JPH0214294Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention comprises a switching element SCR connected in series to a battery 1 to control charging of the battery 1, and a charging control section 3 controlling the switching element SCR based on the output voltage of a reference voltage generation circuit 2. and a hysteresis circuit 4 connected between a transistor Tr ₂ that is turned on when the battery 1 is not being charged and the reference voltage generating circuit 2 and reducing the output voltage of the reference voltage generating circuit 2 when the battery 1 is not being charged. , the transistor when adjusting the output voltage of the reference voltage generation circuit 2.
A charger in which an adjustment piece 6 having a short-circuit pattern 12 formed so that Tr ₂ is turned off is integrally provided on a printed wiring board 5, and the adjustment piece 6 is removed after adjustment is completed. It is.

The purpose of this invention is to easily and accurately set the reference voltage of a charger with a large hysteresis width, that is, the difference between the voltage at which battery charging is stopped and the voltage at which battery charging is resumed. be.

Generally, when performing charging control by comparing the set reference voltage and battery voltage, in order to keep the charging current during charging control to a low level where there is no risk of overcharging, it is necessary to set the voltage at which charging stops and when charging again. What is necessary is to increase the difference between the voltage and the so-called hysteresis width. In FIG. 1, when the battery voltage reaches the charging cut-off voltage (voltage at which charging is stopped), a part of the reference current flowing to the reference voltage generating circuit is shunted to provide the above-mentioned hysteresis. The details of FIG. 1 will be explained below.

In Figure 1, 1 is a battery, and switching elements SCR are connected in series.
compares the output from the charging control section 3 with the voltage of the battery 1 and performs a switching operation to control charging of the battery 1. 2 is a reference voltage generation circuit, and charging control section 3
Charging control IC 9 consisting of transistors Tr ₁ to Tr ₃
connected to the terminal. The terminal serves as a constant current source for the reference voltage generation circuit 2, and at the same time detects the voltage across the reference voltage generation circuit 2. The reference voltage generating circuit 2 includes a diode D ₄ which is placed in close contact with the battery 1.
It has a series circuit of _D5 , and is configured to detect a temperature change of the battery 1 as a change in the forward voltage drop of the diodes _D4 and _D5 . In this way, in the reference voltage generation circuit 2, the diodes D ₄ and D ₅ and the resistor R ₅ ,
Reference voltage as the voltage across the series circuit with R ₇ and Rv
Generate V _REF . Here, since the reference current I _S (230 μA) from the terminal is supplied to the reference voltage generating circuit 2, the reference voltage V _REF can be directly changed in accordance with the temperature change of the battery 1. The terminal is connected to the connection point of resistors R ₃ and R ₄ that determine the amplification rate of the input voltage to the terminal, and when the reference voltage V _REF is input to the terminal, the output voltage from the terminal is (1 + R ₃ /R ₄ ) becomes V _REF . The terminal is connected to the negative pole of the power supply. Tr ₂ is a transistor that is turned on when the battery 1 is not being charged.When the charging current is flowing through the battery 1, the output voltage of the rectifier circuit 7 decreases, but when it is not being charged, it increases, so this voltage change is handled by the charging control section. 3, transistor Tr ₃ is turned on, and transistors Tr ₁ and Tr ₂ are turned on. 4
is a hysteresis circuit, which is connected between the reference voltage generation circuit 2 and the terminal connected to the transistor Tr ₂ , and when not charging, in other words, when the transistor Tr ₂ is on, a part of the reference current of the reference voltage generation circuit 2 is generated. (for example, 10μA) and connect it to transistor Tr ₂
This is to lower the reference voltage. Reference numeral 8 denotes a display element for displaying charging, which is connected to a terminal, lights up during charging, and turns off when charging is completed by turning on transistor Tr ₂ . still,
In addition to the above-mentioned terminals, there are provided a terminal for power supply connection, a terminal connected to the base of transistor _Tr1 , and a terminal connected to capacitor C.

In the above-mentioned charger, the voltage of the battery 1 is determined by the charging control IC 9 based on the output voltage of the reference voltage generation circuit 2.
The switching element SCR is controlled by the output of the terminal to control charging, and when the voltage of the battery 1 reaches a predetermined voltage, that is, the charging cut voltage, the switching element SCR is turned off. As a result, the transistor Tr ₂
is turned on, the reference current is shunted through the hysteresis circuit 4, the output voltage of the reference voltage generation circuit 2 is reduced, and the output voltage of the terminal of the charging control IC 9 is also reduced, so that the charging cut voltage is reduced immediately after charging is cut off. As a result, hysteresis characteristics can be obtained, overcharging can be prevented, and battery deterioration can be prevented.

When adjusting the charging cut-off voltage having such hysteresis characteristics using the variable resistor R _V of the reference voltage generation circuit 2, in other words, when setting the reference voltage to obtain a predetermined charging cut-off voltage, the conventional method is as shown in Fig. 2. In addition, since the voltage Vth ₂ immediately before the charging cut and the voltage Vth ₁ immediately after the charging cut are detected, there is a difference between detecting and reading while increasing the battery voltage and detecting and reading while decreasing the battery voltage, and when the hysteresis width is wide. However, it was difficult to set the reference voltage accurately.

The present invention has been devised in view of this point, and will be described in detail below with reference to Examples.

In Fig. 3, 5 is a printed wiring board;
The circuit shown in the figure is soldered to form the circuit shown in FIG. 1. Reference numeral 6 is an adjustment piece, which is broken at line A--A and removed when it is assembled into a product after adjustment. 10 is a pattern connected to the terminal in FIG. 1, and 11 is a pattern connected to the terminal. Both patterns 10 and 11 are connected by a shorting pattern 12 provided on the adjustment piece 6.

Now, when the circuit components are soldered to the printed wiring board 5 and the charging cutoff voltage is adjusted, the adjustment piece 6
Since the terminals are short-circuited by the short-circuiting pattern 12, the terminals are at ground potential, and the transistors Tr ₁ and Tr ₂ are always in an off state. Therefore, even if the charging cut-off state occurs while the charging cut-off voltage is being adjusted, the hysteresis circuit 4 does not operate, and the charging cut-off voltage can be easily adjusted. By removing the adjusting piece 6 after the adjustment is completed, the transistors Tr ₁ and Tr ₂ operate normally, and the hysteresis circuit 4 comes to operate.

As described above, in the present invention, an adjustment piece having a short-circuit pattern formed so that the transistor is turned off when adjusting the output voltage of the reference voltage generation circuit is integrally provided on the printed wiring board, and after the adjustment is completed, the adjustment piece is Since the pieces are removed, the reference voltage can be easily set and adjusted with high accuracy even if the difference between the voltage at which charging of the battery is stopped and the voltage at which it is charged again is increased.

[Brief explanation of drawings]

Fig. 1 is a basic circuit diagram of a charger, Fig. 2 is a characteristic diagram of a conventional charger during reference voltage adjustment, and Fig. 3 is a partially cutaway front view of a printed wiring board according to an embodiment of the present invention. be. 1...Battery, 2...Reference voltage generation circuit, 3...
Charging control section, 4...Hysteresis circuit, 5...Printed wiring board, 6...Adjustment piece, 12...Short circuit pattern, SCR...Switching element, Tr ₂ ...Transistor.

Claims (1)

[Scope of utility model registration request] a switching element connected in series with a battery to control charging of the battery; a charging control section controlling the switching element based on the output voltage of a reference voltage generation circuit; a transistor that is turned on when the battery is not being charged; and the reference voltage generation circuit. In a charger equipped with a hysteresis circuit that is connected between the hysteresis circuit and the hysteresis circuit that lowers the output voltage of the reference voltage generation circuit when not charging, the short circuit pattern is formed so that the transistor is turned off when the output voltage of the reference voltage generation circuit is adjusted. A charger comprising an adjustment piece having an adjustment piece integrally protruding from a printed wiring board, and the adjustment piece being removed after adjustment is completed.