TI UC37133

UC17131/2/3
UC27131/2/3
UC37131/2/3
Smart Power Switch
FEATURES
DESCRIPTION
• 300mA Continuous Output Current
The UC37131, UC37132 and UC37133 are a family of smart power
switches which can drive resistive or inductive loads from the high side or
low side.
• Low Side or High Side Switch
Configuration
• 8V to 65V Operation
• Overload and Short Circuit Protection
• Power Interruption Protection
• +6V Regulated Voltage
• 2mA Quiescent Current
• Programmable Overcurrent and
Power Interruption Protection
The UC37132 is available in 14 pin (DIP), 16 pin (SOIC), or 20 pin (CLCC)
packages and can accommodate both low side (load to VCC) or high side
(load to GND) configurations. The UC37131 and UC37133 are exclusively
for a low side or a high side configuration respectively and both are available in an 8 pin package. Both high side and low side configurations provide
high current switching with low saturation voltages which can drive resistive
or inductive loads.
The input to the switch is driven by a low voltage signal, typically 5V. Additionally, UC37132 features adjustable hysteresis. The output of the device
can switch a load between 8V and 65V. Output current capability is 300mA
continuous or 700mA peak.
• 1% to 30% Programmable Input
Comparator Hysteresis (on UC37132) The device also has inherent smart features that allow for programmable
turn-on delay in enabling the output following startup. The same capacitor
• Low and High Side Internal High
that specifies the turn-on delay is also used to program a VCC power interCurrent Clamps When Driving
ruption time. If VCC drops below a threshold for a time specified by this caInductive Loads
pacitor, the output is turned off and a new turn-on delay will be re-triggered.
Similarly, if high current persists longer than the response delay, the output
driver will operate in a very low duty cycle mode to protect the IC.
UC37132 BLOCK DIAGRAM
VREF
6V
PRE-REGULATOR
11
7
VCC
6
CSH
5
LS
4
HS
3
CSL
2
GND
6V/8mA
IN
INPUT
COMPARATOR
13
72V
Q OUT
TURN-ON/OFF
AND
SHORT CIRCUIT
PROTECTION
1/2
VREF
12
9
10
HYST
LED
CDEL
UDG-98026
SLUS340 - APRIL 1999
UC17131/2/3
UC27131/2/3
UC37131/2/3
UC37131 BLOCK DIAGRAM
VREF
6V
PRE-REGULATOR
3
8
VCC
7
LS
6
CSL
5
GND
6V/8mA
INPUT
COMPARATOR
4
IN
72V
HYST (FIXED) =
30%
Q OUT
TURN-ON/OFF
AND
SHORT CIRCUIT
PROTECTION
1/2
VREF
1
2
LED
CDEL
UDG-98059
UC37133 BLOCK DIAGRAM
VREF
6V
PRE-REGULATOR
3
8
VCC
7
CSH
6
HS
5
GND
6V/8mA
IN
INPUT
COMPARATOR
4
HYST (FIXED) =
30%
72V
Q OUT
TURN-ON/OFF
AND
SHORT CIRCUIT
PROTECTION
1/2
VREF
1
2
LED
CDEL
UDG-98060
2
UC17131/2/3
UC27131/2/3
UC37131/2/3
CONNECTION DIAGRAMS
ABSOLUTE MAXIMUM RATINGS
VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65V
LS – HS (Clamped by internal circuitry) . . . . . . . . . . . . . . . 78V
CSH, LED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65V
Output Current
Continuous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400mA
Peak . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 900mA
Remaining Pin Voltages . . . . . . . . . . . . . . . . . . . . . –0.3V to 9V
Storage Temperature . . . . . . . . . . . . . . . . . . . −65°C to +150°C
Junction Temperature . . . . . . . . . . . . . . . . . . . –55°C to +150°C
Lead Temperature (Soldering, 10 sec.) . . . . . . . . . . . . . +300°C
SOIC-16 (Top View)
(for UCX7132)
D Package
Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and considerations of packages.
PLCC-20 (Top View)
(for UCX7132)
L Packages
N/C
1
16
N/C
GND
2
15
IN
CSL
3
14
HYST
HS
4
13
VREF
LS
5
12
CDEL
CSH
6
11
LED
N/C
7
10
N/C
VCC
8
9
N/C
N/C
LS
CSH
HS
CSL
3
2
1
N/C
4
18
N/C
VCC
5
17
GND
N/C
6
16
N/C
N/C
7
15
N/C
N/C
8
14
9
DIL-8, SOIC-8 (Top View)
(for UCX7131)
J, N, or D Packages
20 19
LED
1
8
VCC
IN
CDEL
2
7
LS
HYST
VREF
VREF
3
6
CSL
IN
4
5
GND
10 11 12 13
N/C
LED
CDEL
DIL-14 (Top View)
(for UCX7132)
J, or N Packages
DIL-8, SOIC-8 (Top View)
(for UCX7133)
J, N, or D Packages
N/C
1
14
N/C
GND
2
13
IN
CSL
3
12
HYST
LED
1
8
VCC
HS
4
11
VREF
CDEL
2
7
CSH
LS
5
10
CDEL
VREF
3
6
HS
CSH
6
9
LED
IN
4
5
GND
VCC
7
8
N/C
PRODUCT SELECTION TABLES
PART
NUMBER
UCX7131
UCX7132
UCX7133
CONFIGURATIONS
Low Side Only
Low Side or High Side
High Side Only
PACKAGE
PIN COUNT
8
14, 16, 20
8
PART
NUMBER
UC1713X
UC2713X
UC3713X
3
TEMPERATURE
RANGE
–55°C to +125°C
–40°C to +85°C
0°C to +70°C
AVAILABLE
PACKAGES
J, L
D, N
D, N
UC17131/2/3
UC27131/2/3
UC37131/2/3
ELECTRICAL CHARACTERISTICS Unless otherwise specified, CDEL = 10nF, VCC = 25V, CSL = GND, CSH = LS;
RCSH = 0.5Ω (Note 1); IN=0V (for OFF condition) and IN=5V (for ON condition); TA = TJ.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX UNITS
25°C
5.8
6
6.2
V
–55°C to 125°C
5.6
6
6.4
V
Reference
VREF
Line Regulation
VCC = 8V to 64V
10
35
mV
Load Regulation
0 < IREF < 8mA
10
50
mV
Short Circuit Current
REF = 0V
20
35
mA
3
3.3
V
5
µA
Input Comparator
Turn-On Threshold Voltage
2.7
Input Bias Current
VIN = 3.5V
Hysteresis
RHYST = GND (Internally for X31, X33)
0.775
RHYST = 96.67k for (X32)
0.9
1.025
30
V
mV
Output: High Side (UCX7133: CSH = LS and CSL = GND Internally; See Fig. 2a)
Rise Time (Off to On)
RLOAD = 250Ω to GND
30
Fall Time (On to Off)
RLOAD = 250Ω to GND
Output Short Circuit
HS = 0.25Ω to GND
500
Voltage Clamp
LS–HS
67
77
V
Saturation Voltage
25°C, RLOAD = 100Ω to GND
1.2
V
–40°C, RLOAD = 100Ω to GND
1.3
V
–55°C, RLOAD = 100Ω to GND
1.4
V
5
µA
30
72
Leakage Current
80
V/µs
80
V/µs
900
mA
Output: Low Side (UCX7131; CSH = VCC and CSL = HS Internally; See Fig. 2b)
Rise Time (On to Off)
RLOAD = 250Ω to VCC, RCSL = 0.5Ω
15
50
V/µs
Fall Time (Off to On)
RLOAD = 250Ω to VCC, RCSL = 0.5Ω
25
60
V/µs
Output Short Circuit
LS = 0.25Ω to VCC
500
700
900
mA
Voltage Clamp
LS–HS
67
72
77
V
Saturation Voltage
25°C, RLOAD = 100Ω to VCC, RCSL = 0.5Ω
1.2
V
–40°C, RLOAD = 100Ω to VCC, RCSL = 0.5Ω
1.3
V
–55°C, RLOAD = 100Ω to VCC, RCSL = 0.5Ω
1.4
V
5
µA
Leakage Current
VCC Fault Section
Output Turn-On Delay, tD(ON)
Step VCC from 0V to 8V (See Fig. 3a)
9.5
11
13.5
ms
Output Turn-Off Delay, tD(OFF)
Pulse VCC from 25V to VCC Turn-Off
Threshold
300
500
700
µs
VCC Turn-Off Threshold
Pulse VCC Low
6.5
7
7.5
V
CDEL Section
VCDEL_MAX
5.8
V
VFAULT_H
4.9
V
VFAULT_L
1.0
V
75
µs
Overcurrent Fault Section (See Fig. 3c)
Short Circuit Turn-Off Delay, tSC
Step ILOAD: 0mA to 400mA
Short Circuit Recovery Time, tROFF
ILOAD = 400mA, 100µs
High Side Current Threshold, ITH-H
RCSH = 0.5Ω
250
325
400
mA
Low Side Current Threshold, ITH-L
RCSL = 0.5Ω
250
325
400
mA
Overcurrent Duty Cycle
RLOAD = 0.25Ω to GND
0.6
0.8
1.0
%
4
10
ms
UC17131/2/3
UC27131/2/3
UC37131/2/3
ELECTRICAL CHARACTERISTICS Unless otherwise specified, CDEL = 10nF, VCC = 25V, CSL = GND, CSH = LS;
RCSH = 0.5Ω (Note 1); IN=0V (for OFF condition) and IN=5V (for ON condition); TA = TJ.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX UNITS
5.0
8.0
11.0
mA
1
5
µA
3
6
µs
LED Output
ISINK, tDOFF, tROFF
VLED = 7V
ILEAKAGE
Overall
Delay to Output
ICC
Output Off
2.0
2.8
mA
IL = 1mA, 250mA (High Side)
2.3
3
mA
IL = 1mA, 250mA (Low Side)
2.5
4
mA
Note 1: All test conditions are for a high side configuration as in Fig. 2a, unless otherwise specified.
PIN DESCRIPTIONS
HS: (For UC37132 and UC37133) The output of the
switching transistor in the high side configuration. The
emitter of the output transistor is the HS pin which is connected to the load. For the UC37132, the HS pin must be
tied to the CSL pin in a low side application.
CDEL: A capacitor connected to this pin is used to program both VCC pulse interruption time and power
turn-on delay. The capacitor discharge time corresponds
to VCC interruption and the charge time to VCC turn-on
delay. The ratio between turn-on delay and turn-off delay
will be fixed based on internal charge and discharge currents and voltage thresholds.
HYST: (For UC37132) The pin used to program the input comparator hysteresis by connecting a resistor to
ground. The hysteresis defaults to 30% with HYST
grounded (internally for UC37131 and UC37133).
The same fault circuitry and capacitor is used for short
circuit and overload protection. If an overcurrent or short
circuit is detected, the capacitor starts charging and
turns off the output if the condition persists at the end of
its charge time. The output will then operate in a low-duty
cycle mode to protect the IC. After short circuit recovery,
the output will be reactivated in order to check if the short
circuit was removed. If the overcurrent persists the chip
will continue in this pulsing mode.
V HYST =
3000
(3330 + R HYST )
IN: The input to the comparator that detects when the
output transistor should be turned on. The input threshold is 3.0V (1/2 VREF) and the input voltage range is 0V
to VREF.
CSH: (For UC37132 and UC37133) This high side current sense pin is used to program the current limit for
high side applications by connecting a resistor between
VCC and CSH. An over load current is detected when
the voltage drop between VCC and CSH exceeds
150mV. For the UC37132, in a high side application, the
CSH pin must be tied to the LS pin; in a low side application, the CSH pin must be tied to VCC
LED: Open collector output intended to drive an LED.
This pin is driven low whenever the output is turned off
and is externally pulled high when the output is turned on
(see Fig. 3b and 3c).
LS: (For UC37131 and UC37132) The output of the
switching transistor in the low side configuration. The collector of the output transistor is the LS pin which is connected to the load. For the UC37132, the LS pin must be
tied to the CSH pin in a high side application.
CSL: (For UC37131 and UC37132) This low side current sense pin is used to program the current limit for low
side applications by connecting a resistor between CSL
and GND. An over load current is detected when the voltage drop between CSL and GND exceeds 150mV. For
the UC37132, in a high side application, the CSL pin
must be tied to GND; in a low side application, the CSL
pin must be tied to the HS pin.
VREF: The 6V regulated reference capable of supplying
up to 8mA. The recommended decoupling capacitor is
1nF.
VCC: The supply voltage for the chip. Decouple this pin
with a good quality ceramic capacitor to ground.
GND: The reference point for the internal reference, all
thresholds, and the return for the remainder of the device.
5
UC17131/2/3
UC27131/2/3
UC37131/2/3
DESCRIPTION OF OPERATION
Reference
current of approximately 4µA. If the power stays off longer than this time, then a power up delay will be initialized once power is resumed. This delay is the time it
takes for CDEL to charge from 0V to VFAULT_H of 4.9V.
The UC37131/2/3 family of devices features a 6V
bandgap reference that is used to bias on-chip logic. Although the 6V reference is not trimmed, this bandgap reference provides less than 200ppm/°C. It is also used to
generate the on-chip 3V input comparator threshold and
is needed for the programmable hysteresis. The on-chip
reference has 8mA maximum current sourcing capacity
that is designed to power up external circuitry.
The overcurrent fault normal operation consists of the
chip staying off until CDEL fully recharges to VFAULT_H of
4.9V. This is tR(OFF). Once CDEL reaches 4.9V, the driver
will turn back on. If the overcurrent fault is still present,
the chip will operate in a very low duty cycle (approximately 0.7%) based on the discharge (driver on) and
charge time (driver off) of the CDEL capacitor. This
overcurrent timing makes the chip act "smart" by allowing
very high currents needed to drive large capacitive loads
without setting off an overcurrent fault.
Input Comparator
The input comparator is a high gain comparator with hysteresis that fully switches with either a small signal
(30mV, minimum for 1% hysteresis) or a logic signal (0 to
6V max). Only a 5mV overdrive of the 3V threshold is
needed to switch the driver.
The overcurrent and current limit thresholds are programmed with the resistor RCSH from CSH to VCC (high
side) or RCSL from CSL to GND (low side). For example,
a 150mV (ILOAD • RCSH) threshold will set the high side
overcurrent fault threshold. An overall short circuit protection threshold is set at 300mV. Therefore, the recommended RCSH of 0.5Ω will result in the 600mA short
circuit. By changing the RCSH value the user can optimally set the overcurrent and short circuit current limits.
The hysteresis is set to 30% on the UC37131 and
UC37133. (This is 30% of 3V equating to 0.9V of hysteresis.) On the UC37132 it is programmable from 1% to
30%.
Fault Logic
The output of the comparator is logic ANDed with the
output of the fault logic. If a fault, either a power interrupt
or an overcurrent condition, persists longer than it takes
for the CDEL to discharge from its VCDEL_MAX level of
5.8V to its VFAULT_L of 1.3V, the fault protection block will
output a logic 0 to the NAND gate and turn off the output
driver. If the fault goes away prior to CDEL being discharged to 1.3V, the chip will resume normal operation
without going through a turn-on delay.
Output Driver
Once the turn-on signal is gated through from the input
comparator, the output transistor is turned on. The output
drive transistor is a composite PNP, NPN structure. This
is a specially designed structure that keeps all the drive
current needed for the load to be sourced through the LS
pin. This keeps the overall power dissipation to less than
4mA independent of the load.
The power interrupt normal operation consists of the chip
turning the driver immediately back on if the interrupt
goes away prior to CDEL reaching its lower threshold as
described above. The CDEL capacitor is chosen based
upon the maximum power interrupt time (tINT) allowed
without the output experiencing a turn-on delay. This interrupt time must be less than tD(OFF) where tD(OFF) is
equal to the time it takes the CDEL capacitor to discharge from VCDEL_MAX (5.8V) to VFAULT_L (1.3V) with a
discharge current of approximately 94µA. If the power
stays off only as long as tD(OFF), the minimum power up
delay will be equal to the time it takes to charge CDEL
from VFAULT_L (1.3V) to VFAULT_H (4.9V) with a charge
The output driver also has a 72V zener diode wired between its base and collector. This allows the output to
swing and clamp to 72V above ground when discharging
an inductive load in a low side application. The inductive
zener clamp can discharge the 250mA to 400mA full
load current. This consequently allows the LS pin to
safely swing above VCC. Similarly, the 72V zener diode
will allow the HS pin to safely swing and clamp 72V below LS/VCC when discharging an inductive load in a high
side application. This 72V zener diode simplifies the user
application by eliminating the need for external clamp diodes.
6
UC17131/2/3
UC27131/2/3
UC37131/2/3
APPLICATION INFORMATION
ence an indeterminate state during this interruption, but
resume normal operation when VCC power returns to
normal.
Choosing The CDEL Capacitor
The maximum amount of time that VCC power can be interrupted and not require the outputs to go through a
turn-on delay cycle is user programmable by the CDEL
capacitor value. While VCC is interrupted, the outputs
will be in an indeterminate state and they may turn off
during this interval, tINT. However, as long as the programmed interruption time is not exceeded, the outputs
will immediately turn back on with the return of VCC.
If the VCC power is interrupted for a time equal to or longer than tD(OFF) then the following relationships apply.
As the CDEL capacitor discharges past the VFAULT_L
threshold, the output is fully disabled and must cycle
through a power up delay equal to tD(ON). The charge
current for the CDEL capacitor is equal to 4µA. The outputs will turn on when the CDEL capacitor charges up to
the VFAULT_H threshold of 4.9V. The minimum turn-on
delay the outputs will experience will occur if tINT is exactly equal to the tD(OFF) time and the CDEL capacitor
has only discharged to VFAULT_L. This would be the minimum turn-on delay time and is calculated with the following equation:
For example:
t INT ≈ 500µs (User specified)
CDEL is selected such that the time it takes for this capacitor to discharge from VCDEL_MAX (5.8V) to VFAULT_L
(1.3V) with a discharge current of 94µA is just greater
than this tINT. This time is referred to as tD(OFF) in Fig.
3b.
CDEL =
t D (ON )
I DISCHARGE • t D (OFF )
VCDEL _MAX − V FAULT _L
CDEL • V FAULT _L − V FAULT _H
ICHARGE
Using the 10nF CDEL capacitor, for example, the minimum turn-on delay calculates to 9ms. If the CDEL capacitor discharges completely to zero, then the 10nF
CDEL capacitor would cause a turn-on delay of 12.25ms.
The outputs would be off for this amount of time after
VCC power is restored. The total amount of time the outputs could be disabled is equal to the tINT time, which
may include the indeterminate time of tD(OFF), and the
tD(ON) time, as shown in Fig. 3b.
If tD(OFF) is set equal to tINT, which the user has selected
to be 500µs, the minimum CDEL capacitor is calculated:
CDEL =
min
=
94µA • 500µs
58
. V − 13
.V
For this application, the CDEL capacitor value calculates
to 10.4nF. By using a 10nF capacitor on CDEL, VCC can
be interrupted for up to 478µs and the outputs will experiVREF
6V
PRE-REGULATOR
11
7
VCC
ICC
CREF
6
+L
RCSH
CSH
POWER
SUPPLY
LS
5
IN
INPUT
COMPARATOR
13
72V
CCC
VREF
Q OUT
GND
HS
4
1/2
VREF
TURN-ON/OFF
AND SHORT
CIRCUIT
PROTECTION
OUT
LOAD
CSL
3
2
GND
–L
IGND
12
9
HYST
LED
R
10
CDEL
CCDEL
HYST
UDG-98027
Figure 2a. High side application.
7
UC17131/2/3
UC27131/2/3
UC37131/2/3
APPLICATION INFORMATION (cont.)
VREF
VCC
6V
PRE-REGULATOR
11
7
+L
ICC
CREF
6
CSH
CCC
LOAD
LS
5
IN
INPUT
COMPARATOR
13
OUT
72V
POWER
SUPPLY
VREF
Q OUT
GND
HS
4
TURN-ON/OFF
AND SHORT
CIRCUIT
PROTECTION
1/2
VREF
CSL
3
RCSL
2
GND
–L
IGND
12
HYST
9
10
LED
CDEL
CCDEL
RHYST
UDG-98028
Figure 2b. Low side application.
tINT
VCC
t
VCDEL_MAX = 5.8V
VCDEL
VFAULT_H
VFAULT_H = 4.9V
t
OUTPUT
DRIVER
tD(ON)
DISABLED
ENABLED
ENABLED
t
INDETERMINATE
STATE
UDG-98029
Figure 3a. Power interrupt ignore operation, high side configuration, VIN = 5VDC.
8
UC17131/2/3
UC27131/2/3
UC37131/2/3
APPLICATION INFORMATION (cont.)
tINT
VCC
t
VCDEL_MAX = 5.8V
VCDEL
VFAULT_L = 1.0V
VFAULT_H
VFAULT_H = 4.9V
t
tD(OFF)
tD(ON)
tD(ON)
OUTPUT
DRIVER
DISABLED
DISABLED
ENABLED
ENABLED
t
t
LED
INDETERMINATE
STATE
UDG-98030
Figure 3b. Power interrupt fault operation, high side configuration, VIN = 5VDC.
ILOAD
t
4.9V
VCDEL
t
tSC
OUTPUT
DRIVER
t
tR(OFF)
LED
t
UDG-98031
Figure 3c. Overcurrent fault operation.
UNITRODE CORPORATION
7 CONTINENTAL BOULEVARD • MERRIMACK, NH 03054
TEL (603) 424-2410 • FAX (603) 424-3460
9
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