RT9594A 查看數據表（PDF） - Richtek Technology
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RT9594A Datasheet PDF : 10 Pages
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RT9594A/B
Adjustable Input Current
The RT9594A/B simply adjust peak primary current by a
resistor RCS connecting to CS pin as shown in Function
block diagram. RCS determines the peak current of primary
N-MOSFET according to the following Equation :
R CS
=
40000
IPK −PRI
(Ω)
Where the IPK-PRI is the primary peak current. Users could
select appropriate RCS according to the battery capability
and required charging time.
Adjustable Output Voltage
The RT9594A/B sense output voltage by a voltage divider
connecting to the anode of the rectifying diode during OFF
time as shown in Figure 3. This eliminates power loss at
voltage-sensing circuit when charging completed. R1 to
R2 ratio determines the output voltage as shown in the
typical application circuit. The feedback reference voltage
is 1V. If VOUT = 300V, according the following equation :
( ) VOUT
= VFB ×
1 + R1 + R2
R3
, so R1 + R2 = 299.
R3
It is recommend to set R3 = 1kΩ and R1 = R2 = 150kΩ
for reducing parasitic capacitance coupling effect of the
FB pin. R1 and R2 MUST be greater than 0805 size
resistor for enduring secondary HV. Another sensing
method is to sense the output voltage directly as shown
in Figure 4.
VOUT
R1
150k
R2
150k
FB
R3
1k
COUT
Figure 3. Sensing Anode of Diode
VOUT
R1
10M
R2
10M
COUT
FB
C1
10nF
R3
66.5k
Figure 4. Sensing Output Voltage
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8
Lower Charging Current at Low Battery Voltage
The RT9594A/B also offers two stage charging function.
If the resistor divider is connected from VBAT to FBVD to
GND as shown in Figure 5, it will detect the battery voltage.
Because of the reference voltage of the internal detector
is 1V, thus the battery trip point is 2.5V. When battery
voltage is >2.5V, the VDOUT open drain MOS inside the
RT9594A/B will be turned on (VDOUT state become GND),
the peak current value will be determined by R4. When
battery voltage is <2.5V, the VDOUT open drain MOS
inside the RT9594A/B will be turned off (VDOUT state
become OPEN), then the peak current is determined by
R4 series with R5. Thus charging current is decreasing
as shown in Figure 7.
As shown in the Figure 6 circuit, the FBVD voltage also
could be set by the GPIO signal. When GPIO voltage is
>1V, the first stage peak current value will be determined
by R4. When the GPIO voltage is <1V, the second stage
peak current is determined by R4 series with R5.
VBAT
R6
1.5M
R7
1M
1:N
47uF
R5
3k
3.3V
100K
R4
24k
1uF
FBVD
VDOUT
DRVIN
CS
VDRV
RT9594A/B
VDD
DRVOUT
STAT
CHARGE
AGND
GSD2004S
R1
150k
R2
150k
VOUT
COUT
100uF
/330V
R3
1k
Strobe
3.3V/5V
0.1uF
To IGBT Gate
Figure 5. Two Stage Charging Application Circuit
VBAT
1:N
47uF
GPIO
R5
3k
3.3V
100K
R4
24k
1uF
FBVD
VDOUT
DRVIN
CS
VDRV
RT9594A/B
VDD
DRVOUT
STAT
CHARGE
AGND
GSD2004S
R1
150k
R2
150k
VOUT
COUT
100uF
/330V
R3
1k
Strobe
3.3V/5V
0.1uF
To IGBT Gate
Figure 6. Two Stage Charging by GPIO Signal
DS9594A/B-02 April 2011
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