Application Note: SA22300
36V, Boost/Flyback/Sepic Controller
General Description
Key Features
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The SA22300 is available in a SOP8 package.
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The SA22300 integrates a gate driver to drive
external N-channel MOSFET and also adopts peak
current control strategy with built-in slope
compensation to improve the stability.
Wide Input Voltage Range: 3.45V to 36V
1.2V ±2% Reference Voltage
Fixed Frequency Operation
Internal Soft-Start
Typical 1.6μA Shutdown Current
Cycle-by-Cycle Current Limit Protection
Hiccup-Mode Overcurrent Protection (OCP)
Hiccup-Mode Short-Circuit Protection (SCP)
1.5A Peak Gate Source Current
1.5A Peak Gate Sink Current
Thermal Shutdown
Package: SOP8
Automotive AEC- Q100 Grade 1 Certified
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The SA22300 is a non-synchronous Boost/Flyback/
Sepic controller with built-in protection features. The
device is suitable for harsh automotive environment.
It features several built-in protection such as cycleby-cycle current limit, overcurrent protection, FB
short protection, etc.
Ordering Information
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Applications
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SA22300 □(□□ □)
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Automotive 12-V Battery Application
DC-to-DC Converters
LIDAR Power Supply
Battery-powered Boost, Flyback, Sepic
Note
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Package Type
SOP8
fi
Ordering Number
SA22300FAP
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Package Code
Optional Spec Code
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Typical Application Circuit
RFB1
Co
CIN
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VSUPPLY
VOUT
CO
RO
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VIN
Q
GATE
EN
RFB2
le
RGS
ISEN
Si
RSEN
GND
FB
COMP
Rz
Cz
VCC
CVCC
Figure 1. Boost Application
AN_SA22300 Rev. 0.9
© 2023 Silergy Corp.
Silergy Corp. Confidential- Prepared for Customer Use Only
1
All Rights Reserved.
SA22300
VSUPPLY
D
1：N
VOUT
CIN
CO
RO
VIN
Q
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GATE
EN
RGS
RSEN
r
ISEN
Fo
RFB1
GND
FB
COMP
RFB2
d
Rz
Cz
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VCC
Pr
ep
CVCC
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Figure 2. Flyback Application
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VSUPPLY
*
*
Coupling L
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CIN
D
on
VIN
.C
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AN_SA22300 Rev. 0.9
© 2023 Silergy Corp.
RFB1
CO
RO
RGS
RSEN
Co
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Si
Cz
C1
ISEN
RFB2
GND
COMP
Rz
Q
GATE
EN
VOUT
FB
VCC
CVCC
Figure 3. Sepic Application
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2
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SA22300
Block Diagram
LDO
enable_LDO
VCC2
EN_OK
LDO2
VBG
bandgap
FB
-
SCP
VREF
VCC
Vscp
+
VREF
Vth
Select
+
+
gm_ea
-
Burst_mode
-
logic
GATE
S Q
clock
ep
SS
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e
d
VCC2
Fo
r
+
-
VEN _H
Power_Ready
EN_OK
VIN_OK
OTP
EN
VCC_OK
+
-
VVCC_R
i
VIN_OK
+
-
VUVLO_R
VCC
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VIN
VCC2
R
Pr
Shutdown
IFB_PU
GND
Min_Ton
FB
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ia
COMP
+
+
fi
on
SLOPE
rp
Peak_limit
GND
+
Oneshot
clock
Hiccup
Timer
OTP
Power_ready
+
-
VCL
SCP
OCP
+
-
150%VCL
Thermal
sensor
165
Figure 4. Block Diagram
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Shutdown
ISEN
+
Acsa
-
Max_
D
.C
Oscillator
IIS EN_PU
+
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Shutdown
nt
High clamp
&Low clamp
VCC2
Shutdown
Peak_limit
Max_D
-
AN_SA22300 Rev. 0.9
© 2023 Silergy Corp.
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3
All Rights Reserved.
SA22300
Pin-Out (Top View)
EN 1
7 COMP
GND 3
6 VIN
GATE 4
5 VCC
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ISEN 2
i
8 FB
2
GND
3
GATE
4
VCC
5
VIN
6
COMP
7
FB
8
Pr
ISEN
Pin Description
Enable pin, apply logic high signal to enable the device.
Current sense input pin. Voltage generated across an external sense resistor is fed into
this pin.
Ground pin.
Gate driver output. Connect to the gate of the external N-channel MOSFET. GATE pin
will turn into high impedance state when EN is off. Put a 10kΩ resistor between
MOSFET gate and source or GND to prevent electric accumulation of gate charge.
10.5V internal LDO output from VIN. Do not leave open, bypass with 1μF ceramic
capacitor.
Power supply input pin. A 100nF ceramic capacitor is recommended to be placed close
to VIN and GND pin.
External compensation pin. Connect RC network from this pin to GND to compensate
the control loop.
Output voltage feedback pin. The output voltage reference is 1.2V.
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EN
Pin
Number
1
Pin Name
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(SOP8)
Top Mark: FEMxyz (Device code:FEM, x=year code, y=week code, z= lot number code)
AN_SA22300 Rev. 0.9
© 2023 Silergy Corp.
Silergy Corp. Confidential- Prepared for Customer Use Only
4
All Rights Reserved.
SA22300
Absolute Maximum Ratings (Note 1)
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VIN, EN----------------------------------------------------------------------------------------------------------------- -0.3V to 40V
FB, ISEN, COMP------------------------------------------------------------------------------------------------------ -0.3V to 6V
GATE, VCC ----------------------------------------------------------------------------------------------------------- -0.3V to 13V
Power dissipation @TA = 25℃ -------------------------------------------------------------------------------------------- 1.26W
Package Thermal Resistance (Note 2)
θ JA ---------------------------------------------------------------------------------------------------------------------- 98.5°C/W
θ JB ------------------------------------------------------------------------------------------------------------------------- 58°C/W
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ΨJT ------------------------------------------------------------------------------------------------------------------------- 10°C/W
Junction Temperature Range ------------------------------------------------------------------------------------- -40°C to 150°C
Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------------ 260°C
Storage Temperature Range -------------------------------------------------------------------------------------- -65°C to 150°C
ESD Susceptibility (Note3)
HBM (Human Body Mode) --------------------------------------------------------------------------------------------------- 2000V
CDM (Charge Device Mode)All pins------------------------------------------------------------------------------------------500V
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Recommended Operating Conditions (Note 3)
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Supply Voltage VIN -------------------------------------------------------------------------------------------------- 3.45V to 36V
EN --------------------------------------------------------------------------------------------------------------------------- 0V to 36V
Ambient Temperature Range ------------------------------------------------------------------------------------- -40°C to 125°C
AN_SA22300 Rev. 0.9
© 2023 Silergy Corp.
Silergy Corp. Confidential- Prepared for Customer Use Only
5
All Rights Reserved.
SA22300
Electrical Characteristics
(3.45V≤VIN≤36V,-40°C≤TA≤125°C, unless otherwise specified)
Typ
Max
Unit
VUVLO_R
3.05
3.225
3.45
V
VUVLO_F
ISD
IOP
2.9
VEN=0V
VEN=3V, no switching
3.1
1.6
1.5
VVCC
VDROP
IVCC_LIMH
IVCC=10mA, VIN=12V
IVCC = 50mA
VCC drop 10%
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Error Amplifier
Transconductance of
Error Amplifier
COMP Sourcing Current
COMP Sinking Current
COMP High Clamp
COMP Low Clamp
COMP Low Threshold
Stop Switching
Slope Compensation
Current Sense
ISEN Pull up Current
Cycle by Cycle Current
Limit Threshold Voltage
AN_SA22300 Rev. 0.9
© 2023 Silergy Corp.
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Test Conditions
3.35
3
2.5
V
μA
mA
9.2
10.5
0.4
11.8
1
120
V
V
mA
2.85
3.0
3.15
V
2.75
2.9
3.05
V
1.425
1.380
0.03
0.5
1.5
1.45
0.05
1
1.575
1.520
0.08
μA
V
V
V
153
85
280
170
140
450
187
210
620
kHz
ns
ns
1.176
1.2
1.224
V
4.8
0.1
6
0.2
7.2
μA
ms
gm_ea
800
1200
1680
μS
ICOMP_SOURCE
ICOMP_SINK
VCOMP_HIGH
VCOMP_LOW
80
80
1.15
320
130
130
1.2
350
180
180
1.25
380
μA
μA
V
mV
VCOMP_BURST
370
400
430
mV
90
110
130
mV
IISEN_PU
10
30
50
μA
VCL
360
400
440
mV
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60
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VVCC_F
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IEN
VEN_H
VEN_L
VEN_hys
Vref
IFB_PU
Tss
VSLOPE
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Pr
VVCC_R
fSW
tON_MIN
tOFF_MIN
Fo
0.5
r
Symbol
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Parameter
VIN
VIN UVLO Rising
Threshold
UVLO Falling
Shutdown Current
Operating Current
VCC
VCC Output Voltage
Drop Out Voltage
VCC Current Limit
VCC Under Voltage
Reset Rising Threshold
VCC Under Voltage
Reset Falling Threshold
EN
EN Pull-Down Current
EN Logic ‘1’ Threshold
EN Logic ‘0’ Threshold
EN Hysteresis Voltage
Oscillator
Switching Frequency
Minimum On Time
Minimum Off Time
FB&SS
Output Feedback
Reference
FB Pull up Current
Soft-start Time
From 10%Vref to 90%Vref
D=100%
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SA22300
150
175
%
1.4
0.65
2.8
1.5
4.9
2.9
Ω
Ω
150
165
180
ºC
10
15
20
ºC
75
%VREF
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125
Fo
Percent of VCL
r
Over Current Protection
%VCL
Threshold Voltage
Gate Driver
Gate Driver HSFET Ron RHS_ON
Gate Driver LSFET Ron RLS_ON
Thermal Shutdown
Thermal Shutdown
TSD
Threshold
Thermal Shutdown
TSDHYS
Hysteresis
FB Short Circuit Protection
Short Circuit Threshold
Vscp
Voltage
60
67
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VFB as percent of Vref
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Note 1: Stresses beyond the “Absolute Maximum Ratings” may cause permanent damage to the device. These are
stress ratings only. Functional operation of the device at these or any other conditions beyond those indicated in the
operational sections of the specification is not implied. Exposure to absolute maximum rating conditions for
extended periods may affect device reliability.
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Note 2: θ JA is measured in the natural convection at TA = 25°C. Device mounted on an 8.5x8.5cm FR-4 substrate
PCB, 2oz copper, 2 layers.
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Note 3: Electrical characteristics are not guaranteed outside its operating conditions.
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Note 4: Guaranteed by design. Not tested in production.
AN_SA22300 Rev. 0.9
© 2023 Silergy Corp.
Silergy Corp. Confidential- Prepared for Customer Use Only
7
All Rights Reserved.
SA22300
Typical Performance Characteristics
(TA=25°C Boost Application)
Startup from VIN
(VIN =12V,VOUT=24V,IOUT=1A)
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Startup from VIN
(VIN =12V,VOUT=24V,IOUT=0A)
VIN 10V/div
VOUT 10V/div
VOUT 10V/div
VGA TE 10V/div
VGA TE 10V/div
VVCC 10V/div
VVCC 10V/div
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Fo
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VIN 10V/div
Time (4ms/div)
Pr
ep
Time (4ms/div)
Shutdown from VIN
Shutdown from VIN
(VIN =12V,VOUT=24V,IOUT=1A)
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(VIN =12V,VOUT=24V,IOUT=0A)
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VOUT 20V/div
VIN 10V/div
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VIN 10V/div
fi
VOUT 20V/div
on
VGA TE 10V/div
.C
VGA TE 10V/div
VVCC 10V/div
rp
VVCC 10V/div
Time (4ms/div)
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Time (10ms/div)
Startup from Enable
(VIN =12V,VOUT=24V,IOUT=1A)
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Startup from Enable
(VIN =12V,VOUT=24V,IOUT=0A)
VEN 10V/div
VEN 10V/div
VOUT 10V/div
VOUT 10V/div
VGA TE 10V/div
VGA TE 10V/div
VVCC 10V/div
VVCC 10V/div
Time (4ms/div)
AN_SA22300 Rev. 0.9
© 2023 Silergy Corp.
Time (4ms/div)
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All Rights Reserved.
SA22300
Shutdown from Enable
Shutdown from Enable
(VIN =12V,VOUT=24V,IOUT=0A)
(VIN =12V,VOUT=24V,IOUT=1A)
VEN 10V/div
VEN 10V/div
VOUT 20V/div
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VOUT 20V/div
VGA TE 10V/div
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r
VGA TE 10V/div
VVCC 10V/div
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VVCC 10V/div
Time (800us/div)
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Time (4ms/div)
Output Voltage Ripple
Output Voltage Ripple
(VIN =12V,VOUT=24V,IOUT=1A)
Pr
(VIN =12V,VOUT=24V,IOUT=0A)
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ΔVOUT 100mV/div
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VGA TE 10V/div
VGA TE 10V/div
IL
2A/div
.C
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IL 500mA/div
ΔVOUT 200mV/div
Time (10us/div)
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Time (10us/div)
Load Transient Response
(VIN =12V,VOUT=24V,IOUT=0~1A)
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Load Transient Response
(VIN =12V,VOUT=24V,IOUT=0.25A~1A)
ΔVOUT 500mV/div
Si
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ΔVOUT 500mV/div
IL 1A/div
IL 1A/div
Time (2ms/div)
AN_SA22300 Rev. 0.9
© 2023 Silergy Corp.
Time (2ms/div)
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9
All Rights Reserved.
SA22300
Output Over Current Protection
CBC current limit protection
(VIN =12V,VOUT=24V,IOUT=0.2A)
(VIN =12V,set VOUT=24V, V OUT force 22.8V)
VOUT 10V/div
VOUT 10V/div
VGA TE 10V/div
IL 2A/div
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VGA TE 10V/div
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Fo
IL 2A/div
Time (800us/div)
ep
ar
e
Time (10ms/div)
ISEN open Protection
VCC Short Circuit Protection
(VIN =12V,VOUT=24V,IOUT=0.2A)
Pr
(VIN =12V,VOUT=24V,IOUT=0.5A)
VVCC 10V/div
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1V/div
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VIS EN
nt
VOUT 10V/div
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VCOMP 500mV/div
VGA TE 10V/div
IL
2A/div
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VGA TE 10V/div
VOUT 20V/div
Time (2ms/div)
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Time (4ms/div)
FB open Protection
(VIN =12V,VOUT=24V,IOUT=0.5A)
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FB Short Protection
(VIN =12V,VOUT=24V,IOUT=0.2A)
VFB
1V/div
Si
VOUT 20V/div
VCOMP 500mV/div
VGA TE 10V/div
VGA TE
IL
1V/div
VOUT 10V/div
le
VCOMP
10V/div
2A/div
Time (10ms/div)
AN_SA22300 Rev. 0.9
© 2023 Silergy Corp.
Time (800us/div)
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All Rights Reserved.
SA22300
Efficiency VS Load Current
(IOUT=0~1A, L=47μH Boost)
100
95
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80
9VIN /24VOUT
65
12VIN /24VOUT
16VIN /24VOUT
60
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Fo
70
r
75
0.9
d
Efficiency (%)
90
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Pr
ep
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Load Current (A)
AN_SA22300 Rev. 0.9
© 2023 Silergy Corp.
Silergy Corp. Confidential- Prepared for Customer Use Only
11
All Rights Reserved.
SA22300
VIN
Detailed Description
L
VCC
CLK
The SA22300 is a non-synchronous controller for
Boost, Flyback and Sepic applications. The controller
integrates a gate driver with 1.5A current capability,
which can drive external MOSFET fast. Considering
the operation stability and ease of use, peak current
control strategy with built-in slope compensation is
adopted, where the switching current is sensed
through an external resistor to control the on-time.
The SA22300 has a fixed-frequency clock (170kHz)
to ensure constant operational frequency. During
light load operation, the controller will enter burst
mode to improve light-load efficiency.
R
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Q
CO
RO
RGS
Current
sense
ISEN
Acsa
RSEN
VRAMP
RFB1
FB
COMP
RZ
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gm
RFB2
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REF
CZ
Fo
r
Figure 5. Peak Current Mode Control Scheme
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Under Voltage Lockout
The SA22300 has input undervoltage lockout (UVLO)
protection. If VIN pin voltage drops below the
UVLO falling threshold, the device will shut down. It
will not restart until VIN pin voltage surpasses the
UVLO rising threshold when enabled.
EN
VIN UVLO_R
VIN
300μs
VIN UVLO_F
VCC UVLO_R
VCC
VREF
1ms
VFB
SS
VCOMP
COMP Low Clamp
GATE
.C
on
Current Mode Control
The SA22300 uses a fixed frequency peak current
mode control architecture. The peak current through
the external MOSFET is sensed through an external
sense resistor and fed into the ISEN pin. The sensed
current is added to the slope compensation ramp and
fed into the positive input of the PWM comparator.
The output voltage is also sensed through an external
feedback resistor divider network and fed into the
error amplifier negative input (feedback pin, FB).
The output of the error amplifier (COMP pin) is fed
into the negative input of the PWM comparator. At
the start of any switching cycle, the oscillator sets the
RS latch using the switch logic block. This forces a
high signal on the GATE pin and the external
MOSFET turns on. When the voltage on the positive
input of the PWM comparator exceeds the negative
input, the RS latch is reset and the external MOSFET
turns off.
D
GATE
Q
ia
The SA22300 has several built-in protection features
and is suitable for harsh automotive environment. On
the basis of peak current control, the SA22300
possesses fast and accurate cycle-by-cycle current
limit and over current protection (OCP). Once the
voltage drop of sense resistor exceeds OCP threshold,
the controller will enter hiccup mode to prevent
overheating of the external MOSEFT. Besides, the
SA22300 also has VCC short, FB short, ISEN pin
open and FB pin open protection. These protection
measures help to improve the system reliability and
make the controller robust for complicated
automotive environment.
S
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Figure 6. Start-up by VIN
VIN
EN
130μs
VCC UVLO_R
VCC
VREF
1ms
VFB
SS
VCOMP
COMP Low Clamp
GATE
Figure 7. Start-up by EN
The minimum supply voltage after start-up can be
further decreased by supplying the VIN pin from the
Boost converter output or an external power supply.
AN_SA22300 Rev. 0.9
© 2023 Silergy Corp.
Silergy Corp. Confidential- Prepared for Customer Use Only
12
All Rights Reserved.
SA22300
D
L
VSUPPLY
CIN
VOUT
VOUT
CO
RFB1
EN
RO
VIN UVLO_R
Short circuit
VIN
Short circuit
removal
300μs
VIN
Q
GATE
EN
RFB2
VCC UVLO_R
50%
VCC
RGS
VCC UVLO_F
VCC
current
ISEN
70% Current limit
RSEN
FB
15μs
SS
VCC
Cz
COMP Low Clamp
VCOMP COMP Low Clamp
GATE
Figure 8. Decrease the Minimum Operating
Voltage after Start-up
d
Figure 9. VCC Over Current Protection
Output Current Limit
The voltage drop of external current sense resistor
reflects the current information of the external
MOSFET and is fed to ISEN pin. On this basis,
SA22300 features cycle-by-cycle current limit and
over current protection.
cycle-by-cycle
current limit.
80ns
Hiccup mode auto
recover.
50%VVCC
80ns
-
-
-
-
FB Short
Circuit
67%VREF
400ns
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ISEN Open
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15μs
Turn off GATE,
reset COMP and SS.
Reduce current limit
by 30%.
100nA pull-up
current, FB voltage
increase and stop
switching.
30μA pull-up
current, trigger OCP.
Hiccup mode auto
recover, typical
30ms hiccup period.
.C
VVCC_F
on
150%VCL
If the voltage between ISEN and GND pin exceeds
cycle-by-cycle current limit value (VCL), the external
MOSFET will be turned off for the remainder of the
cycle. In cycle-by-cycle current limit state, the IC
still operates with the internal fixed frequency.
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80ns
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VCL=400mV
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Shutdown when
temperature>165℃
Restart when
temperature0.5. It is specially
designed to offer sufficient slope compensation.
COUT Selection
Output capacitor is used to smooth the voltage ripple.
The following equation is used to calculate the
minimum capacitance. Assuming the output voltage
ripple is 1%, we have:
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SA22300
COUT
IO D
1A 0.625
15F
VO f SW 1% 24V 170kHz
RZ
2RSEN f cCoVo
(1 Dmax ) g m _ eaVREF
2 50m 1.9kHz 67F 24V
(1 - 0.625) 1200S 1.2V
1.78k
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Considering the voltage drop during the load
transient, as well as the capacitance drop of ceramic
capacitor, we choose four 10μF ceramic capacitors. A
47μF electrolytic capacitor is also chosen in this
example.
We choose RZ=2kΩ in this example, and the fc
becomes 2.2kHz.
r
Loop Compensation
1) Calculate the RHP zero frequency fRHP_z and
crossover frequency fc.
Fo
When calculating RZ above, 50% capacitance
decrease of ceramic capacitor is considered.
3) Finally, we need to choose proper CZ.
If CZ=47nF, the compensated zero can be calculated
as:
d
(1 Dmax ) 2 RO
2L
24V
(1 0.625 ) 2
1A 11 .43kHz
2 47 H
ep
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f RHP _ Z
Pr
fZ
1
1
1.7kHz
2RZ CZ 2 2k 47nF
In this way, fz
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