BLOCK DIAGRAM
Note: Pin Numbers refer to J, N, and DW Packages.
4/97
The UC1904 Quad Supply Monitor will respond to under- and over-volt-
age conditions on up to four continuously monitored voltage levels. Four
independent positive voltages can be monitored or, alternatively, two of
the sense inputs are preset to monitor -5V and -12V supplies. The de-
vice also monitors Over-Current and Line Sense inputs, both with preci-
sion input thresholds.
Four open collector outputs on the UC1904 give the following re-
sponses: 1. The OV/OC output is a latched over-voltage, or over-current
response. 2. A Power Good signal responds low with any fault detection
on power-up a programmable delay is used to hold this output low for
a system Power On Reset signal. 3. The PWRW output responds only to
a Line Sense input, for early warning of power failures. 4. The last open
collector, the ON/OFF output, generates a delayed supply OFF control
signal in response to an OFF input command, under-voltage condition,
or line fault detection.
The OV-UV fault window is adjustable with a programming input. The
thresholds are centered around the precision 2.5V reference, with a
scaled hysteresis for precise, glitch free operation. In the positive mode
of operation, the fault windows at each of the sense inputs can be inde-
pendently scaled using external resistors and the 2.5V reference output.
An Auto Restart function couples with the under-voltage and line sens-
ing circuits to allow controlled power supply start-up and shutdown.
This device will operate over a supply range of 4.75V to 18V. The device
is available in a DIP, SOIC, or PLCC outline. This device is ESD pro-
tected on all pins.
Inputs for Monitoring Up to Four
Supply Voltages
Two Inputs Preset for -5V and -12V
Monitoring, or Programmable
Positive Levels
Precision 2.5V Reference
Separate Inputs for Over-Current and
Line Fault Sensing
Adjustable Under- to Over-Voltage
Fault Windows
Latched Over-Voltage and
Over-Current Output
Power Good and Power Warning
Outputs
Auto Restart Function with ON/OFF
Control, and Programmable Delay
Programmable Pwr On Reset Delay
UC1904
UC2904
UC3904
Precision Quad Supply and Line Monitor
FEATURES
DESCRIPTION
UC1904
UC2904
UC3904
Input Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20V
Sense Inputs, S1 And S2, Other Analog And Logic Inputs
Maximum Forced Voltage . . . . . . . . . . . . . . . . . . -0.3V to 10V
Maximum Forced Current . . . . . . . . . . . . . . . . . . . . . .
10mA
Sense Input S3, (-12V Sense Input)
Maximum Forced Voltage . . . . . . . . . . . . . . . . . . -18V to 10V
Maximum Forced Current . . . . . . . . . . . . . . . . . . . . . .
10mA
Sense Input S4, (-5V Sense Input)
Maximum Forced Voltage . . . . . . . . . . . . . . . . . . -10V to 10V
Maximum Forced Current . . . . . . . . . . . . . . . . . . . . . .
10mA
Open Collector Outputs
Maximum Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20V
Maximum Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50mA
Reference Output Current . . . . . . . . . . . . . . . Internally Limited
Operating Junction Temperature . . . . . . . . . . . -55
C to +150
C
Storage Temperature . . . . . . . . . . . . . . . . . . . . -65
C to +150
C
PACKAGE PIN FUNCTION
FUNCTION
PIN
2.5V
1
POR DLY
2
N.C.
3
S1
4
S2
5
S3
6
S4
7
N.C.
8
LS Input
9
OC Input
10
PWRW Out
11
PG Out
12
OV/OC Out
13
V
IN
14
ON/OFF Out
15
OFF DLY
16
ON/OFF Input
17
ARST Input
18
W
ADJ
19
Gnd
20
DIL-18, SOIC-18 (TOP VIEW)
J or N PACKAGE, DW PACKAGE
PLCC-20 (TOP VIEW)
Q PACKAGE
CONNECTION DIAGRAMS
ABSOLUTE MAXIMUM RATINGS (Note 1)
Note 1: Unless otherwise indicated, voltages are reference to
ground and currents are positive into, negative out of, the speci-
fied terminals.
Unless otherwise stated, these specifications hold for T
A
= 0 to 70
C for the
UC3904, -40 to +85
C for the UC2904, and -55 to +125
C for the UC1904, +V
IN
=
15V, W
ADJ
= 0.5V, Sense Inputs 1-4, OC and LS Inputs = 2.5V. The ON/OFF Input
and the ARST Input = 0V.
ELECTRICAL CHARACTERISTICS:
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
Input Supply
V
IN
Supply Current
V
IN
= 15V
3.2
4.5
mA
V
IN
UVLO Threshold
Low to High
4.5
4.75
V
UVLO Threshold Hysteresis
50
mV
Minimum V
IN
to Enable PG Out
0.8
1.5
V
Reference
Output Voltage(V
REF
)
T
J
= 25
C
2.475
2.5
2.525
V
Over Temperature, UC3904
2.47
2.53
V
Over Temperature, UC2904 & UC1904
2.465
2.535
V
Load Regulation
I
OUT
= 0 to 4mA
6
mV
Line Regulation
V
IN
= 4.75 to 18V
5
mV
Short Circuit Current
V
REF
= 0V
17
mA
OV UV Window, LS Input, OC Input, ARST Input, and ON/OFF Input Thresholds
Over-Voltage Thresholds
W
ADJ
= 0.25V, Offset from V
REF
, Input L to H
110
125
140
mV
S1, S2
W
ADJ
= 0.5V, Offset from V
REF
, Input L to H
230
250
270
mV
W
ADJ
= 1V, Offset from V
REF
, Input L to H
460
500
540
mV
Over-Voltage Thresholds
W
ADJ
= 0.25V, Offset from V
REF
, Input L to H
110
125
145
mV
S3, S4 Positive Mode
W
ADJ
= 0.5V, Offset from V
REF
, Input L to H
230
250
280
mV
W
ADJ
= 1V, Offset from V
REF
, Input L to H
460
500
550
mV
2
UC1904
UC2904
UC3904
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
OV UV Window, LS Input, OC Input, ARST Input, and ON/OFF Input Thresholds (cont.)
Under-Voltage Thresholds
W
ADJ
= 0.25V, Offset from V
REF,
Input H to L
-140
-125
-110
mV
S1, S2
W
ADJ
= 0.5V, Offset from V
REF,
Input H to L
-270
-250
-230
mV
W
ADJ
= 1V, Offset from V
REF,
Input H to L
-540
-500
-460
mV
Under-Voltage Thresholds
W
ADJ
= 0.25V, Offset from V
REF,
Input H to L
-150
-125
-110
mV
S3, S4 Positive Mode
W
ADJ
= 0.5V, Offset from V
REF,
Input H to L
-285
-250
-230
mV
W
ADJ
= 1V, Offset from V
REF,
Input H to L
-555
-500
-460
mV
OV and UV Threshold Hysteresis As a Function of W
ADJ
30
50
70
mV/V
S3 Negative Mode Thresholds
Over-Voltage, W
ADJ
= 0.5V, Input H to L
-13.52
-13.2
-12.88
V
Under-Voltage, W
ADJ
= 0.5V, Input L to H
-11.06
-10.8
-10.54
V
Hysteresis, W
ADJ
= 0.5V
80
120
160
mV
S4 Negative Mode Thresholds
Over-Voltage, W
ADJ
= 0.5V, Input H to L
-5.63
-5.5
-5.37
V
Under-Voltage, W
ADJ
= 0.5V, Input L to H
-4.61
-4.5
-4.39
V
Hysteresis, W
ADJ
= 0.5V
30
50
70
mV
W
ADJ
Input Bias Current
0.25V < W
ADJ
<1.0V
-5
5
A/V
LS Threshold
Input = H to L
1.96
2
2.04
V
Threshold hysteresis
65
100
125
mV
OC Threshold
Input = H to L
1.9
2
2.1
V
Threshold hysteresis
50
100
150
mV
ARST Input Threshold
Input = L to H
2.25
2.5
2.75
V
Input = H to L
0.56
0.625
0.69
V
ON/OFF Input Threshold
Input high level
1.74
2.4
V
Input low level
0.6
1.35
V
Sense and Logic Input Bias Currents
Sense 1-4, Positive Mode
Input = 2.8V
250
800
nA
Input = 2.2V
-1000
-250
nA
Sense 3 Negative Mode
Input = -12V
-700
-500
-300
A
Sense 4 Negative Mode
Input = -5V
-700
-500
-300
A
Line, and OC Inputs
Input = 2.2V
300
1000
nA
ON/OFF Input
Input = 2.5V
150
600
nA
ARST Input
Input = 0.5
-2000
-700
nA
Open Collector Outputs (OV/OC Out, PG Out, PWRW Out, ON/OFF Out)
Saturation Voltage
I
OUT
= 10mA
0.2
0.4
V
Leakage current
V
OUT
= 20V
5
A
POR Delay
Delay
160
250
350
ms/
F
Internal Pullup Current
9
A
Threshold Low to High
2.25
V
OFF Delay
Delay
120
185
250
ms/
F
Internal Pullup current
12
A
Threshold Low to High
2.25
V
OV Fault Delay
Delay
10
20
50
s
Unless otherwise stated, these specifications hold for T
A
= 0 to 70
C for the UC3904, -40 to
+85
C for the UC2904, and -55 to +125
C for the UC1904, +V
IN
= 15V, W
ADJ
= 0.5V, Sense
Inputs 1-4, OC and LS Inputs = 2.5V. The ON/OFF Input and the ARST Input = 0V.
ELECTRICAL
CHARACTERISTICS (cont):
3
PIN FUNCTIONAL DESCRIPTION
2.5V: This is the output of the precision 2.5V reference.
ARST Input: This input, with a 4:1 hysteretic threshold,
is used to sequence a power system through the Auto
ReStarT cycle. A delayed representation of a supply out-
put voltage is used at this pin to provide adequate startup
time for the power system, and a minimum power-off pe-
riod.
Gnd: Reference point for the internal reference and all
thresholds, as well as the return for the remainder of the
device.
LS Input: The Line Sense input is used to monitor a volt-
age that varies with the input line voltage to a system.
The input is compared to a precision 2.0V level and is
used to activate the PWRW and PG outputs, as well as
triggering the Auto Restart sequence.
OC Input: The Over-Current input can be used to re-
spond to an inverted over-current signal. A low level sig-
nal at this input latches in a fault indication at the OV/OC
output.
OFF DLY: This pin functions similarly to the POR DLY
pin to delay the turn-on of the ON/OFF output transistor.
The charging current and upper threshold are 12
A and
2.1V.
ON/OFF Input: With a high level at this input the
ON/OFF Out pin is activated after a user-programmable
delay. A high level also activates the PG Out pin, and re-
sets the OV/OC fault latch.
On/Off Out: This output is an open collector output that
is activated by the ON/OFF Input, or the Auto Restart cir-
cuitry. Saturation voltage on this and all the open collec-
tor outputs is rated at 10mA of current.
OV/OC Out: In response to either an Over-Voltage or
Over-Current situation this output is latched active low.
There is nominal 20
s delay in the OV path to the fault
latch, providing rejection to transient overshooting on the
monitored voltages. The low condition is cleared when
the fault latch is reset by the ON/OFF Input, or a UVLO
condition on the device.
POR DLY: This pin is used, with an external capacitor, to
program a Power-On-Reset delay. This delay is reset
whenever there is a UV condition at one of the S1-S4 in-
puts, and then triggered upon the clearing of the UV con-
dition. When reset, the voltage across the capacitor is
quickly discharged to near zero volts, and the PG Out pin
goes active low. Once triggered the capacitor is charged
by a 9
A current source. The PG Out pin remains active
low until the delay capacitor voltage reaches a 2.1V
threshold.
PG Out: During any fault, under-voltage, or UVLO condi-
tion this output is low. A Power Good indication (output
off) is given when all supply conditions are within defined
operating limits. During power-up the PG signal is de-
layed by a programmable Power On Reset delay. During
UVLO the output is active low as long as the input sup-
ply, V
IN
, is above approximately 1.0V.
PWRW Out: When a low line condition is sensed by the
LS Input this output goes low. This output is disabled
(off) during a UVLO condition.
S1-S4: These are the sense inputs for OV and UV moni-
toring of external voltages. All four inputs can be used to
sense positive voltages with a simple divider to scale the
voltage level to the 2.5V centered window. The S3 and
S4 inputs can also be used to sense -12V and -5V sup-
plies respectively with no external components. This is
done with internal precision resistor dividers and two
source only op-amps that are disabled when the pins are
used in the positive mode.
V
IN
: Input supply for the UC1904. The device is opera-
tional with 4.75V to 18V on this pin.
W
ADJ
: The W
ADJ
input is used to program the OV and
UV window thresholds. The OV-UV window is centered
around the 2.5V reference and is nominally
20% per
volt on the W
ADJ
input pin.
UC1904
UC2904
UC3904
4
UC1904
UC2904
UC3904
UNITRODE CORPORATION
7 CONTINENTAL BLVD.
MERRIMACK, NH 03054
TEL. (603) 424-2410
FAX (603) 424-3460
Note: Pin Numbers refer to J, N, and DW Packages.
5
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