Electronic Components Datasheet Search
  English  ▼
ALLDATASHEET.COM

X  

MAX775EPA Datasheet(PDF) 11 Page - Maxim Integrated Products

Part # MAX775EPA
Description  -5V/-12V/-15V or Adjustable, High-Efficiency, Low IQ Inverting DC-to-DC Controllers
Download  16 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  MAXIM [Maxim Integrated Products]
Direct Link  https://www.maximintegrated.com/en.html
Logo MAXIM - Maxim Integrated Products

MAX775EPA Datasheet(HTML) 11 Page - Maxim Integrated Products

Back Button MAX775EPA Datasheet HTML 7Page - Maxim Integrated Products MAX775EPA Datasheet HTML 8Page - Maxim Integrated Products MAX775EPA Datasheet HTML 9Page - Maxim Integrated Products MAX775EPA Datasheet HTML 10Page - Maxim Integrated Products MAX775EPA Datasheet HTML 11Page - Maxim Integrated Products MAX775EPA Datasheet HTML 12Page - Maxim Integrated Products MAX775EPA Datasheet HTML 13Page - Maxim Integrated Products MAX775EPA Datasheet HTML 14Page - Maxim Integrated Products MAX775EPA Datasheet HTML 15Page - Maxim Integrated Products Next Button
Zoom Inzoom in Zoom Outzoom out
 11 / 16 page
background image
connected to the output voltage (-5V, -12V, -15V). In
nonbootstrapped operation, OUT is connected to
ground, and EXT now swings from V+ to ground.
At high input-to-output differentials, it may be neces-
sary to use nonbootstrapped mode to avoid the 21V V+
to VOUT maximum rating. Also, observe the VGS maxi-
mum rating of the external transistor. At intermediate
voltages and currents, the advantages of bootstrapped
vs. nonbootstrapped operation are slight. When input
voltages are less than about 4V, always use the boot-
strapped circuit.
Shutdown and Quiescent Current
The MAX774/MAX775/MAX776 are designed to save
power in battery-powered applications. A TTL/CMOS
logic-level shutdown input (SHDN) has been provided
for the lowest-power applications. When shut down
(SHDN = V+), most internal bias current sources and
the reference are turned off so that less than 5µA of
current is drawn.
In normal operation, the quiescent current will be less
than 100µA. However, this current is measured by forc-
ing the external switch transistor off. Even with no load,
in an actual application, additional current will be
drawn to supply the feedback resistors’ and the diode’s
and capacitor’s leakage current. Under no-load condi-
tions, you should see a short current pulse at half the
peak current approximately every 100ms (the exact
period depends on actual circuit leakages).
EXT Drive Voltages
EXT swings from OUT to V+ and provides the drive out-
put for an external power MOSFET. When using the on-
chip feedback resistors for the preset output voltages,
the voltage at OUT equals the output voltage. When
using external feedback resistors, OUT may be tied to
GND or some other potential between VOUT and GND.
Always observe the V+ to OUT absolute maximum rat-
ing of 21V. For V+ to output differentials greater than
21V, OUT must be tied to a potential more positive than
the output and, therefore, the output voltage must be
set with an external resistor divider.
In nonbootstrapped operation with low input voltages
(<4V), tie OUT to a negative voltage to fully enhance the
external MOSFET. Accomplish this by creating an inter-
mediate voltage for VOUT with a zener diode (Figure 5).
__________________Design Procedure
Setting the Output Voltage
The MAX774/MAX775/MAX776 are preset for -5V, -12V,
and -15V output voltages, respectively; however, they
may also be adjusted to other values with an external
voltage divider. For the preset output voltage, connect
FB to REF and connect OUT to the output (Figure 3). In
this case, the output voltage is sensed by OUT.
For an adjustable output (Figures 3 and 4), connect an
external resistor divider from the output voltage to FB,
and from FB to REF. In this case, the divided-down out-
put voltage is sensed via the FB pin.
There are three reasons to use the external resistor divider:
1) An output voltage other than a preset value is
desired.
2) The input-to-output differential exceeds 21V.
3) The output voltage (VOUT to GND) exceeds -15V.
See Figures 3 and 4 for adjustable operation. The
impedance of the feedback network should be low
enough that the input bias current of FB is not a factor.
For best efficiency and precision, allow 10µA to flow
through the network. Calculate (VREF -VFB) / R1 =
10µA. Since VREF = 1.5V and VFB = 0V, R1 becomes
150k
Ω. Then calculate R2 as follows:
R2
VOUT
___ = _______
R1
VREF
(or, VOUT = 10
µA)
______
R2
Choosing an Inductor
Practical inductor values range from 10µH to 50µH.
The maximum inductor value is not particularly critical.
For highest current at high
VOUT to V+ ratios, the
-5V/-12V/-15V or Adjustable, High-Efficiency,
Low IQ Inverting DC-to-DC Controllers
______________________________________________________________________________________
11
Figure 5. Connection Using Zener Diode to Boost Base Drive
R1
MAX774
MAX775
MAX776
OUT
GND
FB
R2
8
2
1
REF
4
0.1
µF
0.1
µF
VOUT
RZ
6V
≤ VZ + VIN ≤ 10V
VOUT – VZ
> IZ
RZ
IZ = ZENER BREAKDOWN CURRENT
VZ = ZENER BREAKDOWN VOLTAGE
VIN = INPUT SUPPLY VOLTAGE


Similar Part No. - MAX775EPA

ManufacturerPart #DatasheetDescription
logo
Maxim Integrated Produc...
MAX775EPA MAXIM-MAX775EPA Datasheet
163Kb / 16P
   -5V/-12V/-15V or Adjustable, High-Efficiency, Low IQ Inverting DC-DC Controllers
Rev 1; 3/94
More results

Similar Description - MAX775EPA

ManufacturerPart #DatasheetDescription
logo
Maxim Integrated Produc...
MAX774 MAXIM-MAX774 Datasheet
163Kb / 16P
   -5V/-12V/-15V or Adjustable, High-Efficiency, Low IQ Inverting DC-DC Controllers
Rev 1; 3/94
MAX770 MAXIM-MAX770 Datasheet
204Kb / 20P
   5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers
Rev 2; 11/96
MAX764 MAXIM-MAX764 Datasheet
132Kb / 12P
   -5V/-12V/-15V or Adjustable, High-Efficiency, Low IQ DC-DC Inverters
Rev 0; 6/94
MAX761 MAXIM-MAX761 Datasheet
122Kb / 12P
   12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Converters
Rev 0; 11/93
MAX1771 MAXIM-MAX1771 Datasheet
195Kb / 16P
   12V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controller
19-0263; Rev 1; 7/95
MAX1649 MAXIM-MAX1649 Datasheet
167Kb / 12P
   5V/3.3V or Adjustable, High-Efficiency, Low-Dropout, Step-Down DC-DC Controllers
19-0305; Rev 2; 9/95
MAX1649 MAXIM-MAX1649_09 Datasheet
223Kb / 12P
   5V/3.3V or Adjustable, High-Efficiency, Low-Dropout, Step-Down DC-DC Controllers
Rev 3; 3/09
MAX1626 MAXIM-MAX1626 Datasheet
185Kb / 16P
   5V/3.3V or Adjustable, 100% Duty-Cycle, High-Efficiency, Step-Down DC-DC Controllers
19-1075; Rev 0; 6/96
MAX1626 MAXIM-MAX1626_V01 Datasheet
383Kb / 16P
   5V/3.3V or Adjustable, 100% Duty-Cycle, High-Efficiency, Step-Down DC-DC Controllers
2015
MAX639 MAXIM-MAX639_05 Datasheet
778Kb / 13P
   5V/3.3V/3V/Adjustable, High-Efficiency, Low IQ, Step-Down DC-DC Conver
Rev 4; 7/05
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16


Datasheet Download

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEET.COM
Does ALLDATASHEET help your business so far?  [ DONATE ] 

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Link Exchange   |   Manufacturer List
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com