Standard Products
VRG8691/92
Adjustable 7.5A Positive LDO Regulator
Radiation Tolerant
www.aeroflex.com/voltreg
June 4, 2013
FEATURES
Radiation performance
- Total dose: 100 krads(Si),
Dose rate = 50 - 300 rads(Si)/s
Output voltage adjustable: 1.0V to 3.3V
Output current: 7.5A
Dropout voltage: 0.5V at 7.5Amps
Voltage reference: 1.0V ±0.5%
Load regulation: 0.5% max
Line regulation: 0.2% max
Ripple rejection: >80dB
Enable Input - TTL / CMOS Compatible
Slow Start capability
Stable with multiple ceramic output capacitors
Packaging – Hermetic metal
- Thru-hole or Surface mount
- 12 Leads, 0.900"L x 1.000"W x .205"Ht
- Power package
- Weight - 18 gm max
Designed for aerospace and high reliability space
applications
Aeroflex Plainview’s Radiation Hardness Assurance Plan is DLA Certified to MIL-PRF-38534, Appendix G.
DESCRIPTION
The Aeroflex Plainview VRG8691/92 is capable of supplying in excess of 7.5Amps over the output voltage range as
defined under recommended operating conditions. The regulator is exceptionally easy to set-up, requiring only 2
external resistors to set the output voltage. The module design has been optimized for excellent regulation and low
drop-out voltage. Figures 2 through 5 illustrate setting output voltage, setting current limits and choosing a slow start
capacitor. The VRG8691/92 serves a wide variety of applications including local on-card regulation, programmable
output voltage regulation or precision current regulation.
The VRG8691/92 has been specifically designed to meet exposure to radiation environments. The VRG8691 is
configured for a Thru-Hole 12 lead metal power package and the VRG8692 is configured for a Surface Mount 12 lead
metal power package. It is guaranteed operational from -55°C to +125°C. Available screened to MIL-STD-883, the
VRG8691/92 is ideal for demanding military and space applications.
CURRENT LIMIT (I
CL
)
The VRG8691/92 features internal current limiting making them virtually blowout-proof against overloads. The limit
is nominally 11.5A @ Vin = 5V (see Table 2), but may be increased or decreased with the addition of one external
resistor (see Application Note 2).
1
V
IN
2
3
V
BIAS
ENABLE
GND
4
5
6
VRG8691/92
12
11
10
9
8
7
V
SENSE
Current Limit
Slow Start
V
OUT
FIGURE 1 – BLOCK DIAGRAM / SCHEMATIC
SCD8691 Rev G
ABSOLUTE MAXIMUM RATINGS
PARAMETER
Operating (Junction) Temperature Range
Lead Temperature (soldering, 10 sec)
Storage Temperature Range
V
BIAS
, V
IN
Thermal Resistance (Junction to case
JC
)
Power
RANGE
-55 to +150
300
-65 to +150
7
1
25 1/
UNITS
°C
°C
°C
V
°C/W
W
1/ Based on pass transistor limitations of (V
IN
- V
O
) x I
O
and
JC
< 1°C/W with 25°C max T
J
rise and T
C
= +125°C.
NOTICE: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings
only; functional operation beyond the “Operation Conditions” is not recommended and extended exposure beyond the “Operation
Conditions” may effect device reliability.
RECOMMENDED OPERATING CONDITIONS
PARAMETER
Output Voltage Range
Case Operating Temperature Range
Output Current
V
BIAS
V
IN
1/ V
BIAS
must maintain a level equal or above V
IN
but not fall below 3.3V
2/ Depending upon V
OUT
setting.
RANGE
1.0 to 3.3
-55 to +125
0 to 7.5
3.3 to 5.5 1/
1.8 to 5.5 2/
UNITS
V
DC
°C
A
V
DC
V
DC
ELECTRICAL PERFORMANCE CHARACTERISTICS 1/
PARAMETER
Reference Voltage
Line Regulation
Load Regulation
SYM
V
REF
CONDITIONS
V
IN
= V
BIAS
= 5V,
ENABLE
= 0, 0A < I
OUT
< 7.5A
2V < V
IN
< 3V, V
OUT
= 1.0V, C
IN
> 47µF,
4.3V < V
IN
< 5.3V, V
OUT
= 3.3V, C
OUT
> 47µF,
0A < I
OUT
< 7.5A, C
IN
> 47µF, C
OUT
> 47µF,
f = 120Hz, C
LOAD
= 47µF,
V
IN
+ V
RIP
> V
OUT
+ V
DROP
(
MAX
) @ 5A,
V
IN
= 4.3V, V
RIP
= 1V
P
-
P
, V
OUT
= 3.3V
V
DROP
I
ADJ
I
MIN
I
CL
@V
OUT
= 1%, 0A < I
OUT
< 7.5A
MIN
0.985
-
-
MAX
1.015
0.2
0.5
UNITS
V
%/V
%
V
OUT
V
IN
V
OUT
I
OUT
Ripple Rejection Ratio
Dropout Voltage
Adjustment Pin Current
Minimum Load Current
Current Limit 2/
Long Term Stability 3/
Supply Current (V
BIAS
)
80
-
-
-
9.5
-
-
-
0.5
3
0
13.5
1
15
dB
V
µA
mA
A
%
mA
V
OUT
T
IME
I
BIAS
Notes:
1/ Unless otherwise specified, these specifications apply for post radiation: V
BIAS
= V
IN
= 5V, V
OUT
= 3.3V, I
OUT
= 7.5A and -55°C < Tc <+125°C, Min
Input/Output capacity of 47µF Tant with 1µF ceramic in parallel.
2/ Current Limit is adjustable as shown in Application Note 2, Figures 3 and 4.
3/ Not tested. Shall be guaranteed to the specified limits after 1000hr life test.
SCD8691 Rev G 6/4/13
2
Aeroflex Plainview
APPLICATION NOTE 1
BASIC SET-UP
Setting the output voltage (V
OUT
):
V
BIAS
0.1µF
4
V
BIAS
V
IN
1µF
CER
+ 47µF
TANT
1
2
3
8
5
VRG8691/92
10
V
IN
V
OUT
V
OUT
11
12
C
URR
.
L
IMIT
E
NABLE
1/
C
URR
.
L
IMIT
E
NABLE
S
LOW
S
TART
V
SENSE
9
7
0.1µF
1µF
+
R1
CER
C
LOAD
47µF
TANT
G
ND
6
I
ADJ
V
REF
(=1
V
)
To set the output voltage for a particular Vout:
- Choose an R2 value. (Recommended value = 1
k
- Then use the following formula to determine the value of R1.
R2
R1 = R2 x
V
OUT
- V
REF
(R2 x I
ADJ
) + V
REF
, where V
REF
= 1v, I
ADJ
typ = 0.2uA
Table 1 shows example values for R1 and R2 to achieve some standard voltages.
Table 2 shows the nominal current limit settings if the ’C
URR
. L
IMIT
’ function (pin 8) is left open.
Table 1
Example R1 & R2 for typical V
OUT
V
OUT
3.3V
2.5V
1.8V
1.0V
R2
1k
1k
1k
1k
R1
2.3k
1.5k
800
0
V
IN
5V
3.3V
2.5V
1.8V
Table 2
2/
I
CL NOM
11.5A
7.5A
5.7A
4.1A
Notes:
1/ ENABLE should be asserted after both V
IN
and V
BIAS
are applied.
(See Application Note 3, Figure 5 for the configuration where a separate ENABLE control line is NOT required).
2/ I
CL
varies directly with V
IN
.
(See Application Note 2 for adjusting the Current Limit, I
CL
).
FIGURE 2 –SETTING OUTPUT VOLTAGE
SCD8691 Rev G 6/4/13
3
Aeroflex Plainview
APPLICATION NOTE 2
SETTING THE CURRENT LIMIT
To Increase the Current Limit (I
CL
):
V
BIAS
0.1µF
4
V
BIAS
V
IN
1µF
CER
+ 47µF
TANT
1
2
3
5
8
VRG8691/92
10
V
IN
V
OUT
11
12
V
OUT
E
NABLE
E
NABLE
S
LOW
S
TART
V
SENSE
9
7
0.1µF
1µF
+
R1
CER
C
LOAD
47µF
TANT
C
URR
.
L
IMIT
G
ND
6
R
INC
I
ADJ
V
REF
(=1
V
)
R2
- If the ’C
URR
. L
IMIT
’ function (pin 8) is left open, the I
CL
decreases from 11.5 A(
NOM
) as V
IN
is decreased from 5V (Table 3).
Table 3
V
IN
5V
3.3V
2.5V
1.8V
R
INC
Open
Open
Open
Open
I
CL NOM
11.5 A
7.5 A
5.7 A
4.1 A
- To increase the current limit above the nominal setting for any V
IN
and I
CL
combination, use the following formula:
R
INC
(
K
-
OHMS
) =
(
30 x V
IN
30 x I
CL
- V
IN
69
)
- To maintain I
CL
at the 11.5 A setting, for commonly found V
IN
voltages, apply R
INC
value found in Table 4.
Table 4
V
IN
5V
3.3V
2.5V
1.8V
R
INC
Open
56k
30k
16k
I
CL NOM
11.5 A
11.5 A
11.5 A
11.5 A
FIGURE 3 – INCREASING THE CURRENT LIMIT (I
CL
)
SCD8691 Rev G 6/4/13
4
Aeroflex Plainview
APPLICATION NOTE 2 (
CONTINUED
)
SETTING THE CURRENT LIMIT
To Decrease the Current Limit (I
CL
):
V
BIAS
0.1µF
4
V
BIAS
V
IN
R
DEC
1µF + 47µF
CER
TANT
1
2
3
8
5
VRG8691/92
10
V
OUT
V
IN
V
OUT
11
12
C
URR
.
L
IMIT
E
NABLE
C
URR
.
L
IMIT
E
NABLE
S
LOW
S
TART
V
SENSE
9
7
0.1µF
1µF
+
R1
CER
C
LOAD
47µF
TANT
G
ND
6
I
ADJ
V
REF
(=1
V
)
R2
- As shown in Table 3, if the ’C
URR
. L
IMIT
’ function (pin 8) is left open, the I
CL
decreases from 11.5 A(
NOM
) as V
IN
is
decreased from 5V.
- To achieve any I
CL
, less than nominal, use R
DEC
which can be calculated using the following formula:
R
DEC
(
K
-
OHMS
) =
(
31 x V
IN
69 x V
IN
- I
CL
30
)
FIGURE 4 – DECREASING THE CURRENT LIMIT (I
CL
)
SCD8691 Rev G 6/4/13
5
Aeroflex Plainview
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