JPS6260181A - Multi-output power supply system - Google Patents

Abstract

PURPOSE:To improve the degree of voltage freedom by providing optionally a strap terminal to each output circuit of a multi-output switching power supply containing a voltage inverter and connecting those output circuits in series or in parallel by the straps or separating the output circuits from each other. CONSTITUTION:A multi-output power supply system consisting of a voltage inverter delivers three different levels of outputs +5V, +12V and +12V respectively. Then two pieces of +12V outputs are connected in series when an 8-inch magnetic disk or the 8-inch and 5-inch disks are driven. Thus a power supply unit is obtained for drive three channels of +5V, +12V and +24V. When only the 5-inch disk is driven, two sets of +12V outputs are used with a common ground to secure a power supply unit for two channels of +5V and +12V. Thus the degree of voltage freedom is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a multi-output power supply system, and particularly to a multi-output power supply system suitable for driving a small magnetic disk.

[Background of the invention]

For flexible disks and hard disks, 24
From vjl dynamic 8-inch magnetic file, 12V will be used in the future.
[There is a shift towards dynamic 5-inch or 3.5-inch magnetic files, and it is thought that a power supply that can handle both will be required for the time being. As described in Japanese Utility Model Application Publication No. 51-148219, in a conventional multi-output switching power supply, the necessary DC output for one primary circuit is limited to output 1. Output 2. They are prepared independently from output 3, etc. That is, the input winding of the transformer and the DC circuit of the switching element are connected to a DC power source, and a smoothing circuit consisting of a diode, a choke coil, and a capacitor is connected to each of the plurality of output windings of this transformer, and outputs 1. Output 2.
In addition, the output capacity of this power supply is limited by the components of the secondary circuit, and for example, in order to reduce the output power of output 1 and increase the output power of output 2. Therefore, it is necessary to increase the rating of each secondary circuit component. That is, each output circuit consists of a diode, a choke coil, and a capacitor.
To supply a current of A.

Each part is connected for a rating of 5A, but if necessary,
If it is desired to supply the output of the OA, since each is independent, there is no flexibility, and parts rated for 10A must be connected to each.

[Purpose of the invention]

The purpose of the present invention is to improve the conventional problems and provide a multi-output power supply that increases the degree of freedom for voltage channels and allows a more flexible computer system to be configured in the adoption of a compact and low-cost magnetic disk unit. The goal is to provide a system.

[Summary of the invention]

In order to achieve the above object, the multi-output power supply system of the present invention is a switching power supply comprising one voltage conversion inverter and having a plurality of output circuits, in which devices with different drive voltages are supplied from a common power supply. The present invention is characterized in that each output circuit is provided with a strap terminal arbitrarily, and each output circuit is connected in series, connected in parallel, or separated by the strap to supply different output voltages.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described in detail with reference to one drawing.

FIG. 1 is a configuration diagram of a power supply system for a magnetic disk drive showing one embodiment of the present invention.

The circuit shown in Figure 1 is a general multi-output switching power supply, and the output voltages are +5V and +12V.

It has 3 channels of +12v. 10 is a primary capacitor, 11 is a transistor switching element, 13 is a main transformer, 14 is a diode, 15 is a choke coil,
16 is a capacitor. Up to this point, there is no difference from the conventional method, but the present embodiment is new in that the output terminals of ■-〇 and output terminals of ■-■ are selectively strapped, respectively.

In other words, in this embodiment, the output voltage configuration of the multi-output power supply system is set to 3 outputs of +5V, +12V, and +12V, and the output voltage configuration of the multi-output power supply system is set to three outputs of +5V, +12V, and +12V.
In case of mixed drive of inch type and 5 inch type, two +1
By connecting 2V in series, +5V, +12V, +
Operates as a 24V 3-channel power supply unit, with 5
When driving only inch-based magnetic disk drives, 2
By using the +12V of the pair as a common ground,
It operates as a 2-channel power supply unit of +5V and +12V. This allows you to use 8-inch flexible disk drives and hard disk drives that require +5V and +24V, as well as 5-inch flexible disk drives and hard disk drives that require +5V and +12V, at the same time, or only one of them, without waste. It can be driven by

FIG. 2 is a diagram of a magnetic disk storage box used, and FIG. 3 is a diagram showing the strap and output terminal in FIG. 1 and their voltages.

The power supply system shown in FIG. 1 is provided to drive a magnetic disk device. As shown in Fig. 2, magnetic disk devices used for files in personal computers and office computers include an 8-inch flexible disk, 2.5-inch flexible disk, 3.8-inch hard disk 4,
There are also 5-inch hard disks 5, etc. 8 above
Inch and 5 inches are names for the diameter of a magnetic disk. The driving voltage for the 8-inch system is +5V.
, and +24V, 5 inch system to +5V, +12V,
Each is unified.

In a personal computer or an office computer, it is desirable that the degree of freedom in connecting magnetic disk devices be as large as possible because it is essential to effectively utilize user software assets. In other words, there is a combination of an 8-inch flexible disk for the use of user software and a 5-inch hard disk for miniaturization, or a combination of a 5-inch flexible disk and a 5-inch hard disk for miniaturization when building a new system. It is desirable to have a system that allows various other combinations.

However, the difference in driving voltage between the 8-inch system and the 5-inch system limits the above-mentioned degree of freedom. Therefore, in this embodiment, +5V and +12V as shown in FIG.
, +12V three-channel power supplies are combined according to the connection conditions in the table shown in FIG. 3 to configure a lean power supply unit. As shown in the table of FIG. 3, the output terminal to be used and its voltage are determined by changing the strap depending on the disk device to be connected. The combination of connection conditions is +5V, +1
2V, +24V (7) and +5V.

By configuring three types: +24V, +5V, and +12V, a lean source unit is realized for a combination of disk devices. First, if both 5-inch and 8-inch disk devices are connected, by applying strap A, terminals ■ and ■ will be connected, and the output voltage will be doubled by connecting the two output circuits in series. 24 of
It becomes V.

That is, +5V is supplied from the top output circuit, +24V is supplied from the terminal ■ of the next output circuit, and +12V is supplied from the terminal ■ of the bottom output circuit.

Ov is output from the terminal ■. Next, if only a 5-inch disk device is connected, by applying strap B, the output terminals ■ and ■ will be connected and the ground voltage will be common, so the two channels will be connected in parallel. , and the output voltage remains unchanged at +12V,
The output capacity (current value) is doubled. In other words, if 5A is supplied in the case of a single-output circuit, IOA will be supplied. Furthermore, the number of connected disk devices is 8.
In the case of only an inch, by applying strap A, output terminals ■ and ■ are connected, two channels are connected in series, and a double voltage of +24V is supplied from the terminal. OV is supplied to the terminal (2).

FIG. 4 is a configuration diagram of a multi-output power supply system showing another embodiment of the present invention.

FIG. 4 shows a configuration example of an overcurrent protection circuit in a power supply system when the multi-output switching power supply system of FIG. 1 is used in combination by changing connections. In Figure 4, 18.19 is a resistor for detecting overcurrent, and 21
．． 22 is a comparator for comparing the reference voltage VREF and the detection voltage, 23 is a comparator, and the PWN circuit (
(pulse width modulation circuit), 12 is a drive transformer.

Other symbols are the same as those in FIG. In order to connect one of the two +12v output circuits in series to obtain +24v, that circuit must be set to a floating voltage. In order to protect the power supply system from load short circuits, etc., the power supply system is equipped with an overcurrent protection circuit. This circuit generally converts the current flowing through the circuit into a voltage using a resistor or the like, and detects the level using a comparator.

When one circuit is used for bloating as in the circuit of this embodiment, the detection section using the comparator must also be compatible with bloating.

It is extremely difficult. A convenient method is to use a current transformer to pick up the pulsating current before the rectifier diode 14, but this requires high-strength winding components and a rectifier circuit.

Therefore, in this embodiment, straps A and B are applied to the output terminals of this overcurrent detection circuit as well, so that overcurrent can be detected effectively.

Note that the output terminal number ■ in FIG. 4 corresponds to the terminal in FIG. 1, and the terminals ■ and ■ also correspond to the terminals ■ and ■ in FIG. Also, the terminal ■ in Figure 4 is the terminal ■ in Figure 1,
Terminal ■' in FIG. 4 has no equivalent terminal in FIG.

The output potential difference v2, which should be a floating output, is 12V.
The fixed potential v1 is also +12V.

Here, current detection resistors (RcLt) 18 and 7 of the v1 circuit
Two circuits of current detection resistors (RCL2) 19 are provided.

The current flowing through these detection resistors 18 and 19 becomes an overcurrent when a short circuit or the like occurs in the load. Since the potential of the output terminals ■' and ■ is oV, the larger the current, the higher the detection resistance 18.1
The voltage between terminals 9 becomes large on the negative side. These detected voltages are determined by comparators 21 and 22, respectively, to a comparison reference voltage VREF.
When it becomes lower than this reference voltage, it is OR-connected as a low voltage input to the comparator 23.

A sawtooth wave is input to one input of this comparator 23, and the pulse width of this wave is controlled by the other input.

The output of the comparator 23 is.

The switching transistor 11 is driven via the drive transformer 12. In other words, the larger the detection voltage is on the negative side compared to the reference voltage, the shorter the pulse width is controlled, so the time width in which switching of the switching element 11 is controlled becomes shorter, and accordingly, the output voltage of the DC output circuit decreases. decreases. This reduces the damage caused by the load. That is, in the circuit of this embodiment, when the current of either one of the floating voltages V 1 + V 2 exceeds a prescribed value, the pulse width decreases and exhibits a so-called drooping characteristic.

With the circuit shown in Figure 4, either current is generated when connected in parallel (strap B), and v1 when connected in series (strap A).
Each circuit current (including the V2 circuit current) is detected. When connected in series, the current detection resistor 19 of the 72 circuit is in an oven state, but the input voltage of the comparator 21 is 12
V, and there is no inversion of the output of the comparator 21. Note that the straps A and B in FIG. 4 have the same function as the straps A and B in FIG.

By configuring such an overcurrent protection circuit, it is possible to connect various magnetic disk drives without impairing the overcurrent protection function by simply changing the external connections without changing the internal connections of the power supply system. It is possible to supply power. Although this embodiment has been described as a power supply system for a magnetic disk device, the system of the present invention can also be applied to the case of supplying power to a computer processing device or other input/output equipment.

〔Effect of the invention〕

As explained above, according to the present invention, by arbitrarily strapping the output terminals of a plurality of output circuits, different voltages can be supplied to each of them. It becomes possible to employ small and low-cost equipment, and it is possible to configure a flexible computer system by increasing the degree of freedom regarding voltage channels.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a multi-output power supply system showing an embodiment of the present invention, FIG. 2 is a diagram showing the types of magnetic disk drives to which power is supplied by the system of FIG. 1, and FIG. FIG. 4 is a diagram illustrating the strapping method shown in FIG. 4, and FIG. 4 is a configuration diagram of an overcurrent protection circuit in a multi-output power supply system showing another embodiment of the present invention. 10: Primary capacitor, 11 Ni switching transistor, 12 Ni drive transformer, 13: Main transformer,
14: Diode, 15: Choke coil, 16: Secondary capacitor, 18, 19: Current detection resistor, 21, 22,
23: Comparator, VREF: Reference DC voltage. Patent applicant: Hitachi, Ltd. (No. 1 is one person) Representative a
4. □Masatoshi Isomura, '[゛:,-;7j Figure 1 Figure 2

Claims (1)

[Claims] (1) In a switching power supply consisting of one voltage conversion inverter and equipped with multiple output circuits, in order to supply devices with different drive voltages from a common power supply, each output circuit is provided with an optional strap terminal, A multi-output power supply system characterized in that each output circuit is connected in series, connected in parallel, or separated by the strap to supply different output voltages.