MAX850 データシートの表示（PDF） - Maxim Integrated
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MAX850 Datasheet PDF : 8 Pages
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Low-Noise, Regulated, Negative
Charge-Pump Power Supplies for GaAsFET Bias
sensitivity and interference. The clock must be a square wave
between 40% and 60% duty cycle. The maximum clock fre-
quency is 250kHz, and the minimum frequency is 50kHz.
Layout and Grounding
Good layout is important, primarily for good noise perfor-
mance.
___________________Chip Topography
C1+
IN
1) Mount all components as close together as possible.
2) Keep traces short to minimize parasitic inductance
and capacitance. This includes connections to FB.
3) Use a ground plane.
C1-
NEGOUT
GND
0.127"
(3.226mm)
Noise and Ripple Measurement
Accurately measuring the output noise and ripple is a chal-
OUT
lenge. Brief differences in ground potential between the
MAX850–MAX853 circuit and the oscilloscope (which result
from the charge pump’s switching action) cause ground
FB (MAX850–852)
CONT (MAX853)
currents in the probe’s wires, inducing sharp voltage spikes.
For best results, measure directly across the output capaci-
tor (C4). Do not use the ground lead of the oscilloscope
SHDN (MAX850/853)
SHDN (MAX851)
OSC (MAX852)
probe; instead, remove the probe’s tip cover and touch the
ground ring on the probe directly to C4’s ground terminal.
0.085"
(2.159mm)
You can also use a Tektronix chassis mount test jack (part
no. 131-0258) to connect your scope probe directly. This
TRANSISTOR COUNT: 164
direct connection gives the most accurate noise and rip- SUBSTRATE CONNECTED TO IN
ple measurement.
________________________________________________________Package Information
EH
INCHES
DIM
MIN MAX
A 0.053 0.069
A1 0.004 0.010
B 0.014 0.019
C 0.007 0.010
D 0.189 0.197
E 0.150 0.157
e
0.050 BSC
H 0.228 0.244
h 0.010 0.020
L 0.016 0.050
α
0˚
8˚
MILLIMETERS
MIN MAX
1.35 1.75
0.10 0.25
0.35 0.49
0.19 0.25
4.80 5.00
3.80 4.00
1.27 BSC
5.80 6.20
0.25 0.50
0.40 1.27
0˚
8˚
21-325A
D
A
h x 45˚
α
0.127mm
0.004in.
e
A1
C
L
B
8-PIN PLASTIC
SMALL-OUTLINE
PACKAGE
8 ______________________________________________________________________________________
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