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Section Topics

2308-900-01 Rev. A / July 2008

Section 3: Pulse Current Measurements

Model 2308 Portable Device Battery/Charger Simulator User’s Manual

SENSe[1]:PulseCURrent:SEARch <b>

Applies to battery channel (#1)

SENSe2: PulseCURrent:SEARch <b>

Applies to charger channel (#2)

See

Using FAST, SEARch, and DETect

for detailed usage information.

SENSe[1]: PulseCURrent:DETect <b>

Applies to battery channel (#1)

SENSe2: PulseCURrent:DETect <b>

Applies to charger channel (#2)

See

Using FAST, SEARch, and DETect

for detailed usage information.

SENSe[1]:PulseCURrent:TimeOUT <NRf>

Applies to battery channel (#1)

SENSe2: PulseCURrent: TimeOUT <NRf>

Applies to charger channel (#2)

See

Using FAST, SEARch, and DETect

for detailed usage information on properly setting the

TimeOUT variable.

Using FAST, SEARch, and DETect

Use the

FAST

command to have the quickest response for pulse current measurements triggered

by the measurement commands (for example,

MEASure

READ

or *

TRG)

. Note that when you

use the

FAST

command, there is no indication that the instrument is correctly configured for

detecting pulses until a measurement command is sent. When the trigger level is set, use the

command to retain quick responses to measurement commands and to ensure that the

instrument is configured correctly for detecting pulses. Use the

DETect

command to ensure that

the unit is configured correctly and can read the pulse before sending a measurement command.

Use FAST, SEARch, and DETect to control how background readings are taken. A background
reading is a measurement taken by the power supply between user triggered readings. The
selected function dictates how background readings are taken between user triggered readings.

For pulse current, a background reading involves looking for the pulse and optionally generating a
reading for the user. The various settings of

FAST

, and

DETect

allow the user to fine

tune the function. This enables the function to perform the desired background readings (if any)
between user triggered readings. The default settings (

FAST:OFF

SEARch:ON

, and

DETect:OFF

) allow the pulse current background readings to be taken. If no pulse is present, the

setting of TimeOUT affects how responsive the supply is to bus commands. If a pulse is present,
the search time affects how responsive the supply is to bus commands (refer to

Figure 3-5

Table

3-4

contains the available settings for

FAST

, and

DETect

commands and a description

of the resulting action.

In order to efficiently use

FAST

, and

DETect

for pulse current measurements, the user

must know the approximate period of the expected pulse. TOUT (TimeOUT) specifies the timeout
length for searching for the pulse (default setting is 1 second). When the TOUT value is reached,
“NO PULSE” is displayed (top line of the front-panel display) if default settings for FAST, SEARch,
and DETect are used. See

Table 3-4

for what is shown on the front-panel display if the default

settings are not used. Set the value for TOUT as follows:

TOUT

= search Time + Period

Search Time

= time allowed for detection of a pulse edge

Period

= time between consecutive pulse edges

In other words, the timeout value should be set to allow sufficient time for detection of the pulse if
the edge is just missed. In

Figure 3-5

, (P) is the point to start looking for the pulse. Since the rising

edge was just missed, (D) will be the first detectable rising edge. If the timeout is less than search
time, a pulse trigger time out (due to TOUT) may occur. Therefore, if the period = 0.4 seconds, a
good TOUT value would be 0.5 seconds. A similar method for selecting a TOUT value would be to
use a value equal to 105% of the expected pulse period.