AN9201: Protection Circuits for Quad and Octal Low Side Power Drivers

No. AN9201.1
Application Note
April 1994
PROTECTION CIRCUITS FOR QUAD AND OCTAL
LOW SIDE POWER DRIVERS
by Wayne Austin
Overview
Normally, the defined requirements for a Quad or Octal Driver
are very much affected by the type of protection circuits used on
the chip. Fault protection for an open or shorted load is an interactive function, making it important in the decision process of
specifying the proper IC for an application. The various types of
on-chip features may include protection for over-current, overvoltage and over-temperature. The response action to a fault
condition may be either limiting or shutdown. Shutdown methods
may include hysteresis and may require a logic reset. On-chip
clamp diodes provide current steering to an external zener diode
clamp as over-voltage protection from inductive switching pulses.
Internal Zener diodes are also used to limit the output voltage on
the output driver of the IC. In addition, fault detection is available
with diagnostic feedback, including serial bus (SPI) control. All of
the protection features noted are represented in the Table 1 listing of Quad and Octal Low Side Drivers:
TABLE 1. QUAD & OCTAL LOW SIDE POWER DRIVERS
TYPE
CA3242
DESCRIPTION
Quad Gated Inverting
Power Dr.
CA3262
Quad Gated Inverting
Power Dr.
KEY FEATURES
Over-Current Latch-Off, Fast
Fault Shut-Down, Output
Protection Diodes
Over-Current Limiting, OverTemperature Limiting, Output
Protection Diodes
Same as CA3262 plus +125oC
Max. TA Range.
CA3262A Quad Gated Inverting
Power Dr.
CA3272 Quad Gated Inverting
Over-Current and Temp. Limand
Power Dr. with Fault
iting, Fault Flag Output,
CA3272A Mode Diag. Flag Output +125oC Max. TA Range.
CA3272A has improved Fault
Flag Output Drive Capability.
CA3282 Octal Driver with SPI
Over-Current and Over-VoltLogic Control
age Fault Mode Protection
with Fault Mode Feedback/
Control with -40oC to +125oC
Max. TA Range.
CA3292A Quad Gated Inverting
Similar to CA3272A with addPower Dr. with Fault
ed Internal Over-Voltage OutMode Diag. Flag Output put Clamp.
HIP0080 1A and 2A Quad Gated Over-Current (Latch-Off),
and
Inverting Power Drs.
Over-Temperature (GatesHIP0081 with Multi-mode Diag.
Off), Open Load and Output
Feedback
Ground Short Detection, OverVoltage Internal Output Clamp
Diodes, Fault Mode Feedback/Control and -40oC to
+125oC Max. TA Range.
Copyright
While the CA3282 Octal Driver is quite different from the
quad drivers, it is included here because it is used in similar
applications. The CA3282, HIP0080 and HIP0081 feature
Power BiMOS with MOSFET Output Drivers for higher current and voltage capability. Because of the additional
dissipation associated with these drivers, the CA3282 and
HIP0081 are provided in a 15 pin SIP power package. The
other Quad Drivers are available in the 16 pin DIP and/or 28
lead PLCC packages which have special construction for
improved heat dissipation. All of these Low Side Switches
generally share a common characteristic of 5V input CMOS
or TTL logic level control.
The Quad and Octal Power Drivers include a wide variation
of choice in selecting a device type. The available types are
listed in TABLE 1 which also highlights the key parameters
for most applications. By-type, the protection features of the
Quad and Octal Drivers are listed in the table and are
explained in the following detail of this IC Application Note to
assist the user in making an intelligent device selection for
the application of interest.
CA3242 Quad Power Driver
In normal use, the supply voltage is applied through a load to
an NPN open collector output of the CA3242 quad driver.
The functional block diagram is shown in Figure 1. The maximum current rating of 1A does not distinguish between
average and peak. Each output is independently protected
and latches “OFF” when the load current exceeds the latchoff threshold in the “ON” state. The CA3242E feature of
short circuit protection is a responsive high-speed shutdown
of the output drive to a shorted load. Under worse-case
shorted load conditions, the supply voltage is applied direct
to the output device. The latch-off threshold is typically 1.3V
(ISCRON), where RON is the saturated “ON” resistance of the
output. The CA3242 latches “OFF” at a typical short circuit
current of 1.2A with 25µs nominal delay. The ENABLE or the
IN pin of the latch-tripped channel must be toggled to reset
the latch.
To better understand the mechanism of protection when the
CA3242 is subjected to a shorting condition, Figure 2 illustrates that part of the Figure 1 noted as the “PROT”
functional block. When an over-load current is applied to an
output driver, the VSAT increases to a threshold level set in a
© Intersil Corporation 1992
11-170
Application Note 9201
TABLE 2. QUAD AND OCTAL DRIVER FEATURES
CA3292A
HIP0080
HIP0081
CA3282
(OCTAL
DR.)
60V
32V Typ.
(Clamp)
36V Typ.
(Clamp)
80V Typ.
(Clamp)
32V Typ.
(Clamp)
0.6A
0.6A
1A
2A
1A
0.5Ω at 1A
1Ω at 0.5A
CA3242
CA3262
CA3262A
CA3272
CA3272A
Max. Output Voltage,
No Load
50V
60V
60V
Max. Output Load
Current
0.6A
0.7A
0.7A
Max. VSAT Output Voltage 0.8V at 0.6A 0.6V at 0.6A 0.5V at 0.6A 0.4V at 0.5A 0.4V at 0.5A
Max. RON Output Resis1.0Ω at 0.5A
tance
Max. Load Switching
Voltage, VCE(SUS) or
VCLAMP Limited
35V
40V
40V
40V
28V
27V
73V
30V
Typical Output Current
Limiting and/or Shutdown
Protection
1.4A
(Latches
Off)
1.6A
1.3A
1.2A
1.2A
1.8A
(Latches
Off)
3.5A
(Latches
Off)
1.5A
(Latches
Off)
Output Thermal Limiting
and/or Shutdown Protection (Temp. TJ)
None
155oC
(Limits)
155oC
(Limits)
165oC
(15oC hys.)
165oC
(15oC hys.)
150oC
(15oC hys.)
150oC
(15oC hys.)
None
Over-Voltage Protection
Current Steering Clamp Diode
Fault Diagnostics
None
No
Temp. Range,
-40oC to __oC
Packages:
16 DIP Pwr WEB
(PC Bd, θJA)
28 PLCC Pwr WEB
(PC Bd, θJA)
15 SIP (Tab H.S., θJC)
105oC
85oC
40oC/W
40oC/W
40oC/W
30oC/W
30oC/W
IN D
IN C
V+
8
PROT
QD
10
OUT D
7
CLAMP
6
PROT
OUT B
2
CLAMP
1
PROT
IN A
Proper application will protect the CA3242E during turn-off
under shorted load conditions. Observations of wide ranging
conditions have been done to test the shutdown behavior
and has revealed several pitfalls that should be addressed to
assure safe shutdown. One should be aware that a forced
short circuit test condition may be considerably more severe
than a normal application shorted load. In either case, two
problems arise that affect the severity of the overload during
shutdown. These are:
1. A shorted load is inductive and causes the generation of
voltage spikes, exposing the output device to at least 2
times the value of the V+ supply voltage.
3
PROT
QB
16
3oC/W
2. Lack of bypassing can provoke severe oscillations during
the delay period before shutdown is complete. This is typically less than 25µs.
14
ENABLE
IN B
30oC/W
OUT C
QC
15
30oC/W
3oC/W
11
9
Fault Mode Flag and Feedback
125oC
comparator circuit. The comparator outputs a switching signal to the protection latch and the input drive is “latched-off”.
The input may be reset with an INPUT or ENABLE toggle, or
by and ON-OFF toggle of the power supply to the control circuits.
VCC
Zener Diode Feedback Clamp
Fault Flag
OUT A
QA
PINS 4, 5, 12 AND 13
GROUND
FIGURE 1. CA3242 FUNCTIONAL BLOCK DIAGRAM
The result of this oscillation with an inductive load is to alternately stress the output device in both a forward and reverse
direction at rates as high as 1mHz, lasting until shutdown
occurs. This problem is compounded in some applications
when 2 or more devices are used in parallel to increase drive
output. In this case, a short may now draw twice the current of
one driver which, in turn, results in almost twice the unclamped
voltage spike developed across each output transistor.
To suppress oscillations during shutdown requires some
attention to the use of adequate bypassing of both the +5V
VCC supply and the battery or output supply voltage.
Bypassing the output supply will minimize both the transient
oscillations and the voltage spike effects of lead inductance.
11-171
Application Note 9201
Then, the shorted output is stressed in the forward bias
mode with the shorted current determined by voltage
source, duration of short, line resistance and the resistance
of the saturated output. In a practical application, the load
and any potential short may occur in a remote location. As
such, bypassing the output supply may not be practical.
Bypassing the +5V supply with a 0.1µF capacitor closely
wired to pins 11 and 12 of the CA3242E constitutes adequate bypassing of the +5V supply.
Because voltage spikes are normal to the application, a 30V
zener “clamp” diode is needed to limit the device output voltage spikes to less than the maximum rating of 35V. The
zener clamp diode protection should be closely wired to pins
of the output divide in order to avoid any delay in the voltage
clamping action. Alternatively, the on-chip diodes may be
used in a free wheeling mode by connecting the CLAMP
pins to the supply voltage if it does not exceed 30V during
transients. Zener diode clamp protection is preferred over
the power supply clamp option, primarily because the power
supply may be subject to large transient changes.
CLAMP
INPUT_
+VCC
OUT_
ENABLE
VREF
SCR
LATCH
+
-
FIGURE 2. CA3242 FUNCTIONAL DIAGRAM FOR EACH OUTPUT
CHANNEL SHOWN WITH PROTECTION CIRCUIT
CA3262 and CA3262A Quad Power
Drivers
The CA3262 is a quad-gated inverting low-side driver capable of switching 700mA load currents (at +25oC) in each
output without interaction between the outputs. Shown in
Figure 3, each output is independently protected with overcurrent limiting and over temperature limiting features. If an
output load is shorted, the remaining three outputs function
normally unless the junction temperature of their output
device exceeds the over temperature limiting threshold of
+155oC (typical). Current limiting prevents the output current
from exceeding a value determined by the design (1.2A typical), independent of the load condition. The power
dissipation of the shorted output driver is equal to the product of the limiting value of current and the applied output
collector voltage. If this value causes the junction temperature to exceed +155oC (typical), the base drive to the output
transistor, and thereby it’s collector current, is reduced until
the resulting power dissipation is equal to that value which
maintains the junction temperature at the thermal limit value.
The current which flows in the output transistor in a short circuit mode is therefore a function of the ambient temperature,
the thermal resistance of the package in the application, the
total power dissipated in the package. If the short is
removed, normal operation resumes automatically.
In order to clamp high voltage pulses which may be generated by switching inductive energy in the load circuit, zener
diodes with a value not greater than 30V should be connected to the CLAMP pins. On-chip diodes are connected
from each output to one of the two CLAMP pins and are
intended for use as steering diodes to provide a path for the
clamped pulse current to a CLAMP pin; allowing the use of
one zener diode to clamp all outputs. Alternatively, the onchip diodes may be used in a free-wheeling mode by connecting the CLAMP pins to the supply voltage if it does not
exceed 30V during transients. Zener diode clamp protection
is preferred over the power supply clamp option, primarily
because the power supply voltage may be subject to large
transient changes. Note that the rate of change of the output
current during switching is very fast. Therefore, even small
values of inductance (such as the inductance of several
meters of wire) in the load circuit can generate voltage
spikes of considerable amplitude on the output terminals and
may require clamping to prevent damage.
The CA3262A is a lower VSAT version of the CA3262 and is rated
for +125oC ambient temperature applications. The CA3262 is
limited to about +100oC (data sheet rating at +85oC) ambient
temperatures. Otherwise, the protection features described here
apply to both versions. Figure 3 shows a functional block diagram
for the CA3262 and CA3262A. Each type has independent current limiting and thermal limiting protection for each output driver.
The maximum current rating of each output is typically greater
than 1.2A. However, this is not a users choice rating, the current
limiting may range from 0.7A to as high as 2A.
Typical applications of the CA3242 and CA3262 quad drivers with the recommended method for use of the current
steering diodes is shown in the circuit of Figure 4. Where
inductive loads are not used, the protective diodes need not
be externally connected. However, the user should be alert
to the potential for stored energy in long wire connections to
the load circuits.
VCC
11
V+
(18)
9
IN D
8
TLIM
(16)
ILIM
10
IN C
EN
IN B
(17)
14
(26)
15
TLIM
ILIM
3
TLIM
(27)
ILIM
16
IN A
OUT D
(14)
7
CLAMP
(13)
6
OUT C
(12)
TLIM
(4)
2
OUT B
CLAMP
(3)
1
OUT A
(2)
(28)
ILIM
PINS 4, 5, 12 AND 13 GROUND (PACKAGE E)
PINS 5-11 AND 19-25 GROUND (PACKAGE Q)
PIN #’S IN PARENTHESIS APPLY TO PACKAGE Q
FIGURE 3. CA3262 AND CA3262A FUNCTIONAL BLOCK
DIAGRAM
11-172
Application Note 9201
11
+5V
P.S. (18)
9
V+
8
TLIM
RELAY
(14)
7
(16)
ILIM
(13)
TLIM
(12)
VBATT
6
10
TTL OR
CMOS
LOGIC
LEVEL
INPUTS
(17)
14
VBATT
ILIM
3
(26)
15
SOLENOID
TLIM
(4)
2
(27)
MOTOR
HIGH CURRENT
HIGH SIDE DR
(3)
ILIM
1
16
TLIM
(2)
LAMP
VBATT
(28)
ILIM
FIGURE 4. TYPICAL APPLICATION CIRCUIT FOR THE CA3262 AND CA3262A QUAD POWER DRIVERS WITH PROTECTION DIODES EXTERNALLY CONNECTED TO A ZENER CLAMP DIODE FOR INDUCTIVE LOAD PROTECTION.
The CA3262 and CA3262A will typically survive when
shorted if the output supply voltage is less than 18V. This
potential for failure is flagged in the data sheet as a note
under the Electrical Characteristics table. It takes a few milliseconds to shutdown when the output is short circuited.
During shutdown the dissipation may be excessive and is
primarily determined by ISC which is the limiting current. The
short-circuit current will be limited but the voltage that the
shorted output sees may approach VSUPPLY. Not considering
transient effects, the worst case dissipation would be PD =
(VSUPPLY)x(ISC). Normally, a shorted solenoid or relay will
have a few ohms of impedance which should prevent catastrophic IC failure in 12V automotive applications. A typical
value for ISC is 1.3A. RON is the saturated collector resistance of the output transistor with a typical value of 1Ω.
VSUPPLY is normally 9V to 16V in automotive applications.
The thermal shutdown could be made faster but the circuit
would not be able to effectively drive lamps which have a
very low resistance in a cold start-up. Lamp drive capability
is a common application use for the CA3262 and CA3262A.
down characteristics differ from the CA3262 by having
hysteresis, the same precaution applies for potential damage from high transient dissipation during thermal shutdown.
The CA3272Q, CA3272AQ and CA3292AQ Quad Driver are
provided in the 28 pin web-leadframe PLCC package. This
package has slightly lower thermal resistance than the 16
lead DIP package with a web leadframe.
CA3272 and CA3292 Quad Power Drivers
with Fault Mode Flag
The FAULT DETECTOR circuit of the CA3272, CA3272A
and CA3292A is shown in Figure 6 as an equivalent logic
block diagram. Channel A is one of 4 power switching functions displayed in the diagram. Transistor QA is the protected
power transistor switch that drives the “OUT A” terminal. The
FAULT DETECTOR block illustrates the logic functions associated with FAULT DETECTION. The ENABLE input is
common to each of the 4 power switches and also disables
the FAULT output when it is low. From the “IN A” input to the
“OUT A” output, the switch condition is inverting (NAND).
When IN is high, OUT is low. The FAULT DETECTOR
senses the IN and OUT states and switches QF “ON” if a
fault is detected. Transistor QF activates a sink current
source to pull-down the FAULT pin to a 0 (low) state when
the fault is detected. Both shorted and open load conditions
are detected.
The CA3272 and CA3292 are quad-gated inverting low-side
power drivers with a fault diagnostic flag output. They are
rated for +125oC ambient temperature applications and
have current limiting and thermal shutdown. As shown in
Figure 5, they differ from the CA3262A by not having output
clamp diodes but do have the diagnostic short-circuit flag
outputs. Each output driver is capable of switching 400mA
load currents at +125oC ambient without interaction between
the outputs. Current limiting functions in the same manner
as the CA3262 with a typical limit value of 1.2A. The current
limiting range is set for 0.6A to 1.6A. While the thermal shut-
The CA3292A is equivalent to the CA3272A except that it
has internal clamp diodes on the outputs to handle inductive
switching pulses from the output load. The CA3272A and
CA3292A have significantly higher IOL FAULT output drive
than the CA3272. Expanded functional block diagram detail
of the fault logic is similar to that of the CA3272 as shown in
Figure 6. The structure of each CA3292A output, shown in
Figure 6B, includes a zener diode from collector-to-base of
the output transistor. This is a different form of protection
than the CA3242 or CA3262 which have current steering
clamp diodes on each output, paired to one of two “CLAMP”
11-173
Application Note 9201
output pins. The CA3292A output transistor will turn-on at
the clamp voltage threshold which is typically 32V and the
output transistor will dump the pulse energy through the output driver to ground.
VCC
18
OUT D
14
ENABLE
26
F
TLIM
IN D
0.02Ω
QD
16
ILIM
OUT C
12
F
TLIM
IN C
QC
0.02Ω
17
ILIM
F
OUT B
4
TLIM
IN B
0.02Ω
QB
27
ILIM
F
OUT A
2
TLIM
IN A
ILIM
0.02Ω
QA
28
FAULT
1
GROUND
PINS 5-11, 19-25
FIGURE 5. CA3272 AND CA3272A FUNCTIONAL BLOCK
DIAGRAM
Each of the outputs are independently protected with overcurrent limiting and over-temperature shutdown with thermal
hysteresis. If an output is shorted, the remaining outputs
function normally unless the temperature rise of the other
output devices can be made to exceed their shutdown temperature of +165oC (typical). When the junction temperature
of a driver exceeds the +165oC thermal shutdown value, that
output is turned off. When and output is shutdown, the
resulting decrease in power dissipation allows the junction
temperature to decrease. When the junction temperature
decreases by approximately 15oC, the output is turned on.
The output will continue to turn on and off for as long as the
shorted condition exists or until shutdown by the input logic.
The resulting frequency and duty cycle of the output current
flow is determined by the ambient temperature, the thermal
resistance of the package in the application, the total power
dissipation in the package. Since each output is independently protected, the frequency and duty cycle of the current
flow into multiple shorted outputs will not be related in time.
Long lead lengths in the load circuit may lead to oscillatory
behavior if more than two output loads are shorted.
A diagnostic flag indicates when an output is shorted. This
information can be used as input to a microprocessor or dedicated logic circuit to provide a fast switch-off when a short
occurs and also to determine by sequence action, which output is shorted. A fault condition in any output load will cause
the FAULT output to switch to a logic “low”. Added detail of
the fault logic is shown in Figure 6A. Since a fault condition
will be indicated during switching, use of an appropriate size
capacitor to filter the FAULT output is recommended (see
data sheet). This will prevent the FAULT output voltage from
reaching a logic level “0” within the maximum switching time.
The FAULT detection circuitry compares the state of the input
and the state of the output. The output is considered to be in
a high state if the voltage exceeds the typical FAULT threshold reference voltage, VTHD of 4V. If the output voltage is less
1
TO CHANNELS
B, C AND D
FAULT
OVER-VOLTAGE
ZENER CLAMP
DIODE
QF
ENABLE
TO B,C,D
AND FAULT
4V
EN
FAULT
DETECTOR
ENABLE
2
TLIM
OUT A
2
TLIM
IN A
OUT A
QA
QA
ILIM
ILIM
0.02Ω
FIGURE 6A. FAULT DETECTOR SHOWN WITH THE CA3272 AND CA3272A
OUTPUT STAGE
0.02Ω
FIGURE 6B. CA3292A OUTPUT STAGE WITH
CLAMP DIODE
FIGURE 6. FAULT DETECTION FUNCTIONAL BLOCK DIAGRAM OF THE CA3272, CA3272A AND CA3292A
11-174
Application Note 9201
than VTHD, the output is considered to be in a low state. For
example, if the input is high and the output is less than V THD,
a normal “ON” condition exists and the FAULT output is high.
If the input is high and the output is greater than V THD, a
shorted load condition is indicated and the FAULT output is
low. When the input is low and the output is greater than
VTHD, a normal “OFF” condition is indicated and the FAULT
output is high. If the input is low and the output is less than
VTHD, an open load condition exists and the FAULT output is
low. The FAULT output is disabled when the ENABLE input
logic level is low.
To detect an open load, each output has an internal low-level
current sink which acts as a pull-down under open load fault
conditions and is always active. The magnitude of this
current plus any leakage associated with the output
transistor will always be less than 100µA. (The data sheet
specification for ICEX includes this internal low-level sink
current). The output load resistance must be chosen such
that the voltage at the output will not be less than VTHD
when the ICEX sink current flows through it under worse
case conditions with minimum supply voltage. For example,
assume a 6.5V minimum driver output supply voltage, a
maximum FAULT threshold reference voltage of VTHD = 5.5V
and an output current sink of ICEX = 100µA. Calculate the
maximum load resistance that will not result in a FAULT
output low state when the output is OFF.
RLOAD(max) = [VSUPPLY (min) - VTHD (max)] / ICEX (max)
RLOAD(max) = ( 6.5V - 5.5V ) / 100µA = 10kΩ
Since the CA3272 and CA3272A do not have on-chip diodes
to clamp voltage spikes which may be generated during
inductive switching of the load circuit, external zener diodes
(30V or less) should be connected between the output terminal and ground. Only those outputs used to switch inductive
loads require this protection. Note that since the rate of
change of output current is very high, even small values of
inductance can generate voltage spikes of considerable
amplitude on the output terminals which may require clamping. External free-wheeling diodes returned to the supply
voltage are generally not acceptable as inductive clamps if
the supply voltage exceeds 30V during transients.
CA3282 Octal Power BiMOS Driver with
SPI Bus
The CA3282 is a logic controlled Power Driver with a Serial
Peripheral Interface (SPI). The chip is fabricated in a Power
BiMOS process with high voltage and current drive capability. A
functional block diagram is shown in Figure 5. There is an extensive amount of logic circuitry to provide individual diagnostic
feedback; including which output may be shorted. Each of the
open collector output drivers has individual protection for overcurrent and overvoltage; and, each output has separate output
latch control. The current limiting of the CA3282 is set for a range
of 1A to 2A (1A min.). In the normal ON state, each output driver
is in a saturated low state. Comparators in the diagnostic circuit
monitor the drain of the output drivers to determine if an out-ofsaturation condition exists. If a comparator senses a voltage
higher than the threshold trip level of 3V typical, the latch control
circuit is reset (unlatched) and the respective output driver is
shutdown. The on-chip current limiting protection is independent
of the diagnostic feedback loop. If an over-current condition
exists, the condition may be sustained unless the diagnostic circuit senses a fault condition. Open-load faults may be detected
with a diagnostic check of the output in the off state. A 150µA
typical internal current sink pull-down forces the output low when
it would otherwise be high.
Maximum current ratings allow all eight outputs to be turned
on to a level of 0.5A. This is allowed because the CA3282 chip
is packaged in 15 pin SIP power package with 3oC/W typical
junction-to-case thermal resistance, allowing high dissipation
capability in ambient temperatures up to 125oC. The CA3282
output driver structure consists of a MOSFET with a zener
diode feedback from the drain to gate, forming an overvoltage
clamp structure for protection from voltage spikes generated
when switching inductive loads. The pulse energy is shunted
to ground through the MOSFET output driver.
The CA3282 protection features support many application
requirements. A typical application circuit is shown in Figure
8. Where inductive loads are used, no external diode is
needed to shunt the load coil turn-off pulse. However, it is
important to adhere to the maximum peak current ratings for
currents that can flow in the output devices. The output drivers are turned-on by an internal zener feedback for over-
OUTPUT#0
(1 OF 8)
DATA_IN
(MISO)
CLOCK
(SCK)
DATA_OUT
(MISO)
SHIFT
REGISTER
OUTPUT
LATCH
SPI
INTERFACE
CIRCUIT
CE
CURRENT
LIMIT
CONTROL
LOGIC
RESET
DIAGNOSTIC
CIRCUITRY
TO DRIVERS
1 THRU 7
FIGURE 7. CA3282 BLOCK DIAGRAM FOR ONE OF EIGHT DRIVER STAGES
11-175
Application Note 9201
+VCC
RELAY
MOSI
(DATA_IN)
SOLENOID
SCK
(CLOCK)
LAMP
CA3282
OCTAL DRIVER
TO OTHER RELAYS
AND SOLENOIDS FOR
SPEED CONTROL
VENT AND VACUUM,
PURGE, EGR, A/C
AND OTHER SWITCH ACTUATOR FUNCTIONS
MISO
(DATA_OUT)
SPI BUS
CE
RESET
FIGURE 8. CA3282 TYPICAL APPLICATION CIRCUIT WITH SPI BUS CONTROL
VCC1
1 OF 4 SWITCH/CHANNELS
100KΩ
IN1
DR1-CNTL
POR
COMP
G.S.
FILTER
COMP
COMP
POR
(PWR-ON-RST)
DATAIN
500 KHz OSC
(FILTER - F CLK)
(NOTE 1)
ENABLE
OUT1
80V
TEMP.
SENSE
SC
EN
CONTROL AND 16 BIT
DIAGNOSTIC SHIFT FCLK
DO
REGISTER
CLK
DATAOUT
10
kΩ
VREFG.S.
DR
EN
TS
S.C.
FILTER
CS
VREF
O.L.
10KΩ
VCC1
O.L.
FILTER
VREF
ISC
LIMIT
GND
VCC1
14V
BANDGAP
REF. AND BIAS
VOLTAGE
SOURCES
LOW IDLE CURRENT
POWER DOWN SWITCH
(HIP0080 ONLY)
100KΩ
NOTE:
1. HIP0080 - no enable hysteresis.
FIGURE 9. EQUIVALENT FUNCTION BLOCK DIAGRAM OF THE HIP0080 AND HIP0081
11-176
0.01Ω
VCC
Application Note 9201
voltage clamp protection of each output. The circuit of Figure
8 illustrates an automotive application where a CDP68HC05
microprocessor or equivalent controls the SPI bus and determines what action if any will happen when a fault is detected.
In this way the CA3282 is designed to support a variety of
applications such as industrial controls. Due to the high cold
starting current of lamp loads, it is not advisable to switch-on
more than one lamp load at a time. Included in the many features of the CA3282 is a very low logic supply current to
support the needs for low stand-by current drain.
HIP0080 and HIP0081 Quad Power
MOSFET Drivers with Serial Diagnostic
Interface
The HIP0080 and HIP0081 are low side power switches
fabricated in a Power BiMOS process technology. They can
typically sustain higher voltage and current capability than
Power Bipolar ICs. Except for package and pinout
differences, both circuits are functionally similar as shown in
the functional block diagram of Figure 9. The HIP0080 and
HIP0081 are designed to sustain 1A and 2A respectively of
DC output current drive. The output drivers are voltage rated
up to the clamp level set by drain-to-gate zener diodes and
typically clamp at 80V for the HIP0081 and 36V for the
HIP0080. A 15 pin SIP power package is used to achieve
maximum capability for the HIP0081 while the HIP0080 is
available in the 28 pin PLCC web lead frame package.
The diagnostic monitoring and feedback process of the
HIP0080 and HIP0081 is different from the CA3282. Each
output device is independently toggled on or off through a
driver interface circuit that is, in part, controlled by overcurrent and over-temperature diagnostic feedback. The
conditions on each output device are monitored to sense
over-current, over-temperature, open-load and output-ground
shorting. Four separate bits for each of the four outputs are
loaded into a 16 bit serial diagnostic register. The diagnostic
information is accessed with a low on the chip select pin and
the clock input. Both DATA IN and DATA OUT pins are
available to allow cascade operation. The first bit in the data
readout is a fault error flag which is high if any one of the
following 16 bits indicate a fault condition. When chips are
cascaded, the error flags are cascaded and a fault condition is
immediately evident if there is a fault on any chip. Although, all
bits must be read to determine where, if any, the fault
condition exists. While the diagnostic interface for data
gathering purposes is quite different than the CA3282, the
drive control and diagnostic feedback is SPI Bus compatible.
Another part of the diagnostic feedback circuits provides for
digital delay filtering to prevent short transient over-current
and output voltage readings from loading the diagnostic register with false data. Each output is sensed with a window
comparator to determine whether the output is high, low or
centered. A resistor divider consisting of two 10KΩ resistors
sets a reference voltage level for the window comparator.
When a centered reading is detected with the driver output off,
the centered reading is sensed as a no load condition on the output. If the window comparator senses a low reading when the
driver output is off, the result is interpreted as a short to ground.
The results are passed through a digital delay filter and are transmitted to the diagnostic shift register. The over-current sense
level is read from a metal source-to-ground resistance in each
output by a comparator that senses the voltage as a current.
When an over-current level is detected, the result is sent through
a digital delay filter to the diagnostic shift register and also toggles a latch circuit in the drive control which cuts-off drive to the
output stage. Where a shorted condition exists, the short must be
removed and the input toggled off and on to reset normal operation. If an over-temperature condition is sensed, the feedback
result is fed directly back to the input control stage to gate-off
drive to the output stage while also loading the diagnostic shift
register. Normal chip operation may resume when the chip is sufficiently cooled. There is a typical 15οC hysteresis shift intended
by design to provide a cooling cutoff period.
Summary
While this information on the protective structures of the Quad
& Octal Power Drivers should be helpful, it must also be
recognized that the design of the application circuit should be
consistent with performance requirements. Generally, the data
sheets define parameters in terms of each separate switch.
Although the data sheets do not specify parallel switch ratings
and limits, the switches may be used in parallel to increase
current drive capability. Also, there are a number of design
considerations that will impact the continuing performance and
reliability of the IC. The protective features of the Quad and
Octal Drivers discussed here provide substantial system
application protection by reducing the potential for catastrophic
failure. To provide the user with a better in-sight into the device
on-chip functions, the function block diagrams with their
respective protection features have been included here.
Additional detail can be found in the data sheet for each type.
References
1. CA3262, CA3272 distributed Automotive Brochures provided a document titled “Quad Power Drivers”, No. BR002. (Stress Data)
2. CA3262 - PCIM June 1988 article titled “Current and
Temperature Limiting Protect Power Switch Driver
Outputs” which has shutdown timing information to show
the independent action of shutdown plus other
application detail.
For reference, the data sheet file numbers are listed by type
as follows:
TYPE
NO.
TYPE
NO.
CA3242
1561.2
CA3282
2767.4
CA3262, CA3262A
1836.3
CA3292A
2223.3
CA3272, CA3272A
2223.3
HIP0080, HIP0081
3018.2
Acknowledgments
The material presented here has been written by Wayne
Austin, Intersil Intelligent Power Product Applications of the
Intersil Automotive Design Center, Somerville, NJ with contributions from Tom DeShazo, Lou Pennisi, Bob Kumbatovic
and Paul Dackow.
11-177
Application Note 9201
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Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design and/or specifications at any time without
notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate
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