Richtek RT9903BPQV Schematic [ru]
Preliminary
RT9903B
4 Channel DC/DC Converters IC
with High-Efficiency Step-up
General Description
The RT9903B is a complete power-supply solution for
digital still cameras and other hand-held devices. It
integrates a high-efficiency fours step-up DC-DC
converte
rs and a charge pump.
The two Step-up DC-DC converters (CH1,CH2) accept
inputs from 1.5V to 5.5V and regulate a resistor-
adjustable output up to 17V. One Step-up DC-DC
converter (CH3) can be regarded as white LED Driver,
which reference voltage is 0.2V and have OVP function.
One step-up DC-DC converter (CH4) regulate a resistor-
adjustable output up 5V. An adjustable operating
frequency (up to 1.4MHz) is utilized to get optimum size,
cost, and efficiency.
RT9903B is available in VQFN-24L 4x4 package. Each
DC-DC converters have independent shutdown inputs.
Applications
z Digital Still Camera
z PDAs
z Portable Device
Features
zz
T wo step-up DC-DC Converters (CH1, CH2)
z
zz
``
`HV Internal Switches
``
``
`50mA Load Current
``
zz
z One Step-up DC-DC Converter (CH3)
zz
``
`0.2V Reference Voltage
``
``
`HV Internal Switches
``
``
`LED Brightness Dimming Control
``
``
`Over Voltage Protection
``
zz
z One Step-up DC-DC Converter (CH4)
zz
``
`External Switches
``
``
`External Current Limit Setting
``
zz
z Up to 1.4MHz Switching Frequency
zz
μμ
zz
z 1
μA Supply Current in Shutdown Mode
zz
μμ
zz
z External Compensation Network for All Converters
zz
zz
z Programm able Soft Start Function (CH1, CH2, CH3,
zz
CH4)
zz
z Independent Ena ble Pin to Shutdown Each Channel
zz
zz
z 24-Lead VQFN Package
zz
zz
z RoHS Compliant and 100% Lead (Pb)-Free
zz
Pin Configurations
Ordering Information
RT9903B
Package Type
QV : VQFN-24L 4x4 (V-Type)
Operating Temperature Range
P : Pb Free with Commercial Standard
Note :
RichTek Pb-free products are :
`RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
`Suitable for use in SnPb or Pb-free soldering processes.
`100% matte tin (Sn) plating.
Marking Information
For marking information, contact our sales representative
directly or through a RichTek distributor located in your
area, otherwise visit our website for detail.
NC
PGND
PGND
RT
EXT4
CS4
(TOP VIEW)
LX2
COMP2
24 2223
1
2
3
4
5
6
7
8 9 10 12
FB4
COMP4
VQFN-24L 4x4
FB2
21 20 19
GND
FB3
11
COMP3 AGND
COMP1
FB1
18
LX1
17
VDD
16
PGND
15
EN4
14
EN2
13
EN1
LX3
EN3
DS9903B-04 November 2005 www.richtek.com
1
RT9903B
Typical Application Circuit
2-AA Battery 1.8V to 3.2V
V
WLED
(12V)
3.3V_Motor
C5 to C8
10uFx4
R15
R5
1.2k
C10
4.7nF
BATT
10
300k
130k
R2
R3
C11
500pF
C3
10uF10uF
SS0520
Chip Enable
R6
C12
6.8nF
C1
10uF
D1
SS0520
C2
1uF
V
C4
D2
C9
1nF
R7
C13
56nF
BATT
L2
4.7uH
Si2302
L1
4.7uH
R1
R4
10k
Q1
R8
2.7k1.2k2.2k
C14
4.7nF
11
4
21
16
9
6
5
7
13
14
12
15
19
23
10
8
LX
3
RT
AGND
PGND
FB
3
CS4
EXT4
FB4
EN1
EN2
EN3
EN4
COMP1
COMP2
COMP3
COMP4
Preliminary
C15
4.7uF
17
VDD
RT9903B
PGND
LX1
FB1
LX2
FB2
NC
18
20
24
22
1
2, 3
C16
10uF
C19
10uF
V
NC
BATT
L3
4.7uH
D3
SS0520
R9
2.2M
L4
4.7uH
D4
SS0520
R11
5.1M
R12
360k
C24
2.2uF
C17
1nF
R10
200k
C21 to C23
C20
1nF
D5
BAT54WSPT
D6
ZENER
Diode
If -CCD = -6V, D6 = 5.6V_ZD
If -CCD = -8V, D6 = 3.6V_ZD
C18
10uF
10uFx3
+12V (+LCD)
R13
8.2k
C25
1uF
+15V (+CCD)
-6V (+CCD)
C26
10uF
DS9903B-04 November 2005www.richtek.com
2
WLED
(12V)
3.3V_Motor
C5 to C8
10uFx4
4.7nF
R5
1.2k
C10
V
R15
10
BATT
R2
300k
R3
130k
C11
500pF
SS0520
C2
1uF
C3
10uF10uF
SS0520
Chip Enable
R6
2.2k
C12
6.8nF
C4
D2
C9
1nF
C1
10uF
D1
R7
1.2k
C13
56nF
V
BATT
L1
4.7uH
R1
L2
4.7uH
R4
10k
Q1
Si2302
R8
2.7k
C14
4.7nF
11
4
21
16
9
6
5
7
13
14
12
15
19
23
10
8
V_3.3V
LX3
RT
AGND
PGND
FB3
CS4
EXT4
FB4
EN1
EN2
EN3
EN4
COMP1
COMP2
COMP3
COMP4
Preliminary
C15
4.7uF
17
VDD
RT9903B
PGND
LX1
FB1
LX2
FB2
NC
18
20
24
22
1
2, 3
C16
10uF
C19
10uF
NC
V
L3
4.7uH
BATT
L4
4.7uH
SS0520
D3
SS0520
R10
200k
C17
1nF
C21 to C23
10uFx3
C20
1nF
R9
2.2M
D4
R11
5.1M
R12
360k
D5
BAT54WSPT
C24
2.2uF
D6
ZENER
Diode
If -CCD = -6V, D6 = 5.6V_ZD
If -CCD = -8V, D6 = 3.6V_ZD
RT9903B
+12V (+LCD)
C18
10uF
+15V (+CCD)
C26
10uF
C25
1uF
R13
8.2k
-6V (+CCD)
Function Block Diagram
VDD
AGND
COMP1
COMP3
EN1
CH1
V-Mode
Step-Up
PWM
CH3
C-Mode
Step-Up
PWM
EN3
LX1
LX3
-
FB3
+
+
V
FB1
V
REF
0.2V
REF
1V
COMP4
COMP2
DS9903B-04 November 2005 www.richtek.com
EN2
CH2
V-Mode
Step-Up
PWM
CH4
C-Mode
Step-Up
PWM
EN4
EXT4
LX2 FB2
+
+
-
10uA
CS4
FB4
Oscillator
Soft
Start
Thermal
Protection
PGND (Exposed Pad)
RT
3
RT9903B
Preliminary
Functional Pin Description
Pin Number Pin Name Pin Function
1 NC No Connection
2 PGND Power Ground
3 PGND Power Ground
4 RT Frequency Setting Resistor Connection Pin
5 EXT4 CH4 External Power Switch
6 CS4 CH4 Current Sense Input Pin
7 FB4 CH4 Feedback Input
8 COMP4 CH4 Feedback Compensation Pin
9 FB3 CH3 Feedback Input
10 COMP3 CH3 Feedback Compensation Pin
11 LX3 CH3 Switch Node
12 EN3 CH3 Enable Input Pin
13 EN1 CH1 Enable Input Pin
14 EN2 CH2 Enable Input Pin
15 EN4 CH4 Enable Input Pin
16
17 VDD Power Input Pin
18 LX1 CH1 Switch Node
19 COMP1 CH1 Feedback Compensation Pin
20 FB1 CH1 Feedback Input
21 AGND Analog Ground
22 FB2 CH2 Feedback Input
23 COMP2 CH2 Feedback Compensation Pin
24 LX2 CH2 Switch Node
Exposed Pad GND Exposed pad should be soldered to PCB board and connected to GND.
PGND Power Ground
DS9903B-04 November 2005www.richtek.com
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Preliminary
Absolute Maximum Ratings (Note 1)
RT9903B
z Supply Input Voltage (V
z LX1, LX2, LX3 Pins ------------------------------------------------------------------------------------------------------- −0.3V to 20V
z Other I/O Pin Voltage ---------------------------------------------------------------------------------------------------
z Power Dissipation, P
) --------------------------------------------------------------------------------------------- −0.3 to 7V
DD
@ T
D
= 25°C
A
−0.3V to 7V
VQFN-24L 4x4 ------------------------------------------------------------------------------------------------------------ 1.923W
z Package Thermal Resistance (Note 3)
VQFN-24L 4x4, θJA------------------------------------------------------------------------------------------------------- 52°C/W
z Lead Temperature (Soldering, 10 sec.) ---------------------------------------------------------------------------- 260°C
z Operation Temperature Range --------------------------------------------------------------------------------------- −40°C to 85°C
z Junction Temperature Range ----------------------------------------------------------------------------------------- 0°C to 125°C
z Storage Temperature Range ------------------------------------------------------------------------------------------ −65°C to 150°C
Recommended Operating Conditions (Note 2)
z Maximum Output Voltage Setting ( V
z Dimming Control Frequency Range, CH3 ------------------------------------------------------------------------- 200Hz to 900Hz
OUT1
and V
) ---------------------------------------------------------- 17V
OUT2
Electrical Characteristics
(VDD =3.3V, TA = 25°C, unless otherwise specification)
Parameter Symbol Test Condition Min Typ Max Units
Supply Voltage
VDD Operating Voltage V
VDD Start-up Voltage VDD Pin Voltage 1.5 -- -- V
VDD Over Voltage Protection V
Supply Current
Shutdown Supply Current I
CH1 DC/DC Converter Supply
Current
CH2 DC/DC Converter Supply
Current
CH3 DC/DC Converter Supply
Current
CH4 DC/DC Converter Supply
Current
VDD Pin Voltage 2.4 -- 5.5 V
VDD
DD(OVP)
OFF
I
VDD1
I
VDD2
I
VDD3
I
VDD4
VDD Pin Voltage 6 -- -- V
VDD = 3.6V, V
V
=3.6V,
VDD
V
= V
FB1
V
EN1
V
EN3
V
VDD
V
FB2
V
EN1
V
EN3
V
VDD
V
FB3
V
EN1
V
EN3
V
VDD
V
FB4
V
EN1
V
EN3
REF
= 3.3V, V
= 0V, V
= 3.6V,
= V
REF
= 0V, V
= 0V, V
= 3.6V,
= V
REF
= 0V, V
= 3.3V, V
= 3.6V,
= V
REF
= 0V, V
= 0V, V
EN1 to 4
+ 0.15V
EN4
+ 0.15V
EN2
EN4
+ 0.15V
EN2
+ 0.15V
EN2
EN4
= 0V -- 0.01 1 μA
EN2
= 0V,
-- 200 250 μA
= 0V
= 3.3V,
-- 210 260 μA
= 0V
= 0V,
= 0V
EN4
= 0V,
-- 250 300 μA
-- 200 250 μA
= 3.3V
To be continued
DS9903B-04 November 2005 www.richtek.com
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