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BM1084 GENERAL DESCRIPTION
The BM1084 series of adjustable and fixed voltage regulators are designed to provide 5A output current and to operate down to 1V input-to-output differential. The dropout voltage of the device is guaranteed maximum 1.5V at maximum output current, decreasing at lower load currents. On-chip trimming adjusts the reference voltage to 1%. Current limit is also trimmed, minimizing the stress under overload conditions on both the regulator and power source circuitry. The BM1084 devices are pin compatible with older three-terminal regulators and are offered in 3 lead TO-220-2 lead TO-252 package and 3 and 2 lead TO-263 (Plastic DD).
FEATURES
Three Terminal Adjustable or Fixed Voltages* 5V, 1.8V, 2.5V, 2.85V, 3.3V and 5.0V Output Current of 5A Operates Down to 1V Dropout Line Regulation: 0.2% Max. Load Regulation: 0.4% Max. TO-220 ,TO252and TO-263 package available
APPLICATIONS
High Efficiency Linear Regulators Post Regulators for Switching Supplies Microprocessor Supply Constant Current Regulators Battery Chargers Notebook/Personal Computer Supplies Portable Instrumentation
ORDERING INFORMATION
PACKAGE TYPE 3 LEAD TO-220 BM1084 BM1084-1.5 BM1084-2.5 BM1084-2.85 BM1084-3.0 BM1084-3.3 BM1084-3.5 BM1084-5.0 TO-252 BM1084 BM1084-1.5 BM1084-2.5 BM1084-2.85 BM1084-3.0 BM1084-3.3 BM1084-3.5 BM1084-5.0 2&3 LEAD TO-263 BM1084 BM1084-1.5 BM1084-2.5 BM1084-2.85 BM1084-3.0 BM1084-3.3 BM1084-3.5 BM1084-5.0 OPERATING JUNCTION TEMPERATURE RANGE 0 to 125C 0 to 125C 0 to 125C 0 to 125C 0 to 125C 0 to 125C 0 to 125C 0 to 125C
PIN DESCRIPTIONS
FIXED VERSION 1- Ground 2- VOUT 3- VIN ADJUSTABLE VERSION 1- Adjust 2- VOUT 3- VIN
BOOKLY MICRO ELECTRONIC LIMITED CORP.
SPECIFICATION
BM1084
ABSOLUT MAXIMUM RATINGS(Note 1)
Power Dissipation Input Voltage Operating Junction Temperature Control Section Power Transistor Storage temperature 0C to 125C 0C to 150C - 65C to +150C Internally limited 22V Soldering information Lead Temperature (10 sec) Thermal Resistance TO-220 package TO-263 package JA= 50C/W JA= 30C/W* 300C
* With package soldering to copper area over backside ground plane or internal power plane JA can vary from 20C/W to >40C/W depending on mounting technique and the size of the copper area.
ELECTRICAL CHARACTERISTICS
Electrical Characteristics at IOUT = 0 mA, and TJ = +25C unless otherwise specified.
Parameter
Reference Voltage (Note 2)
Device
BM1084
Conditions
IOUT = 10 mA 10mA IOUT 5A, 1.5V (VIN - VOUT) 12V
Min
1.238 1.225
Type
1.250 1.250
Max
1.262 1.270
Units
V V
Output Voltage (Note 2)
BM1084-1.5
1.485
1.500 1.500 2.500 2.500 2.850 2.850 3.000 3.000 3.300 3.300 3.500 3.500 5.000 5.000
1.515 1.530 2.525 2.550 2.88 2.91 3.300 3.360 3.333 3.365 3.535 3.570 5.050 5.100
V V V V V V V V V V V V V V
0IOUT 5A ,3.0VVIN 12V 0IOUT 5A ,4.0VVIN 12V 0IOUT 5A ,4.35VVIN 12V 0IOUT 5A ,4.5VVIN 12V 0IOUT 5A ,4.75VVIN 12V 0IOUT 5A ,5.0VVIN 12V 0IOUT 5A ,6.5VVIN 12V
1.470 2.475 2.450 2.82 2.79 2.970 2.940 3.267 3.235 3.465 3.430 4.950 4.900
BM1084-2.5
BM1084-2.85
BM1084-3.0
BM1084-3.3
BM1084-3.5
BM1084-5.0
BOOKLY MICRO ELECTRONIC LIMITED CORP.
SPECIFICATION
Parameter
Line Regulation
BM1084
Device Conditions
ILOAD = 10 mA ,
Min
Typ
0.3 0.6 0.1 0.2 3 6 3 6 3 6 3 6 3 7 3 6 5 10 1.3
Max
6 10 0.3 0.4 12 20 12 20 12 20 12 20 15 25 15 25 20 35 1.5
Units
mV mV % % mV mV mV mV mV mV mV mV mV mV mV mV mV mV V
BM1084/-1.5/-2.5/-2.85/ -3.0/-3.3/-3.5/-5.0
1.5V(VIN - Vout ) 12V (VIN - Vout ) =3V, 10mAIOUT 5A
VIN = 5V, 0IOUT 5A VIN = 5V, 0IOUT 5A VIN = 5V, 0IOUT 5A VIN = 5V, 0IOUT 5A VIN = 5V, 0IOUT 5A VIN = 5.25V, 0IOUT 5A VIN = 8V, 0IOUT 5A VOUT , VREF = 1%, IOUT = 5 A (Note 4) (VIN - VOUT) = 5V (VIN - VOUT) = 12V (Note 5) 5.00
Load Regulation (Notes 2, 3)
BM1084-ADJ
BM1084-1.5
BM1084-2.5
BM1084-2.85
BM1084-3.0
BM1084-3.3
BM1084-3.5
BM1084-5.0
Dropout Voltage (VIN - VOUT) Current Limit
BM1084/-1.5/-2.5/-2.85/ -3.0/-3.3/-3.5/-5.0 BM1084/-1.5/-2.5/-2.85/ -3.0/-3.3/-3.5/-5.0
6.00
7.00
A
Minimum Load Current Quiescent Current
BM1084
5
10
mA
BM1084/-1.5/-2.5/-2.85/ -3.0/-3.3/-3.5/-5.0
VIN 12V f =120Hz , COUT = 25F Tantalum, IOUT = 5A,(VIN-VOUT ) = 3V, CADJ =25F 60
5
10
mA
Ripple Rejection
BM1084
75
dB
BM1084-1.5
f =120Hz , COUT = 25F Tantalum, IOUT = 5A, VIN = 4.5V
60
72
dB
BM1084-2.5
f =120Hz , COUT = 25F Tantalum, IOUT = 5A, VIN = 5.5V
60
72
dB
BM1084-2.85
f =120Hz , COUT = 25F Tantalum, IOUT = 5A, VIN = 6V
60
72
dB
BM1084-3.0
f =120Hz , COUT = 25F Tantalum, IOUT = 5A VIN = 6V
60
72
dB
BM1084-3.3
f =120Hz , COUT = 25F Tantalum, IOUT = 5A VIN = 6.3V
60
72
dB
BM1084-3.5
f =120Hz , COUT = 25F Tantalum, IOUT = 5A VIN = 6.5V
60
72
dB
BM1084-5.0
f =120Hz , COUT = 25F Tantalum, IOUT = 5A, VIN = 8V
60
68
dB
BOOKLY MICRO ELECTRONIC LIMITED CORP.
SPECIFICATION
Parameter
Thermal Regulation Adjust Pin Current
BM1084
Conditions
TA = 25C, 30ms pulse 10mA IOUT 5A , 1.5V(VIN - VOUT) 12V
Device
BM1084 BM1084
Min
Typ
0.008 55
Max
0.04
Units
%W A
120 0.2 5.0
A A
Adjust Pin Current Change Temperature Stability Long Term Stability
BM1084
10mA IOUT 5A , 1.5V(VIN - VOUT) 12V
0.5 TA =125C, 1000Hrs 0.3 1
% %
RMS Output Noise (% of VOUT ) Thermal Resistance Junction-to-Case
TA = 25C , 10Hz f 10kHz M Package: Control Circuitry/ Power Transistor T Package: Control Circuitry/ Power Transistor
0.003
%
1.5/4.0 1.5/4.0
C/W C/W
Parameters identified with boldface type apply over the full operating temperature range.
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. For guaranteed specifications and test
conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed.
Note 2: Line and Load regulation are guaranteed up to the maximum power dissipation of 15W. Power dissipation is determined by the
input/output differential and the output current. Guaranteed maximum power dissipation will not be available over the full input/output range.
Note 3:See thermal regulation specifications for changes in output voltage due to heating effects. Line and load regulation are measured at
a constant junction temperature by low duty cycle pulse testing. Load regulation is measured at the output lead ~1/8" from the package.
Note 4: Dropout voltage is specified over the full output current range of the device. Note 5: Minimum load current is defined as the minimum output current required to maintain regulation. When (VIN - VOUT) = 12V the device
is guaranteed to regulate if the output current is greater than 10mA.
APPLICATION HINTS
The BM1084 series of adjustable and fixed regulators are easy to use and have all the protection features expected in high performance voltage regulators: short circuit protection and thermal shut-down. Pin compatible with older three terminal adjustable regulators, these devices offer the advantage of a lower dropout voltage, more precise reference tolerance and improved reference stability with temperature. Stability The circuit design used in the BM1084 series requires the use of an output capacitor as part of the device frequency compensation. The addition of 150uF aluminum electrolytic or a 22uF solid tantalum on the output will ensure stability for all operating conditions. When the adjustment terminal is bypassed with a capacitor to improve the ripple rejection, the requirement for an output capacitor increases. The value of 22uF tantalum or 150uF aluminum covers all cases of bypassing the adjustment terminal. Without bypassing the adjustment terminal smaller capacitors can be used with equally good results. To ensure good transient response with heavy load current changes capacitor values on the order of 100uF are used in the output of many regulators. To further improve stability and transient response of these devices larger values of output capacitor can be used. Protection Diodes Unlike older regulators, the BM1084 family does not need any protection diodes between the adjustment pin and the output and from the output to the input to prevent over-stressing the die. Internal resistors are limiting the internal current paths on the BM1084 adjustment pin, therefore even with capacitors on the adjustment pin no protection diode is needed to ensure device safety under short-circuit conditions. Diodes between the input and output are not usually
BOOKLY MICRO ELECTRONIC LIMITED CORP.
SPECIFICATION
needed. Microsecond surge currents of 50A to 100A can be handled by the internal diode between the input and output pins of the device. In normal operations it is difficult to get those values of surge currents even with the use of large output capacitances. If high value output capacitors are used, such as 1000uF to 5000uF and the input pin is instantaneously shorted to ground, damage can occur. A diode from output to input is recommended, when a crowbar circuit at the input of the BM1084 is used. Normal power supply cycling or even plugging and unplugging in the system will not generate current large enough to do any damage. The adjustment pin can be driven on a transient basis 25V, with respect to the output without any device degradation. As with any IC regulator, none the protection circuitry will be functional and the internal transistors will break down if the maximum input to output voltage differential is exceeded. Ripple Rejection
BM1084
The ripple rejection values are measured with the adjustment pin bypassed. The impedance of the adjust pin capacitor at the ripple frequency should be less than the value of R1 (normally 100to120) for a proper bypassing and ripple rejection approaching the values shown. The size of the required adjust pin capacitor is a function of the input ripple frequency. If R1=100at 120Hz the adjust pin capacitor should be 25uF. At 10kHz only 0.22uF is needed. The ripple rejection will be a function of output voltage, in circuits without an adjust pin bypass capacitor. The output ripple will increase directly as a ratio of the output voltage to the reference voltage (VOUT / VREF). Output Voltage The BM1084 series develops a 1.25V reference voltage between the output and the adjust terminal. Placing a resistor between these two terminals causes a constant current to flow through R1 and down through R2 to set the overall output voltage. This current is normally the specified minimum load current of 10mA. Because IADJ is very small and constant it represents a small error and it can usually be ignored.
D1
BM1084 IN OUT ADJ
VIN
VOUT R1 COUT
150uF
VIN
IN
BM1084 OUT ADJ
VOUT VREF R1
CADJ
10uF
R2
IADJ
50uA
R2
Overload Recovery When the power is first turned on, as the input voltage rises, the output follows the input, permitting the regulator to start up into heavy loads. During the start-up, as the input voltage is rising, the input-to-output voltage differential remains small, allowing the regulator to supply large output currents. A problem can occur with a heavy output load when the input voltage is high and the output voltage is low, when the removal of an output short will not permit the output voltage to recover. The load line for such a load may intersect two points on the output current curve. In this case, there are two stable output operating points for the regulator. With this double intersection, the power supply may need to be cycled down to zero and brought up again to make the output recover. VOUT = VREF 1+ R2/R1)+IADJR2
Figure 1. Basic Adjustable Regulator Load Regulation
True remote load sensing it is not possible to provide, because the BM1084 is a three terminal device. The resistance of the wire connecting the regulator to the load will limit the load regulation. The data sheet specification for load regulation is measured at the bottom of the package. Negative side sensing is a true Kelvin connection, with the bottom of the output divider returned to the negative side of the load. The best load regulation is obtained when the top of the resistor divider R1 is connected directly to the case not to the load. If R1 were connected to the load, the effective
BOOKLY MICRO ELECTRONIC LIMITED CORP.
SPECIFICATION
resistance between the regulator and the load would be: RP x( R2+R1 )/ R1 RP = Parasitic Line Resistance Connected as shown below,RP is not multiplied by the divider ratio. Using 16-gauge wire the parasitic line resistance is about 0.004per foot, translating to 4mV/ft at 1A load current. It is important to keep the positive lead between regulator and load as short as possible and use large wire or PC board traces.
BM1084
junction-to-case thermal resistance specification, the data section for these new regulators provides a separate thermal resistance and maximum junction temperature for both the Control Section and the Power Transistor. Calculations for both temperatures under certain conditions of ambient temperature and heat sink resistance and to ensure that both thermal limits are met.
Thermal Considerations
The BM1084 series have internal power and thermal limiting circuitry designed to protect the device under overload conditions. However maximum junction temperature ratings
VIN
CX1084
IN OUT ADJ
Rp R1* RL R2*
should not be exceeded under continuous normal load conditions. Careful consideration must be given to all sources of thermal resistance from junction to ambient, including junction-to-case, case-to-heat sink interface and heat sink resistance itself. To ensure safe operating temperatures and reflect more accurately the device temperature, new thermal resistance specifications have been developed. Unlike older regulators with a single junction-to-case thermal resistance specification, the data section for these new regulators provides a separate
Thermal Considerations
The BM1084 series have internal power and thermal limiting circuitry designed to protect the device under overload conditions. However maximum junction temperature ratings should not be exceeded under continuous normal load conditions. Careful consideration must be given to all sources of thermal resistance from junction to ambient, including junction-to-case, case-to-heat sink interface and heat sink resistance itself. To ensure safe operating temperatures and reflect more accurately the device temperature, new thermal resistance specifications have been developed. Unlike older regulators with a single circuitry designed to protect the device under overload
thermal resistance and maximum junction temperature for both the Control Section and the Power Transistor. Calculations for both temperatures under certain conditions of ambient temperature and heat sink resistance and to ensure that both thermal limits are met. Junction-to-case thermal resistance is specified from the IC junction to the bottom of the case directly below the die. This is the lowest resistance path for the heat flow. In order to ensure the best possible thermal flow from this area of the package to the heat sink proper mounting is required. Thermal compound at the case-to-heat sink interface is recommended. A thermally conductive spacer can be used, if the case of the device must be electrically isolated, but its added contribution to thermal resistance has to be considered.
BOOKLY MICRO ELECTRONIC LIMITED CORP.
SPECIFICATION TYPICAL PERFORMANCE CHARACTERISTICS
BM1084
BOOKLY MICRO ELECTRONIC LIMITED CORP.
SPECIFICATION PACKAGE DIMENSIONS inches (millimeters) unless otherwise noted.
3 LEAD TO-220 PLASTIC PACKAGE
BM1084
3 LEAD TO-263 PLASTIC
2 LEAD TO-263 PLASTIC
BOOKLY MICRO ELECTRONIC LIMITED CORP.
SPECIFICATION
TO-252 PLASTIC
BM1084
Note: Bookly Micro corporation assumes no responsibility for any errors which may appear in this document. reserves the right to change devices or specifications detailed herein at any time without notice.
BOOKLY MICRO ELECTRONIC LIMITED CORP.

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