Secondary Side Housekeeping Circuit
Features
•
Standard PC Power Good:
UV Detection on 4 rails
UV Detection of AC/Bulk supply
OV Detection on 4 rails
Open collector PG out
•
Pogrammable Fault output:
OV
OV plus UV
OV plus UV after startup delay
•
OV Crow Bar Driver
•
Digital ON/OFF input
•
2.5V Voltage Reference
•
Operates from 5V or 12V rail
AS23xx
Description
The AS23xx is a housekeeping circuit for monitoring the outputs of power
supplies. It directly senses all the output rails without the need for external dividers
and detects undervoltage and overvoltage. It also provides an additional
undervoltage comparator which may be configured with any arbitrary hysteresis
to sense a divided down representation of the AC bulk voltage. The housekeeping
section provides all the features necessary to allow external caps to set the
common timing features of PC type power supplies. In addition, negative rails may
be sensed without the necessity of a V
EE
connection, and negative sensing may
be disabled without affecting operation of the positive sense section. The 2.5 V
series reference is available and can source up to 5 mA. This IC is available in
16 lead packages. Outputs include a POK (Power OK) and a fault signal.
The AS2333 includes sensing for
±12
V, 5 V, and 3.3V. The AS2350 exchanges
a -5 V sense capability for the 3.3 V input. The AS2316 monitors all supply
voltages, but lacks CBD (Crow-Bar Driver).
Top view
V
CC
+12V
+5V
-5V
-12V
GND
HYST
OFF
1
2
3
4
5
6
7
8
16 CBD
15 FAULT
14 V
REF
13 UVB
12 DELAY
11 POK
10 PGCAP
9
AC
Pin Configuration
—
V
CC
+12V
+5V
+3.3V
-5V
-12V
GND
HYST
1
2
3
4
5
6
7
8
16 FAULT
15 V
REF
14 UVB
13 DELAY
12 POK
11 PGCAP
10 AC
9
OFF
V
CC
+12V
+5V
+3.3V
-12V
GND
HYST
OFF
1
2
3
4
5
6
7
8
16 CBD
15 FAULT
14 V
REF
13 UVB
12 DELAY
11 POK
10 PGCAP
9
AC
AS2316 SOIC
V
CC
+12V
+5V
+3.3V
-5V
-12V
GND
HYST
1
2
3
4
5
6
7
8
16 FAULT
15 V
REF
14 UVB
13 DELAY
12 POK
11 PGCAP
10 AC
9
OFF
AS2333 SOIC
V
CC
+12V
+5V
+3.3V
-12V
GND
HYST
OFF
1
2
3
4
5
6
7
8
16 CBD
15 FAULT
14 V
REF
13 UVB
12 DELAY
11 POK
10 PGCAP
9
AC
AS2350 SOIC
V
CC
+12V
+5V
-5V
-12V
GND
HYST
OFF
1
2
3
4
5
6
7
8
16 CBD
15 FAULT
14 V
REF
13 UVB
12 DELAY
11 POK
10 PGCAP
9
AC
AS2316 PDIP
AS2333 PDIP
AS2350 PDIP
Ordering Information
Package
16-Pin Plastic SOIC
16-Pin Plastic SOIC
16-Pin Plastic SOIC
16-Pin Plastic DIP
16-Pin Plastic DIP
16-Pin Plastic DIP
© ASTEC Semiconductor
Temperature Range
0 to 105° C
0 to 105° C
0 to 105° C
0 to 105° C
0 to 105° C
0 to 105° C
Order Code
AS2316D
AS2333D
AS2350D
AS2316N
AS2333N
AS2350N
91
AS23xx
Functional Block Diagram
V
REF
nUV
Secondary Side Housekeeping Circuit
UV
V
CC
V
CC
GND
+12V
V
CC
R
Latch
S
nUVLatch
Q
nRESET
OV
nO V
t
20 µs delay
nO VLatch
FAULT
UV
R
Latch
Q S
+5V
OV
nFAULT
V
CC
C BD Latch p owers up
in RESET state.
S Q
Latch
UV
+3.3V
nRESET
R
C BD
500
OV
nO V
V
CC
OV
nUV
nUV Latch
1µA
V
REF
V
CC
UVB
UV
- 5V
HYST
V
REF
Disab le
V
CC
1µA
nO V
OV
t
20 µs delay
PGC AP
nPO K
nUV
UV
V
CC
POK
V
REF
- 12V
V
REF
Disab le
V
REF
AC
V
REF
nAC WARNING
nFAULT
V
CC
1µA
DELAY
HYST
V
CC
nRESET
V
REF
2.5V
chip b ias
V
REF
OFF
nO FF WARNING
ASTEC Semiconductor
92
Secondary Side Housekeeping Circuit
Pin Function Description (For AS2333 / AS2350)
Pin Number
Function
Description
AS23xx
1
2
3
4
5
6
7
8
V
CC
+12 V
+5 V
+3.3/–5 V
–12 V
GND
HYST
OFF
Power input to the chip.
Input for overvoltage and undervoltage for the +12 V rail.
Input for overvoltage and undervoltage for the +5 V rail.
Input for overvoltage and undervoltage for the +3.3V rail or –5 V rail, depending on
product option.
Input for overvoltage and undervoltage for the –12 V rail. This function may
disabled by tying this pin to a positive voltage above 2.4 V.
Signal ground and silicon substrate.
Open collector output of the AC undervoltage comparator. A resistor between this pin
and AC will provide hysteresis to the AC undervoltage sensing.
Pulling this pin low will reset the FAULT latch and discharge the start-up timing
capacitors, UVB and PG CAP, allowing normal start-up for the system. Pulling this pin
high will send the FAULT signal high, prompting a system shutdown.
Non-inverting input to the AC undervoltage sensing comparator. If the AC pin is
less than 2.5 V, POK goes low and UVB cap discharges.
A cap to ground provides a delay between undervoltage sensing becoming good
and the POK output going high. Cap discharges whenever an output or AC
undervoltage is detected.
Open collector output of the undervoltage sensing comparators. This pin goes low
upon an undervoltage condition. Except for the delay set by the PG CAP, this pin
always reflects the actual state of the undervoltage sensing.
A cap to ground will delay the FAULT signal when the OFF pin is used to shut down
the system. The POK will signal a power fail warning immediately, but the FAULT
shutdown of the power supply will be delayed.
A cap to ground provides start-up blanking of the undervoltage sensing portion of the
FAULT signal. This pin may also be grounded to prevent undervoltage conditions from
triggering the FAULT signal. This pin discharges the cap whenever AC goes low or
FAULT pin goes high.
2.5 V Voltage reference. This is a series regulator type reference.
Open collector output of the overvoltage and undervoltage comparators.
Crow bar drive output of the overvoltage faults only.
9
10
AC
PG CAP
11
POK
12
DELAY
13
UVB
14
15
16
V
REF
FAULT
CBD
ASTEC Semiconductor
93
AS23xx
Secondary Side Housekeeping Circuit
Pin Function Description (For AS2316)
Pin Number
Function
Description
1
2
3
4
5
6
7
8
9
V
CC
+12 V
+5 V
+3.3
–5 V
–12 V
GND
HYST
OFF
Power input to the chip.
Input for overvoltage and undervoltage for the +12 V rail.
Input for overvoltage and undervoltage for the +5 V rail.
Input for overvoltage and undervoltage for the +3.3V rail.
Input for overvoltage and undervoltage for the –5 V rail.
Input for overvoltage and undervoltage for the –12 V rail. This function may
disabled by tying this pin to a positive voltage above 2.4 V.
Signal ground and silicon substrate.
Open collector output of the AC undervoltage comparator. A resistor between this pin
and AC will provide hysteresis to the AC undervoltage sensing.
Pulling this pin low will reset the FAULT latch and discharge the start-up timing
capacitors, UVB and PG CAP, allowing normal start-up for the system. Pulling this pin
high will send the FAULT signal high, prompting a system shutdown.
Non-inverting input to the AC undervoltage sensing comparator. If the AC pin is
less than 2.5 V, POK goes low and UVB cap discharges.
A cap to ground provides a delay between undervoltage sensing becoming good
and the POK output going high. Cap discharges whenever an output or AC
undervoltage is detected.
Open collector output of the undervoltage sensing comparators. This pin goes low
upon an undervoltage condition. Except for the delay set by the PG CAP, this pin
always reflects the actual state of the undervoltage sensing.
A cap to ground will delay the FAULT signal when the OFF pin is used to shut down
the system. The POK will signal a power fail warning immediately, but the FAULT
shutdown of the power supply will be delayed.
A cap to ground provides start-up blanking of the undervoltage sensing portion of the
FAULT signal. This pin may also be grounded to prevent undervoltage conditions from
triggering the FAULT signal. This pin discharges the cap whenever AC goes low or
FAULT pin goes high.
2.5 V Voltage reference. This is a series regulator type reference.
Open collector output of the overvoltage and undervoltage comparators.
10
11
AC
PG CAP
12
POK
13
DELAY
14
UVB
15
16
V
REF
FAULT
ASTEC Semiconductor
94
Secondary Side Housekeeping Circuit
Absolute Maximum Ratings
Parameter
Symbol
Rating
AS23xx
Unit
Supply Voltage
Continuous Power Dissipation at 25° C
Junction Temperature
Storage Temperature Range
Lead Temperature, Soldering 10 Seconds
V
CC
P
D
T
J
T
STG
T
L
20
1000
150
– 65 to 150
300
V
mW
°C
°C
°C
Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent damage to the device. This is a stress
rating only and functional operation of the device at these or any other conditions above indicated in the operational sections of this
specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability.
Recommended Conditions
Parameter
Supply Voltage
Symbol
V
CC
Rating
5 - 12
Unit
V
Typical Thermal Resistance
Package
16L SOIC
16L PDIP
θ
JA
65° C/W
80° C/W
θ
JC
45° C/W
35° C/W
Typical Derating
10.0 mW/°C
12.5 mW/°C
Electrical Characteristics
Electrical Characteristics are guaranteed over full junction temperature range (0 to 105° C). Ambient temperature must be derated
based on power dissipation and package thermal characteristics. Unless otherwise specified, the conditions of test are V
CC
= 12 V;
+3.3 V = 3.3 V; +5 V = 5V; +12 V = 12 V; –12 V = –12 V; – 5 V = – 5 V; OFF = low.
Parameter
Bias
Supply Current
Min. V
CC
for operation
Undervoltage, Overvoltage
+3.3 V (Not available on AS2350)
+3.3 V Undervoltage
+3.3 V Overvoltage
+3.3 V Input Current
+5 V
+5 V Undervoltage
+5 V Overvoltage
+5 V Input Current
+12 V
+12 V Undervoltage
+12 V Overvoltage
+12 V Input Current
UV
OV
I
B
V
+12
=+12.0V
10.25
14.53
10.50
14.90
0.8
10.60
15.27
1.5
V
V
mA
UV
OV
I
B
V
+5
=+5.0V, V
+3.3
=+3.3V
4.40
5.74
4.50
5.89
1.6
4.60
6.04
2.5
V
V
mA
UV
OV
I
B
V
+3.3
=+3.3V, V
+5
=+5.0V
2.87
3.76
-0.1
2.95
3.86
0
3.03
3.96
0.1
V
V
mA
I
CC
V
CC
Min.
no faults
V
REF
= 2.5 V, no faults
8
12
4.2
mA
V
Symbol
Test Condition
Min
Typ
Max
Unit
ASTEC Semiconductor
95
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