TI TPIC2802

TPIC2802
OCTAL INTELLIGENT-POWER SWITCH
WITH SERIAL INPUT
SLIS013 – APRIL 1992
•
•
•
•
•
•
•
•
•
•
8-Bit Serial-In Parallel-Out Driver
1-A Output Current Capability Per Channel
or 8-A Total Current
Overcurrent Limiting and Out-of-Saturation
Voltage Protection on Driver Outputs
Contains Eight Open-Collector Saturating
Sink Outputs With Low On-State Voltage
High-Impedance Inputs With Hysteresis Are
Compatible With TTL or CMOS Levels
Exceptionally Low On-State Supply Current
50 mA
Very Low Standby Power
20 mW Typical
Status of Output Drivers May Be Monitored
at Serial Output
3-State Serial Output Permits Serial
Cascading or Wire-AND Device
Connections
45-V Transient Clamping With Inductive
Switching on Outputs, 20-mJ Rating Per
Driver Output
KV PACKAGE
(TOP VIEW)
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
Y4
Y5
Y6
Y7
RST
VCC
SO
GND
SI
SCLK
SIOE
Y0
Y1
Y2
Y3
The tab is electrically connected to GND.
description
The TPIC2802 octal intelligent-power switch is a monolithic BIDFET† integrated circuit designed to sink currents
up to 1 A at 45 V simultaneously at each of eight driver outputs under serial input data control. Furthermore,
use of a Darlington output structure enables an 80% reduction in the on-state supply current compared with
earlier designs. Status of the individual driver outputs is available in serial data format. The driver outputs have
overcurrent limiting and out-of-saturation voltage protection features. Applications include driving solenoids,
relays, dc motors, lamps, and other medium-current or high-voltage loads.
The device contains an 8-bit serial-in, parallel-out shift register that feeds an 8-bit parallel latch, which
independently controls each of the eight Y-output drivers.
Data is entered into the device serially via the serial input (SI) and goes directly into the lowest bit (0) of the shift
register. Using proper timing signals, the input data is passed to the corresponding output latch and output driver.
A logic-high SI bit n turns the corresponding output driver (Yn)off. A logic-low bit at SI turns the corresponding
output driver on. Serial data is transferred into SI on the high-to-low transition of the serial clock (SCLK) input
in 8-bit bytes with data for the Y7 output (most significant bit) first and data for Y0 output (least significant bit)
last. Both SI and SCLK are active when the serial input-output enable (SIOE) input is low and are disabled when
SIOE is high.
Each driver output is monitored by a voltage comparator that compares the Y-output voltage level with an
internal out-of-saturation threshold voltage reference level. The logic state of the comparator output is
dependent upon whether the Y output is greater or smaller than the reference voltage level. While SIOE is held
high, an activated driver output is unlatched and turned off when the output voltage exceeds the
out-of-saturation threshold voltage level except when the internal unlatch enable is low and disabled. The
high-to-low transition of SIOE transfers the logic state of the comparator output to the shift register.
† BIDFET – Bipolar, double-diffused, N-channel and P-channel MOS transistors on same chip. This is a patented process.
Copyright  1994, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
2–1
TPIC2802
OCTAL INTELLIGENT-POWER SWITCH
WITH SERIAL INPUT
SLIS013 – APRIL 1992
functional block diagram
RST
Retriggerable
One Shot
H
11
One Shot
SIOE
SI
SCLK
100 µs
1D
C1
R
5
200 ns
SR Bit 0
S
1D
7
4
S
1D
49 V
R
Comparator STD
SR Bit 1
S
1D
+
–
10 V
CC
1.8-V
Reference
Y1 Output Latch
3
S
1D
Y1
49 V
C1
C1
R
SY1
Channels 2– 6
To D of SR3
From Q of SR6
SR Bit 7
S
1D
+
–
1.8-V
Reference
Y7 Output Latch
12
S
1D
49 V
C1
C1
R
SY7
SO Latch
1.8-V
Reference
9
C1
R
POST OFFICE BOX 655303
+
–
3-State Buffer
1D
2–2
Y0
C1
C1
6
Y0 Output Latch
• DALLAS, TEXAS 75265
SO
Y7
TPIC2802
OCTAL INTELLIGENT-POWER SWITCH
WITH SERIAL INPUT
SLIS013 – APRIL 1992
Terminal Functions
PIN
I/O
DESCRIPTION
NAME
NO.
GND
8
RST
11
I
Reset. An asynchronous reset is provided for the shift register and the parallel latches. This terminal is active when
low and has no internal pullup. When active, it causes the power outputs to turn off. A power-on clear can be
implemented using an RC network to VCC.
SCLK
6
I
Serial clock. This terminal clocks the shift register. The serial output (SO) changes state on the rising edge of SCLK
and serial input (SI) data is accepted on the falling edge.
SI
7
I
Serial Input. A high on this terminal programs a particular output to be off, and a low turns it on.
SIOE
5
I
Serial input-output enable. Data is transferred from the shift registers to the power outputs on the rising edge of this
signal. The falling edge of this signal parallel loads the output voltage sense bits from the power output stages into
the shift register. The output driver SO is enabled when this terminal is low, provided RST is high.
SO
9
O
Serial output. This terminal is the serial 3-state output from the shift register and is in a high-impedance state when
SIOE is high or RST is low. A high for a data bit on this terminal indicates that the corresponding power output (Yn)
is high. This means that the output was programmed to be off the last time a byte was input to the device or that
the output faulted and was latched off by the output voltage-sense indicator. A low on this output indicates that the
corresponding power output (Yn) is low (on output stage or open-circuit condition).
VCC
Y0
Y1
Y2
Y3
Y4
Y5
Y6
Y7
Ground. Common return for entire chip. The output current from this terminal is potentially as high as 8 A if all outputs
are on. GND is used for both logic and power circuits.
10
4
3
2
1
15
14
13
12
5-V supply voltage
O
Power outputs. These outputs are provided with current limiting and voltage sense for fault indication and protection.
The nominal load current for these outputs is 500 mA, and the current limiting is set to a minimum of 1 A. The
active-low outputs also have voltage clamps set at about 45 V for recirculation of inductive load current. Internal
90-kΩ pulldown resistors are provided at each output. These resistors hold the output low during an open-circuit
condition.
schematic of inputs and outputs
EQUIVALENT OF ALL LOGIC INPUTS
(SI, SCLK, SIOE, RST)
EQUIVALENT OF SERIAL
OUTPUT (SO)
EQUIVALENT OF Y OUTPUTS (Yn)
VCC
VCC
VCC
Output
49 V
Input
Output
90 kΩ
GND
All resistor and voltage values shown are nominal.
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
2–3
TPIC2802
OCTAL INTELLIGENT-POWER SWITCH
WITH SERIAL INPUT
SLIS013 – APRIL 1992
absolute maximum ratings over operating temperature range (unless otherwise noted)
Supply voltage range, VCC (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 0.3 V to 7 V
Input voltage, VI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
Output voltage range, SO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 0.3 V to 7 V
Input current, II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –15 mA
Peak output sink current at Y, IO repetitive, tw = 10 ms, duty cycle = 50%,
(see Notes 2 and 3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . internally limited
Continuous output current at Y, IO (see Note 3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 A
Peak current through GND terminal: Nonrepetitive tw = 0.2 ms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 8 A
Repetitive tw = 10 ms, duty cycle = 50% . . . . . . . . . . . . . . . . . . . . – 6 A
Continuous current through GND terminal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 4.5 A
Single-pulse avalanche energy rating, EAS (see Note 4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 mJ
Avalanche current, IAS(max) (see Note 5) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 A
Continuous dissipation at (or below) TA = 25°C (see Note 6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.575 W
Continuous dissipation at (or below) TC = 75°C (see Note 6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 W
Operating case or virtual-junction temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 55°C to 150°C
Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 65°C to 150°C
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260°C
NOTES: 1. All voltage values are with respect to network GND.
2. Each Y output is individually current limited with a typical overcurrent limit of about 1.8 A.
3. Multiple Y outputs of this device can conduct rated current simultaneously; however, power dissipation (average) over a short time
interval must fall within the continuous dissipation range and the GND terminal current range.
4. VCC = 20 V, starting TJ = 25°C, L = 310 mH, IAS = 0.28 A.
5. VCC = 10 V, starting TJ = 25°C, L = 8 mH, IAS = 1 A (see Figure 6).
6. For operation above 25°C free-air temperature, derate linearly at the rate of 28.6 mW/°C. For operation above 75°C case
temperature, derate linearly at the rate of 333 mW/°C. To avoid exceeding the maximum virtual-junction temperature, these ratings
must not be exceeded.
recommended operating conditions
Supply voltage, VCC
MIN
NOM
MAX
UNIT
4.75
5
5.25
V
High-level input voltage, VIH
0.75 VCC
5.25
V
Low-level input voltage, VIL
– 0.3
0.2 VCC
V
Output voltage, VO(off)
45
Continuous output current, IO(on)
Operating case temperature, TC
– 40
25
V
1
A
105
°C
electrical characteristics over recommended operating virtual junction temperature range (unless
otherwise noted)
PARAMETER
ICC
2–4
Supply current
TEST CONDITIONS
All outputs on,
All outputs off,
POST OFFICE BOX 655303
IO = 0.5 A at all outputs
TJ = 25°C
• DALLAS, TEXAS 75265
MIN
TYP
MAX
50
4
10
UNIT
mA
TPIC2802
OCTAL INTELLIGENT-POWER SWITCH
WITH SERIAL INPUT
SLIS013 – APRIL 1992
electrical characteristics over recommended operating virtual junction temperature range (unless
otherwise noted) (continued)
driver array outputs (Y0 to Y7)
PARAMETER
VOK
VO(on)
( )
Output clamp voltage
On-state output voltage
VTOS
Out-of-saturation threshold voltage
IO(off)
IO(cl)
Off-state output current
Output current limit
TEST CONDITIONS
IO = 0.5 A,
MIN
TYP†
45
49
Output programmed off and current
shunted to ground
IOL = 0.175 A
IOL = 0.5 A
With one output
programmed on and
conducting
d ti
UNIT
V
1
V
1
1.3
V
1.2
1.5
V
1.4
1.6
V
1.6
1.8
2.1
V
600
µA
1
1.8
A
40
90
kΩ
IOL = 0.75 A
IOL = 1 A,
During unlatch disable
With output programmed on and an overcurrent fault
condition
MAX
VO = 24 V with output programmed off
VO = 3 V with output programmed on
Internal output pulldown resistor
shift register (Inputs SI, SCLK, SCLK, and RST)
PARAMETER
VIT+
VIT –
Positive-going threshold voltage
Vhys
II
Hysteresis voltage (VIT+ – VIT–)
Ci
Input capacitance
TEST CONDITIONS
MIN
MAX
UNIT
0.75 VCC
Negative-going threshold voltage
0.1 VCC
V
0.85
Input current
V
2.5
V
± 10
µA
20
pF
TYP†
MAX
UNIT
0.2
0.4
VI = 0 to VCC
VI = 0 to VCC
shift register (output SO)
PARAMETER
VOL
VOH
Low-level output voltage
High-level output voltage
IO
Output current
Co
Output capacitance
† All typical values are at VCC = 5 V, TJ = 25°C.
TEST CONDITIONS
IO = 1.6 mA
IO = – 0.8 mA
MIN
VCC –1.3
VO = 0 to VCC,
VO = 0 to VCC,
V
V
SIOE input high
±20
µA
SIOE input high
20
pF
timing requirements over recommended ranges of supply voltage and operating case temperature
(see Figure 1)
MIN
MAX
UNIT
0
1
MHz
fclock
tw(SCLKH)
Clock frequency, SCLK
tw(SCLKL)
tw(RST)
Pulse duration, SCLK low
tsu1
tsu2
Setup time, SIOE↓ before SCLK↑
tsu3
th1
tr
tf
Rise time, SCLK, SI, SIOE
90
ns
Fall time, SCLK, SI, SIOE
90
ns
Pulse duration, SCLK high
See Note 7
Pulse duration, RST low
410
ns
410
ns
1200
ns
1
µs
Setup time, SCLK↓ before SIOE↑
1
µs
Setup time, SI high before SCLK↓
150
ns
Hold time, SI low after SCLK↓
150
ns
NOTE 7: For cascaded operation, the clock pulse durations (tw(SCLKL) and tw(SCLKH)) must be a minimum of 700 ns (giving a maximum clock
frequency of 632 kHz).
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
2–5
TPIC2802
OCTAL INTELLIGENT-POWER SWITCH
WITH SERIAL INPUT
SLIS013 – APRIL 1992
thermal characteristics
PARAMETER
RθJC
Thermal resistance, junction-to-case temperature
RθJA
Thermal resistance, junction-to-ambient temperature
MIN
MAX
UNIT
3
°C/W
35
°C/W
switching characteristics over recommended ranges of supply voltage and operating case
temperature
PARAMETER
FROM
(INPUT)
TO
(OUTPUT)
TEST CONDITIONS
MIN
MAX
UNIT
ten
tdis
Enable time
SIOE↓
SO
CL = 20 pF,
RL = 1 kΩ,
See Figure 2
1000
ns
Disable time
SIOE↑
SO
CL = 20 pF,
RL = 1 kΩ,
See Figure 2
1000
ns
td1
td2
Delay time, valid data
SCLK↑
SO
CL = 200 pF,
See Figure 3
Delay time, unlatch disable
SIOE↑
CL = 20 pF,
RL = 5 Ω,
tr(SO)
tf(SO)
Rise time
Yn
SO
CL = 200 pF,
See Figure 3
Fall time
SO
CL = 200 pF,
See Figure 3
RL = 28 Ω,
IOL = 500 mA,
IOL = 500 mA,
td(on)
Delay time, turn on
SIOE↑
Yn
CL = 20 pF,
See Figure 5
td(off)
Delay time, turn off
SIOE↑
Yn
CL = 20 pF,
See Figure 5
RL = 28 Ω,
tv
Valid time, SO output data
remains valid after SCLK high
SCLK↑
SO
CL = 200 pF,
See Figure 3
2–6
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
See Figure 4
75
0
550
ns
450
µs
150
ns
150
ns
10
µs
10
µs
ns
TPIC2802
OCTAL INTELLIGENT-POWER SWITCH
WITH SERIAL INPUT
SLIS013 – APRIL 1992
PARAMETER MEASUREMENT INFORMATION
VIH
RST
10%
10%
VIL
tw(RST)
VIH
SIOE
10%
10%
tsu1
tw(SCLKH)
90%
SCLK
90%
10%
tsu3
SI
tr
ÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎÎÎÎ
Don’t Care
90%
10%
VIH
90%
10%
tw(SCLKL)
10%
VIL
ÎÎÎÎÎÎ ÎÎÎÎÎÎ
ÎÎÎÎÎÎ ÎÎÎÎÎÎ
ÎÎÎÎÎÎ ÎÎÎÎÎÎ
tf
th
90% 90%
Valid
10% 10%
VIL
tsu2
VIH
Don’t Care
Valid
Don’t Care
VIL
Figure 1. Input Timing Waveforms
10 ns
5V
10 ns
2.5 V
5V
10
VCC
TPIC2802
9
Under
SO
Test
5
Input
SIOE
GND
RL = 1 kΩ
SIOE
Input
90%
0V
tdis
ten
SO
Output
Waveform 1
(see Note B)
2.5 V
50%
50%
VOL
8
TEST CIRCUIT
FOR ENABLE AND DISABLE TIMES
90%
10%
2.5 V
10%
Output
CL = 20 pF
(see Note A)
2.5 V
ten
SO
Output
Waveform 2
(see Note B)
tdis
VOH
50%
50%
2.5 V
VOLTAGE WAVEFORMS
NOTES: A. CL includes probe and jig capacitance.
B. Waveform 1 is for an output with internal conditions such that the output is low except when disabled by the output control when SIOE
is high. Waveform 2 is for an output with internal conditions such that the low-to-high transition of SIOE causes the output to switch
from off to on.
Figure 2. Test Circuit and Voltage Waveforms for Enable and Disable Times
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
2–7
TPIC2802
OCTAL INTELLIGENT-POWER SWITCH
WITH SERIAL INPUT
SLIS013 – APRIL 1992
PARAMETER MEASUREMENT INFORMATION
5V
Input
10 ns
10
VCC
9
TPIC2802
Under SO
6
Test
SCLK
GND
SCLK
Input
10 ns
10%
8
0V
td1
Output
CL = 200 pF
(see Note A)
5V
90%
50%
tv
SO
Output
Waveform 1
(see Note B)
VOH
90%
10%
VOL
tr(SO)
td1
TEST CIRCUIT
tv
SO
Output
Waveform 2
(see Note B)
VOH
90%
10%
VOL
tf(SO)
VOLTAGE WAVEFORMS
NOTES: C. CL includes probe and jig capacitance.
D. Waveform 1 is for an output with internal conditions such that the low-to-high transition of SCLK causes the SO output to switch from
high to low. Waveform 2 is for an output with internal conditions such that the low-to-high transition of SIOE causes the output to
switch from off to on.
Figure 3. Test Circuit and Voltage Waveforms for Delay Times
5V
15 V
10
Input
5
VCC
TPIC2802
Under
Test
SIOE GND
10 ns
Y
8
TEST CIRCUIT
Output
CL = 20 pF
(see Note B)
10 ns
SIOE
Input
RL = 5 Ω
(see Note A)
90% 90%
50%
50%
10%
Y-Output Voltage
(see Note C)
50%
10%
0V
Voff = 15 V
50%
td2
(see Note D)
Y-Output Current
(see Note C)
5V
Von = 6 V
IO(CL) = 1.8 A
50%
0
VOLTAGE WAVEFORMS
NOTES: A. Load voltage VS and load resistance RL are selected such that on-state voltage at the Y output under test, Von is greater than the
maximum out-of-saturation hold voltage, VTOS. Thus VOL = Von > VTOS(max) = 2.1 V.
B. CL includes probe and jig capacitance.
C. Output voltage and current waveforms are for an output with internal conditions such that the low-to-high transition of SIOE causes
the output to switch from off to on.
D. td2 = delay until Y-output current goes off under fault condition.
Figure 4. Test Circuit and Voltage Waveforms for Unlatch Disable Delay
2–8
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
TPIC2802
OCTAL INTELLIGENT-POWER SWITCH
WITH SERIAL INPUT
SLIS013 – APRIL 1992
PARAMETER MEASUREMENT INFORMATION
14 V
10 ns
5V
SIOE
Input
10
RL = 28 Ω
VCC
Input
5
SIOE
10 ns
TPIC2802
Under
Test
10%
90% 90%
50%
50%
5V
10%
0V
Output
Y
CL = 20 pF
(see Note A)
Y-Output
Waveform 1
(see Note C)
8 GND
td(off)
14 V
50%
VOL
td(on)
14 V
Y-Output
Waveform 2
(see Note C)
TEST CIRCUIT FOR TURN-OFF td(off) AND
TURN-ON td(on) DELAY TIMES (see Note B)
50%
VOL
VOLTAGE WAVEFORMS
NOTES: A. CL includes probe and jig capacitance.
B. td(off) = tPLH, td(on) = tPHL
C. Waveform 1 is for an output with internal conditions such that the low-to-high transition of SIOE causes the output to switch from
on to off. Waveform 2 is for an output with internal conditions such that the low-to-high transition of SIOE causes the output to switch
from off to on.
Figure 5. Test Current and Voltage and Current Waveforms for Turn-Off and Turn-On Delay Times
10 V
5V
IAS = 1 A
IC
10
L = 8 mH
IC
VCC
Input
TPIC2802
Under
5
Test
SIOE
GND
0
Y
Output
V(BR)CEX
VCE
0
8
tav
(b) VOLTAGE AND CURRENT WAVEFORMS
(a) TEST CIRCUIT
Figure 6. Single-Pulse Avalanche Energy Test Circuit and Waveforms
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
2–9
TPIC2802
OCTAL INTELLIGENT-POWER SWITCH
WITH SERIAL INPUT
SLIS013 – APRIL 1992
TYPICAL CHARACTERISTICS
PEAK AVALANCHE CURRENT
vs
TIME DURATION OF AVALANCHE
PEAK AVALANCHE CURRENT
vs
JUNCTION TEMPERATURE
800
1000
tav = 0.5 ms
I AS – Peak Avalanche Current – mA
I AS – Peak Avalanche Current – mA
TJS = 25°C
TJS = 75°C
100
TJS = 125°C
10
TJS = Starting Junction
Temperature
700
tav = 1 ms
600
tav = 3 ms
500
tav = 7 ms
400
300
200
100
0.1
1
10
0
100
0
20 40 60 80 100 120 140 160 180 200
TJS – Starting Junction Temperature – °C
tav – Time Duration of Avalanche – ms
Figure 7
Figure 8
APPLICATION INFORMATION
10
5
7
Microcontroller
With Bus
VCC Y0
SIOE Y1
Y2
SO
Y3
L
14 V ± 0.5 V
3
1
SCLK Y4
11
RST
R
2
SI
9
6
4
Y5
8
15
14
13
GND Y6
12
VCC = 5 V ± 5%
R = 30 Ω ± 5%
L = 45 mH ±10%
8 Loads up to 0.5 A Each
Y7
TPIC2802
Figure 9. Microcontroller Driving Eight Loads Using a TPIC2802 for Load Interface
2–10
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
TPIC2802
OCTAL INTELLIGENT-POWER SWITCH
WITH SERIAL INPUT
SLIS013 – APRIL 1992
PRINCIPLES OF OPERATION
timing data transfer
Figure 10 shows the overall 8-bit data-byte transfer to and from the TPIC2802 interface bus. The logic state of
the eight output drivers, Y0 through Y7, is latched into the shift register at time t0 on the high-to-low transition
of SIOE. Therefore, the SO output data (DY0, DY1 . . . ) represent the conditions at the Y-driver outputs at time
t0. The data at the SO output is updated on the low-to-high transition of SCLK.
Input data present at the SI input is clocked into the shift register on the high-to-low transition of SCLK. As shown
in Figure 10 on the SI input, input data DI7 is clocked at time t1, DI6 is clocked at time t2, etc. Eight SCLK pulses
are used to serially load the eight bits of new data into the device. After all the new data is serially loaded, the
low-to-high transition of SIOE parallel loads the new data to the eight driver output latches, which in turn directly
control the eight Y-driver outputs.
An unlimited amount of data can be shifted through the shift register (into the SI and out the SO), and this allows
other devices to be cascaded in a daisy chain with the TPIC2802. Once the last data bit has been shifted into
the TPIC2802, the SIOE input is pulled high. The clock (SCLK) input is low at both transitions of the SIOE input
to avoid any false clicking of the shift register. The SCLK input is gated by the SIOE input, so the SCLK input
is ignored whenever SIOE is high. At the rising edge of SIOE, the shift register data is latched into the parallel
latch and the output stages are actuated by the new data. An internal 100-µs delay timer is also started on this
rising edge. During the time delay, the outputs are protected only by the analog current-limiting circuits, since
the resetting of the parallel latches by fault conditions are inhibited during this time period. This allows the device
to overcome any high switching currents that can flow during turn-on. Once the delay ends, the output voltages
are sensed by the comparators and any output voltages higher than nominally 1.8 V are latched off.
Time
t0
t1↑
t1↓
t2↑
t2↓
t3↑
t3↓
t4↑
t4↓
t5↑
t5↓
t6↑
t6↓ t7↑
t7↓
t8↑
t8↓
t9↑
H
SIOE
L
H
ÇÇÇ
ÇÇÇ
ÇÇÇ
SCLK
SI
SO
CP1
CP2
DI7
DY7
CP3
DI6
DY6
CP4
DI5
DY5
CP5
DI4
CP6
DI3
DY4
DY3
CP7
DI2
DY2
ÇÇÇÇÇ
ÇÇÇÇÇ
ÇÇÇÇÇ
CP8
DI1
DY1
L
H
DI0
DY0
L
H
HI-Z
L
Y0
Prior (old)
H
DI0 (new)
L
Y1
Prior (old)
H
DI1 (new)
L
Y7
Prior (old)
H
DI7 (new)
L
Figure 10. Data-Byte Transfer Timing
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
2–11
TPIC2802
OCTAL INTELLIGENT-POWER SWITCH
WITH SERIAL INPUT
SLIS013 – APRIL 1992
fault-conditions check
Open-circuit conditions on any output can be monitored or checked by programming that output off. After a short
delay (microseconds), another control byte can be clocked into the device. If the diagnostic bit for that output
comes back low, it indicates that the output is low and open circuited. A current overload condition can be
detected by programming an output on. After waiting an appropriate length of time, another byte is clocked into
the TPIC2802. The diagnostic bit clocked back from the TPIC2802 in the subsequent data transfer indicates
a low output. If a high returns, a current overload is indicated. A quick overall check can be done by clocking
in a test control byte and after a sufficient time delay, clock in another control byte. The diagnostic data is
exclusive ORed with the original control byte. If a fault condition exists, a high results from the subsequent
exclusive OR.
2–12
POST OFFICE BOX 655303
• DALLAS, TEXAS 75265
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