for extended
periods of time.
0
10
N0-LOAD SUPPLY CURRENT
vs. INPUT VOLTAGE
2
1
MAX840-05
INPUT VOLTAGE (V)
NO-LOAD SUPPLY CURRENT (mA)
6
5
4
3
24 83579
0
10
NEGOUT CURRENT vs. INPUT VOLTAGE
10
5
MAX840-04
INPUT VOLTAGE (V)
NEGOUT CURRENT (mA)
6
30
25
20
15
24 83579
V
NEGOUT
= 0.9 x V
NEGOUT(NO LOAD)
SHUTDOWN
(MAX844)
0
SUPPLY CURRENT vs. TEMPERATURE
3
2
1
MAX840-06
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
40
7
6
5
4
-40 0 80-20 20 60 100
V
IN
= 10V
V
IN
= 3.6V
0.4
START-UP TIME vs. INPUT VOLTAGE
1.6
1.2
0.8
MAX840-07
INPUT VOLTAGE (V)
START-UP TIME (ms)
6
2.8
2.4
2.0
24 8357910
__________________________________________Typical Operating Characteristics
(Circuit of Figure 2a, V
IN
= 3.6V, T
A
= +25°C, unless otherwise noted.)
P1-P3P4-P6P7-P9P10-P10

MAX844ESA+

Mfr. #:
Buy MAX844ESA+
Manufacturer:
Maxim Integrated
Description:
Switching Voltage Regulators Regulated -2V GaAsFET Bias
Lifecycle:
New from this manufacturer.
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