RT9953
4+1 CH Power Management IC
General Description
Features
The RT9953 is a complete power supply solution for digital
still cameras and other handheld devices. The RT9953 is
a multi-CH power management IC including one
synchronous step-up DC/DC converter, one selectable
synchronous step-up/step-down DC/DC converter, two
synchronous step-down DC/DC converters, and one low
dropout linear regulator.
z
One Synchronous Step-Up/Step-Down Selectable
Converter
z
Support 2AA or Li-ion Battery Applications
Internal Soft-Start Control
4 CHs with Internal Compensation
Power Switches Integrated
Up to 95% Efficiency
100% (max) Duty Cycle for Step-Down Converter
Adjustable Output Voltage
Fixed 1MHz Switching Frequency
LDO Works with Low-ESR Ceramic Capacitors
Fast Line/Load Transient Response
High PSRR Linear Regulator
RoHS Compliant and Halogen Free
z
z
z
z
z
z
z
z
Applications
z
Package Type
QW : WQFN-24L 4x4 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
FB2
EN4
SEL
24
23
22
21
20
19
LX1
1
18
LX2
PVDD1
2
17
PVDD2
EN3
3
16
VDDM
FB4
4
15
FB3
SS
5
14
EN2
PVDD4
6
13
PVDD3
GND
25
7
8
9
10
11
12
LX3
RT9953
(TOP VIEW)
FB5
Ordering Information
Pin Configurations
PVDD5
The RT9953 provides over current protection, thermal
shutdown protection, over voltage and under voltage
protection to achieve complete protection. The RT9953 is
available in the WQFN-24L 4x4 package.
z
CMOS Digital Still Camera
CMOS DV
Portable Devices
FB1
The RT9953 is designed to support Li+ and 2AA battery
applications. The selectable step-up/step-down converter
can be set by SEL pin. For the synchronous step-up and
step down converters, the efficiency can be up to 95%.
z
LX4
CH5 is a 500mA, low dropout, low noise linear regulator
with soft-start function.
GND
CH3 and CH4 are synchronous step-down outputs for DSP
core and memory power supply
z
EN5
CH2 is a selectable synchronous step-up/step-down
output for motor or DSC system I/O power
z
VOUT5
CH1 is a synchronous step-up output for motor or DSC
system I/O power
EN1
The RT9953 is designed to fulfill the applications for DSC
as follows :
z
WQFN-24L 4x4
Richtek products are :
`
RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.
`
Suitable for use in SnPb or Pb-free soldering processes.
DS9953-02 April 2011
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
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1
RT9953
Typical Application Circuit
For 2AA
RT9953
L2
2.2µH
V BAT
18 LX2
LX1 1
L1
2.2µH
V BAT
C4
10µF
V OUT_CH2
5V
C1
10µF
17 PVDD2
C5
10µF x 2
PVDD1 2
R3
470k
C3
4.7pF
21 FB2
FB1
VOUT_CH4
1.8V
C11
10µF
R2
133k
6 PVDD4
C10
10µF
R7
470k
L4
4.7µH
7 LX4
V BAT
LX3 12
C16
1µF
Chip Enable
3.6V
C7
10µF
L3
4.7µH
C9
22pF
19
16
3.6V
FB4
R5
768k
C8
10µF
V OUT_CH3
2.5V
FB3 15
R6
360k
SEL
VDDM
24 EN1
14 EN2
3 EN3
20
EN4
8 EN5
23, 25 (Exposed Pad) GND
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2
PVDD3 13
C12
33pF
4
R8
374k
R1
470k
V OUT_CH1
3.6V
22
R4
88.7k
3.6V
C2
10µF x 2
PVDD5 11
3.6V
C13
1µF
VOUT5 9
C15
10pF
FB5
R9
47k
C14
1µF
V OUT_CH5
2.5V
10
SS 5
C17
0.47nF
R10
22.1k
DS9953-02 April 2011
RT9953
For Li-ion
RT9953
17 PVDD2
VBAT
or 5V
C4
10µF
V OUT_CH2
3.3V
C5
10µF
R3
470k
L2
2.2µH
LX1 1
L1
2.2µH
V BAT
C1
10µF
18 LX2
PVDD1 2
C3
4.7pF
C6
10pF
21
FB2
FB1
R2
88.7k
6 PVDD4
V BAT
VOUT_CH4
1.8V
C11
10µF
R7
470k
L4
4.7µH
7 LX4
PVDD3 13
R8
374k
C9
22pF
19
16
5V
C16
1µF
Chip Enable
V BAT
C7
10µF
L3
4.7µH
LX3 12
C12
33pF
4
FB4
VDDM
24 EN1
14 EN2
R5
768k
C8
10µF
V OUT_CH3
2.5V
FB3 15
R6
360k
SEL
3 EN3
20
EN4
8 EN5
23, 25 (Exposed Pad) GND
PVDD5 11
V BAT
C13
1µF
VOUT5 9
C15
10pF
FB5
R9
47k
C14
1µF
V OUT_CH5
2.5V
10
SS 5
C17
0.47nF
DS9953-02 April 2011
R1
470k
V OUT_CH1
5V
22
R4
150k
C10
10µF
C2
10µF x 2
R10
22.1k
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3
RT9953
Table 1. Recommended Components for the Typical Application Circuit
Channel
CH3
Formula
V OUT_CH3 = (1+R5/R6) x 0.8
VOUT_CH3 (V)
3.3
2.5
1.8
1.5
1.3
1.2
1.0
L3 (µH)
4.7
4.7
4.7
4.7
4.7
4.7
4.7
R5 (kΩ)
86.6
768
470
330
237
187
23.2
R6 (kΩ)
27.4
360
374
374
374
374
93.1
C9 (pF)
22
22
33
47
68
82
47
C8 (µF)
10
10
10
10
10
10
10
Channel
CH4
Application
V OUT_CH4 = (1+R7/R8) x 0.8
VOUT_CH4 (V)
3.3
2.5
1.8
1.5
1.3
1.2
1.0
L4 (µH)
4.7
4.7
4.7
4.7
4.7
4.7
4.7
R7 (kΩ)
86.6
768
470
330
237
187
23.2
R8 (kΩ)
27.4
360
374
374
374
374
93.1
C12 (pF)
22
22
33
47
68
82
47
C11 (µF)
10
10
10
10
10
10
10
Channel
CH5
Formula
V OUT_CH5 = (1+R9/R10) x 0.8
VOUT_CH5 (V)
2.5
R9 (kΩ)
47
R10 (kΩ)
22.1
C15 (pF)
10
C14 (µF)
1
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4
DS9953-02 April 2011
RT9953
Functional Pin Description
Pin No.
Pin Name
Pin Function
1
LX1
Switch Node of CH1. High impedance in shutdown mode.
2
PVDD1
Power Input of CH1.
3
EN3
Enable Control Input of CH3.
4
FB4
Feedback Input of CH4. High impedance in shutdown mode.
5
SS
Soft-Start Control Input.
6
PVDD4
Power Input of CH4.
7
LX4
Switch Node of CH7. High impedance in shutdown mode.
8
EN5
Enable Control Input of CH5.
9
VOUT5
Output Voltage of CH5.
10
FB5
Feedback Input of CH5. High impedance in shutdown mode.
11
PVDD5
Power Input of CH5.
12
LX3
Switch Node of CH3. High impedance in shutdown mode.
13
PVDD3
Power Input of CH3.
14
EN2
Enable Control Input of CH2.
15
FB3
Feedback Input of CH3. High impedance in shutdown mode.
16
VDDM
Analog Power Input.
17
PVDD2
Power Input of CH2.
18
LX2
19
SEL
20
EN4
Switch Node of CH2. High impedance in shutdown mode.
Selection Input for CH2 step-up or step-down operation mode. Logic state can
not be changed during operation.
Enable Control Input of CH4.
21
FB2
Feedback Input of CH2. High impedance in shutdown mode.
22
FB1
23,
GND
25 (Exposed Pad)
24
EN1
DS9953-02 April 2011
Feedback Input of CH1. High impedance in shutdown mode.
Ground Pin. The exposed pad must be soldered to a large PCB and connected to
GND for maximum thermal dissipation.
Enable Control Input of CH1.
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5
RT9953
Function Block Diagram
VDDM
PVDD2
PVDD1
CH2
C-Mode
Step-Up or
Step-Down
LX2
CH1
C-Mode
Step-Up
+
FB2
LX1
+
0.8V
REF
FB1
0.8V
REF
PVDD4
PVDD3
CH4
C-Mode
Step-Down
LX4
CH3
C-Mode
Step-Down
+
FB4
0.8V
REF
LX3
+
FB3
0.8V
REF
VDDM
Enable Mode
Sequence
PVDD5
SS
CH5
LDO
VOUT5
EN1
EN2
EN3
EN4
EN5
SEL
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6
+
FB5
0.8V
REF
GND
DS9953-02 April 2011
RT9953
Absolute Maximum Ratings
(Note 1)
Supply Voltage, VDDM, PVDD5 -------------------------------------------------------------------------------------- 0.3V to 7V
Power Switch :
LX1, LX2, LX3, LX4------------------------------------------------------------------------------------------------------- −0.3V to 6.5V
l The Other Pins ----------------------------------------------------------------------------------------------------------- −0.3V to 6.5V
l Power Dissipation, PD @ TA = 25°C
WQFN 24L 4x4 ----------------------------------------------------------------------------------------------------------- 1.852W
l Package Thermal Resistance (Note 2)
WQFN 24L 4x4, θJA ----------------------------------------------------------------------------------------------------- 54°C/W
WQFN 24L 4x4, θJC ----------------------------------------------------------------------------------------------------- 7°C/W
l Junction Temperature --------------------------------------------------------------------------------------------------- 150°C
l Lead Temperature (Soldering, 10 sec.)------------------------------------------------------------------------------ 260°C
l Storage Temperature Range ------------------------------------------------------------------------------------------- −65°C to 150°C
l ESD Susceptibility (Note 3)
HBM (Human Body Mode) --------------------------------------------------------------------------------------------- 2kV
MM (Machine Mode) ---------------------------------------------------------------------------------------------------- 200V
l
l
Recommended Operating Conditions
l
l
(Note 4)
Junction Temperature Range ------------------------------------------------------------------------------------------ −40°C to 125°C
Ambient Temperature Range ------------------------------------------------------------------------------------------ −40°C to 85°C
Electrical Characteristics
(VDDM = 3.3V, TA = 25°C, unless otherwise specified)
Parameter
Symbol
Test Conditions
Min
Typ
M ax
Unit
Supply Voltage
VDDM Operating Voltage
V DDM
2.7
--
5.5
V
VDDM Startup Voltage
V ST
1.5
--
--
V
5.7
6
6.25
V
2.5
--
5.5
V
VDDM Over Voltage Protection
PVDD5 Operating Voltage
V PVDD5
Supply Current
Shutdown Supply Current into VDDM
CH1 (Syn Step-Up) : Supply Current
into VDDM
IOFF
All EN = 0
--
--
0.1
µA
IQ1
Non Switching, EN1 = 3.3V
--
--
800
µA
IQ2
Non Switching, EN2 = 3.3V
--
--
800
µA
IQ3
Non Switching, EN3 = 3.3V
--
--
800
µA
IQ4
Non Switching, EN4 = 3.3V
--
--
800
µA
IQ5
EN5 = 3.3V, IOUT = 0mA
--
90
130
µA
CH2 (Syn Step-Up or Syn
Step-Down) : Supply Current into
VDDM
CH3 (Syn Step-Down) :
Supply Current into VDDM
CH4 (Syn Step-Down) :
Supply Current into VDDM
CH5 (LDO) :
Supply Current into PVDD5
To be continued
DS9953-02 April 2011
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7
RT9953
Parameter
Min
Typ
Max
Unit
VFB1 = 0.7V
900
80
1000
83
1100
86
kHz
%
CH2 Maximum Duty Cycle (Step-Up)
VFB2 = 0.7V
80
83
86
%
CH2 Maximum Duty Cycle
(Step-Down)
VFB2 = 0.7V
--
--
100
%
VFB3 = 0.7V
--
--
100
%
VFB4 = 0.7V
--
--
100
%
0.788
0.8
0.812
V
−3
--
3
%
P-MOSFET, PVDD1 = 3.3V
--
200
250
N-MOSFET, PVDD1 = 3.3V
--
150
200
Oscillator
CH1,2,3,4 Operating Frequency
CH1 Maximum Duty Cycle (Step-Up)
Symbol
Test Conditions
fOSC
CH3 Maximum Duty Cycle
(Step-Down)
CH4 Maximum Duty Cycle
(Step-Down)
Feedback Regulation Voltage
Feedback Regulation Voltage @ FB1,
FB2, FB3, FB4, FB5
Total Accuracy (Including load
regulation and line regulation)
Power Switch
CH1 On Resistance of MOSFET
RDS(ON)
CH1 Current Limitation (Step-Up)
mΩ
--
3
--
P-MOSFET, PVDD2 = 3.3V
--
200
250
N-MOSFET, PVDD2 = 3.3V
--
150
200
CH2 Current Limitation (Step-Down)
--
1.8
--
A
CH2 Current Limitation (Step-Up)
--
3
--
A
CH2 On Resistance of MOSFET
CH3 On Resistance of MOSFET
RDS(ON)
R
P-MOSFET, PVDD3 = 3.3V
--
350
400
DS(ON)
N-MOSFET, PVDD3 = 3.3V
--
300
400
--
1.5
--
CH3 Current Limitation (Step-Down)
CH4 On Resistance of MOSFET
mΩ
mΩ
A
R
P-MOSFET, PVDD4 = 3.3V
--
350
400
DS(ON)
N-MOSFET, PVDD4 = 3.3V
--
300
400
--
1.5
--
--
160
320
V Dro p
2.2V ≦ PVDD5 ≦ 2.7V,
IOUT = 400mA
2.7V ≦ PVDD5 ≦ 5.5V,
IOUT = 500mA
--
250
400
5.7
6
6.25
V
--
0.5
--
V
FB Threshold
0.36
0.4
0.44
V
2.2V ≦ PVDD5 ≦ 2.7V
0.4
0.7
1.05
2.7V ≦ PVDD5 ≦ 5.5V
0.5
0.8
1.05
--
100
--
CH4 Current Limitation (Step-Down)
CH5 Dropout Voltage (LDO)
A
mΩ
A
mV
Protection
Over Voltage Protection of CH1, CH2
Step-Up, PVDD1 and PVDD2
Over Voltage Protection Hysteresis of
CH1, CH2 Step-Up, PVDD1 and
PVDD2
Under Voltage Protection (CH1 to
CH5)
CH5 Current Limit
Protection Fault Delay
ILIM
A
ms
To be continued
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8
DS9953-02 April 2011
RT9953
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
Control
EN1 to EN5, SEL
Logic High
1.3
--
5.5
V
Input Threshold
Logic Low
--
--
0.4
V
EN1 to EN5, SEL Sink Current
--
2
6
µA
--
--
0.3
%
--
--
0.6
%
CH5 LDO Regulation
V PVDD5 = (VOUT5 + 1V) to 5.5V
Line Regulation
ΔVLINE
Load Regulation
ΔVLOAD
1mA < IOUT < 300mA
PSRR
COUT = 1uF, IOUT = 100mA
Power Supply
f = 100Hz
Rejection Rate
f = 10kHz
IOUT = 1mA
--
−60
--
--
−30
--
125
160
--
°C
--
20
--
°C
dB
Thermal Protection
Thermal Shutdown
T SD
Thermal Shutdown Hysteresis
ΔT SD
Note 1. Stresses listed as the above “ Absolute Maximum Ratings” may cause permanent damage to the device. These
are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated
in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions
for extended periods may remain possibility to affect device reliability.
Note 2. θJA is measured in the natural convection at TA = 25°C on a high effective four layers thermal conductivity test
board of JEDEC 51-7 thermal measurement standard. The case point of θJC is on the expose pad for the WQFN
package.
Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
DS9953-02 April 2011
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9
RT9953
Typical Operating Characteristics
CH1 Step-Up Efficiency vs. Output Current
CH1 Step-Up Efficiency vs. Output Current
100
100
VBAT
VBAT
VBAT
VBAT
VBAT
VBAT
Efficiency (%)
80
70
60
50
=
=
=
=
=
=
90
4.5V
4.2V
3.9V
3.6V
3.3V
3V
80
Efficiency (%)
90
40
30
20
VBAT
VBAT
VBAT
VBAT
VBAT
VBAT
70
60
50
40
30
VDDM = 3V, VOUT_CH1 = 5V,
L1 = 2.2µH, C2 = 10µFx2
10
0
0
10
100
1000
10
100
Output Current (mA)
CH2 Step-Up Efficiency vs. Output Current
100
90
90
80
80
70
70
VBAT
VBAT
VBAT
VBAT
VBAT
VBAT
50
40
30
=
=
=
=
=
=
Efficiency (%)
100
60
1000
Output Current (mA)
CH2 Step-Down Efficiency vs. Output Current
Efficiency (%)
3.4V
3V
2.7V
2.5V
2.2V
1.8V
20
VDDM = 5V, VOUT_CH1 = 5V,
L1 = 2.2µH, C2 = 10µFx2
10
1.8V
3V
3.3V
3.6V
4.2V
4.5V
20
VBAT
VBAT
VBAT
VBAT
VBAT
VBAT
60
50
40
=
=
=
=
=
=
3V
2.7V
2.5V
2.2V
2V
1.8V
30
20
VDDM = 5V, VOUT_CH2 = 1.2V,
L2 = 4.7µH, C5 = 10µF
10
VDDM = 3V, VOUT_CH2 = 3.3V,
L2 = 2.2µH, C5 = 10µFx2
10
0
0
10
100
10
1000
100
CH3 Step-Down Efficiency vs. Output Current
CH3 Step-Down Efficiency vs. Output Current
100
100
90
90
80
80
VBAT
VBAT
VBAT
VBAT
VBAT
VBAT
60
50
40
=
=
=
=
=
=
2.7V
3.3V
3.6V
3.9V
4.2V
4.5V
Efficiency (%)
70
1000
Output Current (mA)
Output Current (mA)
Efficiency (%)
=
=
=
=
=
=
30
20
70
VBAT
VBAT
VBAT
VBAT
VBAT
VBAT
60
50
40
30
=
=
=
=
=
=
1.8V
2.5V
3V
3.3V
3.6V
4.5V
20
VDDM = 5V, VOUT_CH3 = 1.8V,
L3 = 4.7µH, C8 = 10µF
10
0
VDDM = 5V, VOUT_CH3 = 1.2V,
L3 = 4.7µH, C8 = 10µF
10
0
10
100
Output Current (mA)
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10
1000
10
100
1000
Output Current (mA)
DS9953-02 April 2011
RT9953
CH4 Step-Down Efficiency vs. Output Current
CH4 Step-Down Efficiency vs. Output Current
100
100
90
90
Efficiency (%)
80
70
60
=
=
=
=
=
3.4V
3.6V
3.9V
4.2V
4.5V
80
Efficiency (%)
VBAT
VBAT
VBAT
VBAT
VBAT
50
40
30
20
70
VBAT
VBAT
VBAT
VBAT
VBAT
VBAT
60
50
40
30
=
=
=
=
=
=
1.8V
2.5V
3V
3.3V
3.6V
4.5V
20
VDDM = 5V, VOUT_CH4 = 3.3V,
L4 = 4.7µH, C11 = 10µF
10
VDDM = 3V, VOUT_CH4 = 1.2V,
L4 = 4.7µH, C11 = 10µF
10
0
0
10
100
1000
10
100
Output Current (mA)
1000
Output Current (mA)
CH1 Step-Up Output Voltage vs. Output Current
CH2 Step-Down Output Voltage vs. Output Current
5.000
1.210
4.995
1.208
4.985
VBAT = 3V
4.980
VBAT = 4.5V
4.975
4.970
4.965
Output Voltage (V)
Output Voltage (V)
4.990
1.205
1.203
1.200
VBAT = 3V
VBAT = 4.5V
1.198
1.195
4.960
1.193
4.955
VDDM = 5V
VDDM = 5V
4.950
1.190
0
100
200
300
400
500
600
0
200
Output Current (mA)
600
800
1000
CH3 Step-Down Output Voltage vs. Output Current
3.45
1.85
3.40
1.84
3.35
3.30
VBAT = 1.8V
VBAT = 3V
3.20
Output Voltage (V)
Output Voltage (V)
CH2 Step-Up Output Voltage vs. Output Current
3.25
400
Output Current (mA)
1.83
1.82
VBAT = 4.5V
VBAT = 3V
VBAT = 2.7V
1.81
1.80
1.79
VDDM = 3V
VDDM = 5V
1.78
3.15
0
100
200
300
400
Output Current (mA)
DS9953-02 April 2011
500
600
0
100
200
300
400
500
600
Output Current (mA)
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11
RT9953
CH4 Step-Down Output Voltage vs. Output Current
CH1 Output Voltage Ripple
3.50
Output Voltage (V)
3.45
3.40
LX1
(2V/Div)
3.35
VBAT = 4.5V
VBAT = 5V
3.30
VOUT_CH1_ac
(10mV/Div)
3.25
3.20
VDDM = 5V, VBAT = 3.7V, VOUT_CH1 = 5V,
IOUT = 300mA, L1 = 2.2μH, C2 = 10μFx2
VDDM = 5V
3.15
0
100
200
300
400
500
Time (500ns/Div)
600
Output Current (mA)
CH2 Step-Down Output Voltage Ripple
CH2 Step-Up Output Voltage Ripple
LX2
(2V/Div)
LX2
(2V/Div)
VOUT_CH2_ac
(5mV/Div)
VOUT_CH2_ac
(10mV/Div)
VDDM = 5V, VBAT = 3.7V, VOUT_CH2 = 1.2V,
IOUT = 300mA, L2 = 2.2μH, C5 = 10μF
VDDM = 3V, VBAT = 1.8V, VOUT_CH2 = 3.3V,
IOUT = 300mA, L2 = 2.2μH, C5 = 10μFx2
Time (500ns/Div)
Time (500ns/Div)
CH3 Output Voltage Ripple
CH4 Output Voltage Ripple
LX3
(2V/Div)
LX4
(2V/Div)
VOUT_CH3_ac
(5mV/Div)
VOUT_CH4_ac
(5mV/Div)
VDDM = 5V, VBAT = 3.7V, VOUT_CH3 = 1.8V,
IOUT = 300mA, L3 = 4.7μH, C8 = 10μF
Time (500ns/Div)
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12
VDDM = 5V, VBAT = 4.2V, VOUT_CH4 = 3.3V,
IOUT = 300mA, L4 = 4.7μH, C11 = 10μF
Time (500ns/Div)
DS9953-02 April 2011
RT9953
CH2 Step-Down Load Transient Response
CH1 Load Transient Response
I LOAD
(200mA/Div)
I LOAD
(200mA/Div)
V OUT_CH1_ac
(100mV/Div)
V OUT_CH2_ac
(50mV/Div)
VDDM = 5V, VBAT = 3.7V, VOUT_CH2 = 1.2V,
IOUT = 100mA to 400mA, L2 = 2.2μH, C5 = 10μF
VDDM = 5V, VBAT = 3V, VOUT_CH1 = 5V,
IOUT = 100mA to 400mA, L1 = 2.2μH, C2 = 10μFx2
Time (1ms/Div)
Time (1ms/Div)
CH3 Load Transient Response
CH2 Step-Up Load Transient Response
I LOAD
(200mA/Div)
I LOAD
(200mA/Div)
V OUT_CH2_ac
(100mV/Div)
V OUT_CH3_ac
(50mV/Div)
VDDM = 3V, VBAT = 1.8V, VOUT_CH2 = 3.3V,
IOUT = 100mA to 400mA, L2 = 2.2μH, C5 = 10μFx2
VDDM = 5V, VBAT = 3.7V, VOUT_CH3 = 1.8V,
IOUT = 50mA to 300mA, L3 = 4.7μH, C8 = 10μF
Time (1ms/Div)
Time (1ms/Div)
Frequency vs. Temperature
CH4 Load Transient Response
1050
1030
Frequency (kHz)
1010
I LOAD
(200mA/Div)
V OUT_CH4_ac
(50mV/Div)
990
970
950
930
910
890
VDDM = 5V, VBAT = 3.7V, VOUT_CH4 = 3.3V,
IOUT = 50mA to 300mA, L4 = 4.7μH, C11 = 10μF
870
VDDM = 3V, VBAT = 3V
850
Time (1ms/Div)
-40 -30 -20 -10 0
10 20 30 40 50 60 70 80 90
Temperature (°C)
DS9953-02 April 2011
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RT9953
CH5 LDO Dropout Voltage vs. Output Current
0.45
2.54
0.40
2.53
0.35
2.52
2.51
2.50
VBAT = 3V
VBAT = 4.5V
2.49
2.48
2.47
2.46
Dropout Voltage (V)
Output Voltage (V)
CH5 LDO Output Voltage vs. Output Current
2.55
0
100
200
300
400
500
25°C
0.30
0.25
−40°C
0.20
0.15
0.10
0.05
VDDM = 5V
2.45
90°C
VDDM = 5V, C14 = 1μF
0.00
600
0
100
Output Current (mA)
200
300
400
500
Output Current (mA)
CH5 LDO Load Transient Response
CH5 LDO Output Voltage vs. Temperature
2.55
2.54
Output Voltage (V)
2.53
I LOAD
(200mA/Div)
V OUT_CH5_ac
(10mV/Div)
2.52
2.51
2.50
VBAT = 4.5V
2.49
2.48
VBAT = 3V
2.47
VDDM = 5V, VBAT = 3.7V, VOUT_CH5 = 2.5V,
IOUT = 1mA to 300mA, C14 = 1μF
2.46
2.45
Time (1ms/Div)
VDDM = 5V, C14 = 1μF, IOUT = 300mA
-40 -30 -20 -10 0
10 20 30 40 50 60 70 80 90
Temperature (°C)
CH5 LDO PSRR
0
CH5 LDO IPVDD5 Quiescent Current vs. Temperature
130
-10
Quiescent Current (μA)
120
PSRR (dB)
-20
-30
-40
-50
VBAT = 5V
VBAT = 3.7V
-60
110
100
90
80
70
60
50
40
-70
VDDM = 5V, C14 = 1μF, IOUT = 100mA
-80
10
100
1000
10000
Frequency (Hz)
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14
100000
1000000
30
VDDM = 3.3V, VBAT = 3.3V, C14 = 1μF, IOUT = 0mA
-40 -30 -20 -10 0
10 20 30 40 50 60 70 80 90
Temperature (°C)
DS9953-02 April 2011
RT9953
Application information
The RT9953 includes the following four DC/DC converters
and one LDO to build a multiple-output power-supply
system.
CH1 : Synchronous Step-Up DC/DC Converter
The CH1 is a synchronous step-up converter for motor or
DSC system I/O power. The converter operates at fixed
frequency and PWM Current Mode. The CH1 converter
integrated internal MOSFETs, compensation network and
synchronous rectifier for up to 95% efficiency.
The output voltage can be set by the following equation :
VOUT_CH1 = (1+R1/R2) x VFB1
Step-Down :
The converter operates at fixed frequency PWM mode
and continuous current mode (CCM) with internal
MOSFETs, compensation network and synchronous
rectifier for up to 95% efficiency. The CH2 Step-down
converter can be operating at 100% maximum duty cycle
to extend the input operating voltage range. While the
input voltage is close to the output voltage, the converter
enters low dropout mode.
The output voltage can be set by the following equation :
VOUT_CH2 = (1+R3/R4) x VFB2
Where VFB2 is 0.8V typically.
Where VFB1 is 0.8V typically.
CH2 : Synchronous Step-Up or Step-Down
Selectable DC/DC Converter
The CH2 is a synchronous step-up/step-down selectable
converter for motor or DSC system I/O power.
Mode setting
The CH2 of RT9953 features flexible Step-up or Step-down
topology setting for either 1 x Li-ion or 2 x AA application
by SEL pin. Please refer to “Electrical Characteristics”
for level of Logic-High or Logic-Low. When the CH2
operates as a Step-up converter, the SEL must be set at
Logic-High. If the CH2 operates at Step-down mode, the
SEL must be set at Logic-Low. In addition, please note
that the logic state can not be changed during operation.
Table 2. CH2 Mode Setting
SEL
CH2 Operating Mode
Logic-High
Step-Up
Logic-Low
Step-Down
Step-Up :
The converter operates at fixed frequency PWM Mode,
continuous current mode (CCM), and discontinuous current
mode (DCM) with internal MOSFETs, compensation
network and synchronous rectifier for up to 95% efficiency.
CH3 and CH4 : Synchronous Step-Down DC/DC
Converter
The converter operates at fixed frequency PWM mode,
CCM and integrated internal MOSFETs and compensation
network. The CH3 and CH4 Step-down converter can be
operating at 100% maximum duty cycle to extend battery
operating voltage range. When the input voltage is close
to the output voltage, the converter could enter low dropout
mode with low output ripple.
The output voltage can be set by the following equation :
VOUT_CH3 = (1+R5/R6) x VFB3
VOUT_CH4 = (1+R7/R8) x VFB4
Where VFB3 and VFB4 is 0.8V typically.
CH5 : 500mA Low Dropout, Low Noise Linear
Regulator
Like any low-dropout regulator, this CH requires input and
output decoupling capacitors. The CH5 linear regulator
can support 500mA output current when PVDD5 > 2.7V.
The typical current limit is 0.8A. If the output is shorted to
ground, the Under Voltage Protection function will be
triggered to shutdown the IC to prevent the part from
damaging.
The output voltage can be set by the following equation :
VOUT_CH5 = (1+R9/R10) x VFB5
Where VFB5 is 0.8V typically.
DS9953-02 April 2011
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RT9953
Thermal Considerations
Layout Considerations
For continuous operation, do not exceed absolute
maximum operation junction temperature. The maximum
power dissipation depends on the thermal resistance of
IC package, PCB layout, the rate of surroundings airflow
and temperature difference between junction to ambient.
The maximum power dissipation can be calculated by
following formula :
For the best performance of the RT9953, the following
PCB layout guidelines must be strictly followed :
PD(MAX) = (TJ(MAX) − TA ) / θJA
Where T J(MAX) is the maximum operation junction
temperature, TA is the ambient temperature and the θJA is
the junction to ambient thermal resistance.
For recommended operating conditions specification of
RT9953, the maximum junction temperature is 125°C. The
junction to ambient thermal resistance θJA is layout
dependent. For WQFN-24L 4x4 package, the thermal
resistance θJA is 54°C/W on the standard JEDEC 51-7
four layers thermal test board. The maximum power
dissipation at TA = 25°C can be calculated by following
formula :
}
Place the input and output capacitors as close as
possible to the input and output pins respectively for
good filtering.
}
Keep the main power traces as wide and short as
possible.
}
The switching node area connected to LX and inductor
should be minimized for lower EMI.
}
Place the feedback components as close as possible
to the FB pin and keep these components away from
the noisy devices.
}
Connect the GND and Exposed Pad to a strong ground
plane for maximum thermal dissipation and noise
protection.
}
CH5 PCB trace and component had put different PCB
side to avoid LX3 and LX4 switching noise.
PD(MAX) = (125°C − 25°C) / (54°C/W) = 1.852W for
WQFN-24L 4x4
The maximum power dissipation depends on operating
ambient temperature for fixed T J(MAX) and thermal
resistance θJA. For RT9953 package, the Figure 1 of
derating curve allows the designer to see the effect of
rising ambient temperature on the maximum power
dissipation allowed.
Maximum Power Dissipation (W)
2.0
Four Layers PCB
1.8
1.6
1.4
WQFN-24L 4x4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 1. Derating Curves for RT9953 Package
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DS9953-02 April 2011
RT9953
Place the feedback components as
LX should be connected to Inductor by
close as possible to the FB pin and
wide and short trace, keep sensitive
keep away from noisy devices.
compontents away from this trace
V OUT2_CH2
GND
C3 R1 C6 R3
V BAT
GND
C1
R2
C2
GND
FB1
FB2
EN4
SEL
19
L2
1
18
LX2
2
17
PVDD2
EN3
3
FB4
4
SS
5
PVDD4
6
L4
7
8
9
10
11
12
FB5
PVDD5
LX3
25
C15
16
VDDM
15
FB3
14
EN2
13
PVDD3
R9
C4
V BAT
C16
R5
C9
R6
V BAT
C7
GND
L3
C8
R10
VBAT
C11
GND
VOUT5
C17
C10
V OUT4_CH4
20
LX1
V BAT
GND
21
LX4
Input/Output
capacitors must
be placed as
close as possible
to the Input/
Output pins.
22
PVDD1
R8
C12
23
EN5
R7
24
VOUT5_CH5
V OUT1_CH1
EN1
L1
GND
C5
R4
C14
GND
C13
V OUT3_CH3
Connect the Exposed
Pad to a ground plane.
Figure 2. PCB Layout Guide
DS9953-02 April 2011
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RT9953
Table 3. Protection Items
Threshold (typical)
Protection methods
Refer to Electrical spec
VDDM
CH1
Step-Up
CH2
Step-Up
Protection
type
Over Voltage
VDDM > 6V
Protection
Current Limit N-MOSFET current > 3A
Delay
time
Disable all channels
100ms
IC shutdown
100ms
PVDD1 OVP PVDD1 > 6V
IC shutdown
No-delay VDDM power reset
Current Limit N-MOSFET current > 3A
IC shutdown
100ms
PVDD2 OVP PVDD2 > 6V
IC shutdown
No-delay VDDM power reset
Reset method
Restart if VDDM < 5.5V
(with hysteresis)
VDDM power reset
VDDM power reset
OCP
CH2
Step-Down UVP
P-MOSFET current > 1.5A
IC shutdown
100ms
VDDM power reset
FB2 < 0.4V
IC shutdown
100ms
VDDM power reset
OCP
CH3
Step-Down UVP
P-MOSFET current > 1.5A
IC shutdown
100ms
VDDM power reset
FB3 < 0.4V
IC shutdown
100ms
VDDM power reset
OCP
CH4
Step-Down UVP
P-MOSFET current > 1.5A
IC shutdown
100ms
VDDM power reset
100ms
VDDM power reset
CH5 LDO
Thermal
FB4 < 0.4V
IC shutdown
IOUT (P-MOSFET current) >
Current Limit
Current Limiting
0.8A
UVP
FB5 < 0.4V
IC shutdown
Thermal
All channels stop
Temperature > 160°C
shutdown
switching
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No-delay No reset
100ms
VDDM power reset
100ms
Temperature < 140°C
DS9953-02 April 2011
RT9953
Outline Dimension
D2
D
SEE DETAIL A
L
1
E
E2
e
1
2
DETAIL A
b
Pin #1 ID and Tie Bar Mark Options
A
A3
Note : The configuration of the Pin #1 identifier is optional,
but must be located within the zone indicated.
A1
Symbol
1
2
Dimensions In Millimeters
Dimensions In Inches
Min
Max
Min
Max
A
0.700
0.800
0.028
0.031
A1
0.000
0.050
0.000
0.002
A3
0.175
0.250
0.007
0.010
b
0.180
0.300
0.007
0.012
D
3.950
4.050
0.156
0.159
D2
2.300
2.750
0.091
0.108
E
3.950
4.050
0.156
0.159
E2
2.300
2.750
0.091
0.108
e
L
0.500
0.350
0.020
0.450
0.014
0.018
W-Type 24L QFN 4x4 Package
Richtek Technology Corporation
Richtek Technology Corporation
Headquarter
Taipei Office (Marketing)
5F, No. 20, Taiyuen Street, Chupei City
5F, No. 95, Minchiuan Road, Hsintien City
Hsinchu, Taiwan, R.O.C.
Taipei County, Taiwan, R.O.C.
Tel: (8863)5526789 Fax: (8863)5526611
Tel: (8862)86672399 Fax: (8862)86672377
Email: marketing@richtek.com
Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit
design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be
guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek.
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