E7802 SEMTECH [Semtech Corporation], E7802 Datasheet - Page 5

• Manufacturer Part Number: E7802
• Description: Low Cost, Dual-Channel, 15V Pin Electronics Driver/Window Comparator
• Manufacturer: SEMTECH [Semtech Corporation]

For applications that require operation outside the valid
SCP operating zone, the user can use the SCP to check
for any short circuit occurrence down the line and protect
the driver from over-current damage before running it at
the desired operating conditions. Refer to the following
procedure:
1.
2.
3.
4.
5.
TEST AND MEASUREMENT PRODUCTS
Circuit Description (continued)
©
16
14
12
10
8
6
4
2
0
2008 Semtech Corp. , Rev. 5, 3/7/08
0
While the driver is in HiZ (EN=0), enable short-circuit
protection (SCP*=0)
Set VH to the maximum programmable voltage in the
system, switch DATA to Logic “1” and toggle the EN
pin from Logic “0” to “Logic “1”.
After the driver is enabled, wait approximately 2 µs
and monitor all INT* pins in the system to determine
if there is any short circuit occurrence.
If the INT* signal remains high, no short circuit
condition is detected. If the INT* signal becomes
low (active), this indicates a short circuit condition
has occurred in one or more channels in the system.
Determine the shorted channel(s) by checking the
comparator outputs (QH=0, QL=0). Remove the fault
condition in each channel respectively and reset those
driver(s)
Repeat Steps 3 through 4 with minimum programmable
VL in the system and switch DATA to Logic “0”.
Operating Zone
Valid SCP
5
10
Short Circuit Protection Operating Zone
15
Figure 2.
20
Freq (MHz)
25
30
35
40
45
Tj=100C
Tj=65C
Tj=40C
Tj=25C
50
6.
NOTE: If short circuit protection is used outside of the valid
SCP operating zone, false SCP triggers can occur which will
disable the driver output, DOUT.
Window Comparator
Each channel of the E7802 features two comparators
connected in a window comparator configuration. CVH
and CVL are high impedance analog voltage inputs that
establish the upper and lower thresholds for the window
comparator. CVH should always be greater than or equal
to CVL for normal comparator operation. QH and QL are
digital outputs that indicate where a voltage measurement
lies in relation to the CVH and CVL thresholds and are also
used to indicate when short circuit protection is engaged
as shown in Table 2.
The receiver thresholds can be used over a range of
+3V to VCC -3V. The VINP input of the receiver is designed
to withstand voltages from VEE+2V to VCC such that the
comparator input can be directly connected to the driver
output without being damaged.
Measurement is within the range
established by CVH and CVL
Measurement is above the range
established by CVH and CVL
Measurement is below the range
established by CVH and CVL
Short circuit protection is en-
gaged and Driver is disabled
5
Disable short circuit protection (SCP*=1) and
start running the driver at the desired operating
conditions.
Table 2. Comparator Output Truth Table
CVH
VINP
CVL
Condition
+
+
QH
1
0
1
0
www.semtech.com
QL
1
1
0
0
E7802
QH
QL
INT*
1
1
1
0
VEE