Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

open drain/collector driver???

Status
Not open for further replies.
X

xczms

Junior Member level 3
Junior Member level 3
Joined
Feb 20, 2004
Messages
31
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Location
hangzhou, china
Activity points
341
drain collector

I'm designing the application platform of the GPRS module MC35i, now I have some problem on the the design of the pin IGH, the electronical description of this pin are as follows:

signal form and level:
RI ≈ 100k, CI ≈ 1nF
VILmax = 0.5V at Imax = -20µA
VOpenmax = 2.3V
ON ~~~|____|~~~ Active Low >100mS

comment:
This signal switches the
mobile ON.
This line must be driven low
by an Open Drain or Open
Collector driver.

could anyone help me with the open drain/collector driver? how to implement it, can you recommend me some chipsets? thank you
 

open drain driver

Just use a BSS138 or similar low treshold voltage mosfet. Put drain in the pin of module, source to gnd, and gate to the controller or whatever you use to control that module. A 0-1-0 pulse on the gate will give desired 1-0-1 pulse to start the module. Just comply with the duration of pulse, as specified in the datasheet. Gate is compatible with both 5v and 3v logic levels.

/pisoiu
 

open drain pin

then could i use the transistor like 9013 ?
 

how open-drain driver work

xczms said:
then could i use the transistor like 9013 ?
Click to expand...

I don't know the parameters of this transistor, but if it is low power and if its treshold voltage (specified in its datasheet) is under the minimum "1" state voltage of your device used to control the module, you can use it. Of course, you can use also a bipolar transistor instead of mosfet, but for this one you have to add a resistor in series with base.

/pisoiu
 

use of open drain

if i use the BSS138, shoud i use the pull-up resistence on the drain pin? and the VOpenmax=2.3v means the high level that ipnut to the module could not be higher than this, right?
 

open drain output

xczms said:
if i use the BSS138, shoud i use the pull-up resistence on the drain pin? and the VOpenmax=2.3v means the high level that ipnut to the module could not be higher than this, right?
Click to expand...

Usually, that resistor is inside modem. Check the datasheet, and if it says that pin is pulled up, do NOT use an external resistor between drain and vcc. If the pin is not internally pulled up (somehow I doubt this), then put 1kohm between drain and vcc. Vopenmax=2.3 means that the voltage on that pin must be under 2,3v to sense the commnd. Use BSS138 and it will work. Hope it is clear now.

/pisoiu
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top