®
RT6210
500mA, 80V, 350kHz Synchronous Step-Down Converter
General Description
The RT6210 is a 80V, 500mA, 350kHz, high-efficiency,
synchronous step-down DC-DC converter with an input-
voltage range of 5.2V to 80V and a programmable output-
voltage range of 0.8V to 72V. It features current-mode
control to simplify external compensation and to optimize
transient response with a wide range of inductors and output
capacitors. High efficiency can be achieved through
integrated N-MOSFETs, and pulse-skipping mode at light
loads. With EN pin, power-up sequence can be more
flexible and shutdown quiescent current can be reduced
to < 3μA.
The RT6210 features cycle-by-cycle current limit for over-
current protection against short-circuit outputs, and user-
programmable soft-start time to prevent inrush current
during startup. It also includes input under-voltage lockout,
output under-voltage, and thermal shutdown protection to
provide safe and smooth operation in all operating
conditions.
The RT6210 is available in the SOP-8 (Exposed pad)
package.
Features
0.8V Feedback Reference Voltage with
±
1.5%
Accuracy
Wide Input Voltage Range : 5.2V to 80V
Output Current : 500mA
Integrated N-MOSFETs
Current-Mode Control
Fixed Switching Frequency : 350kHz
Programmable Output Voltage : 0.8V to 72V
Low < 3μA Shutdown Quiescent Current
μ
Up to 92% Efficiency
Pulse-Skipping Mode for Light-Load Efficiency
Programmable Soft-Start Time
Cycle-by-Cycle Current Limit Protection
Input Under-Voltage Lockout, Output Under-Voltage
and Thermal Shutdown Protection
Applications
4-20mA Loop-Powered Sensors
OBD-II Port Power Supplies
Low-Power Standby or Bias Voltage Supplies
Industrial Process Control, Metering, and Security
Systems
High-Voltage LDO Replacement
Telecommunications Systems
Commercial Vehicle Power Supplies
General Purpose Wide Input Voltage Regulation
Simplified Application Circuit
Efficiency vs. Output Current
100
C
BOOT
90
80
V
IN
C
IN
VIN
RT6210
BOOT
SW
Efficiency (%)
70
60
50
40
30
20
10
0
0
0.1
0.2
0.3
0.4
0.5
L1
R1
V
OUT
Enable
EN
SS
COMP GND
C
C
C
SS
C
P
R
C
FB
C
FF
R2
C
OUT
V
IN
=
V
IN
=
V
IN
=
V
IN
=
V
IN
=
24V
36V
48V
60V
80V
V
OUT
= 12V
Output Current (A)
Copyright
©
2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS6210-00 May 2017
www.richtek.com
1
RT6210
Ordering Information
RT6210
Package Type
SP : SOP-8 (Exposed Pad-Option 2)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
½
Marking Information
RT6210GSP : Product Number
RT6210
GSPYMDNN
YMDNN : Date Code
Pin Configuration
(TOP VIEW)
BOOT
VIN
SW
GND
2
3
4
8
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.
SS
EN
COMP
FB
½
GND
9
7
6
5
SOP-8 (Exposed Pad)
Functional Pin Description
Pin No.
1
2
3
4, 9
(Exposed Pad)
Pin Name
BOOT
VIN
SW
GND
Pin Function
Bootstrap capacitor connection node for high-side gate driver. Connect a 0.1F
ceramic capacitor from BOOT to SW to power the internal gate driver.
Supply voltage input, 5.2V to 80V. Bypass VIN to GND with a large high-quality
capacitor.
Switch node for output inductor connection.
Power ground. The exposed pad must be connected to GND and well soldered
to the input and output capacitors and a large PCB copper area for maximum
power dissipation.
Feedback voltage input. Connect FB to the midpoint of the external feedback
resistor divider to sense the output voltage. The device regulates the FB voltage
at 0.8V (typical) Feedback Reference Voltage.
Compensation node for the compensation of the regulation control loop.
Connect a series RC network from COMP to GND. In some cases, another
capacitor from COMP to GND may be required.
Enable control input. A logic High (V
EN
> 1.35V) enables the device, and a logic
Low (V
EN
< 0.925V) shuts down the device, reducing the supply current to 3A
or below. Connect EN pin to VIN pin with a 100k pull-up resistor for automatic
startup.
Soft-start capacitor connection node. Connect an external capacitor from SS to
GND to set the soft-start time. Do not leave SS pin unconnected. A capacitor of
capacitance from 10nF to 100nF is recommended, which can set the soft-start
time from 1.33ms to 13.3ms, accordingly.
5
FB
6
COMP
7
EN
8
SS
Copyright
©
2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
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2
DS6210-00 May 2017
RT6210
Functional Block Diagram
VIN
EN
HV
Protection
-
1.2V
1µA
Thermal
Shutdown
UVLO
Internal
Regulator
+
Shutdown
Comparator
Current
Sense
BOOT
UVLO
BOOT
HS
SW
LS
HS Switch
Current
Comparator
0.4V
+
-
UV
Comparator
-
+ EA
+
Logic &
Clamp
Control
Gate Driver
with Dead
Time Control
FB
0.8V
6µA
LS Switch
Current
Comparator
Oscillator
Current
Sense
SS
COMP
Slope
Compensation
GND
Operation
The RT6210 is a synchronous step-down converter,
integrated with both high-side (HS) and low-side (LS)
MOSFETs to reduce external component count and a gate
driver with dead-time control logic to prevent shoot-through
condition from happening. The RT6210 also features
constant frequency and peak current-mode control with
slope compensation. During PWM operation, output
voltage is regulated down, and is sensed from the FB pin
to be compared with an internal 0.8V reference voltage
V
REF
. In normal operation, the high-side N-MOSFET is
turned on when an S-R latch is set by the rising edge of
an internal oscillator output as the PWM clock, and is
turned off when the S-R latch is reset by the output of a
(high-side) current comparator, which compares the high-
side sensed current signal with the current signal related
to the COMP voltage. While the high-side N-MOSFET is
turned off, the low-side N-MOSFET will be turned on. If
the output voltage is not established, the high-side power
switch will be turned on again and another cycle begins.
Pulse Skipping Operation
At very light-load condition, the RT6210 provides pulse
skipping technique to decrease switching loss for better
efficiency. When load current decreases, the FB voltage
V
FB
will increase slightly. With V
FB
1% higher than V
REF
,
the COMP voltage will be clamped at a minimum value
and the converter will enter into pulse skipping mode. When
the converter operates in pulse skipping mode, the internal
oscillator will be stopped, which makes the switching period
being extended. In pulse skipping mode, as the load
current decreases, V
FB
will be discharged more slowly,
which in turn will extend the switching period even more.
Error Amplifier
The RT6210 adopts a transconductance amplifier as the
error amplifier. The error amplifier of a typical 970μA/V
transconductance (gm) compares the feedback voltage
V
FB
with the lower one of the soft-start voltage or the
internal reference voltage V
REF
, 0.8V. As V
FB
drops due
to the load current increase, the output voltage of the error
Copyright
©
2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS6210-00 May 2017
www.richtek.com
3
RT6210
amplifier will go up so that the device will supply more
inductor current to match the load current. The frequency
compensation components, such as the series resistor
and capacitor, and an optional capacitor, are placed between
the COMP pin and ground.
Oscillator
The internal oscillator frequency is set to a typical 350kHz
as a fixed frequency for PWM operation.
Slope Compensation
In order to prevent sub-harmonic oscillations that may
occur over all specified load and line conditions when
operating at duty cycle higher than 50%, the RT6210
features an internal slope compensation, which adds a
compensating slope signal to the sensed current signal
to support applications with duty cycle up to 93%.
Internal Regulator
When the VIN is plugged in, the internal regulator will
generate a low voltage to drive internal control circuitry
and to supply the bootstrap power for the high-side gate
driver.
Chip Enable
The RT6210 provides an EN pin, as an external chip enable
control, to enable or disable the device. When VIN is higher
than the input under-voltage lockout
threshold (V
UVLO
) with
the EN voltage (V
EN
) higher than 1.3V, the converter will
be turned on. When V
EN
is lower than 0.875V, the converter
will enter into shutdown mode, during which the supply
current can be even reduced to 3μA or below.
External Soft-Start
The RT6210 provides external soft-start feature to reduce
input inrush current. The soft-start time can be programmed
by selecting the value of the capacitor C
SS
connected from
the SS pin to GND. An internal current source I
SS
(typically,
6μA) charges the external capacitor C
SS
to build a soft-
start ramp voltage. The feedback voltage V
FB
will be
compared with the soft-start ramp voltage during soft-start
time. For the RT6210, the external capacitor C
SS
is
required, and for soft-start control, the SS pin should never
be left unconnected, and it is not recommended to be
connected to an external voltage source. The soft-start
Copyright
©
2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
time depends on C
SS
capacitance; for example, a 0.1μF
capacitor for programming soft-start time will result in
18.333ms (typ.) soft-start time.
Output Under-Voltage Protection (UVP) with Hiccup
Mode
The RT6210 provides under-voltage protection with hiccup
mode. When the feedback voltage V
FB
drops below under-
voltage protection threshold V
TH-UVP
, half of the feedback
reference voltage V
REF
, the UVP function will be triggered
to turn off the high-side MOSFET immediately. The
converter will attempt auto-recovery soft-start after under-
voltage condition has occurred for a period of time. Once
the under-voltage condition is removed, the converter will
resume switching and be back to normal operation.
Current Limit Protection
The RT6210 provides cycle-by-cycle current limit
protection against over-load or short-circuited condition.
When the peak inductor current reaches the current limit,
the high-side MOSFET will be turned off immediately with
no violating minimum on-time t
ON_MIN
requirement to
prevent the device from operating in an over-current
condition.
Thermal Shutdown
The RT6210 provides over-temperature protection (OTP)
function to prevent the chip from damaging due to over-
heating. The over-temperature protection function will shut
down the switching operation when the junction
temperature exceeds 165°C. Once the over-temperature
condition is removed, the converter will resume switching
and be back to normal operation.
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4
DS6210-00 May 2017
RT6210
Absolute Maximum Ratings
(Note 1)
−0.3V
to 90V
−0.3V
to (V
IN
+ 0.3V)
−5V
to (V
IN
+ 4V)
−0.3V
to 90V
−0.3V
to 6V
−0.3V
to 6V
VIN (Note 5) -----------------------------------------------------------------------------------------------------------
SW
DC -----------------------------------------------------------------------------------------------------------------------
<200ns -----------------------------------------------------------------------------------------------------------------
EN Pin ------------------------------------------------------------------------------------------------------------------
BOOT to SW, V
BOOT
−
V
SW
---------------------------------------------------------------------------------------
Other Pins -------------------------------------------------------------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
SOP-8 (Exposed Pad) --------------------------------------------------------------------------------------------- 3.44W
Package Thermal Resistance (Note 2)
SOP-8 (Exposed Pad),
θ
JA
--------------------------------------------------------------------------------------- 29°C/W
SOP-8 (Exposed Pad),
θ
JC
--------------------------------------------------------------------------------------- 2°C/W
Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------- 260°C
Junction Temperature ----------------------------------------------------------------------------------------------- 150°C
Storage Temperature Range ---------------------------------------------------------------------------------------
−65°C
to 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Model) --------------------------------------------------------------------------------------- 2kV
Recommended Operating Conditions
(Note 4)
Supply Input Voltage ------------------------------------------------------------------------------------------------ 5.2V to 80V
Ambient Temperature Range --------------------------------------------------------------------------------------
−40°C
to 85°C
Junction Temperature Range --------------------------------------------------------------------------------------
−40°C
to 125°C
Electrical Characteristics
(V
IN
= 12V, T
A
= 25°C, unless otherwise specified)
Parameter
Supply Current
Shutdown Supply Current
Quiescent Supply Current
Reference
Feedback Reference Voltage
Enable and UVLO
Input Under-Voltage Lockout
Threshold
Input Under-Voltage Lockout
Hysteresis
EN Input Threshold
Voltage
Rising
Hysteresis
Symbol
Test Conditions
Min
Typ
Max
Unit
I
SHDN
I
Q
V
EN
= 0V
V
EN
= 0V, V
IN
= 80V
V
EN
= 3V, V
FB
= 0.9V
5V
V
IN
80V
--
--
--
0.5
20
0.6
3
--
--
A
mA
V
REF
0.788
0.8
0.812
V
V
UVLO
V
UVLO_HYS
V
TH_EN
V
TH_EN_HYS
V
IN
rising
4
200
1.1
4.6
350
1.2
--
5.2
500
1.3
225
V
mV
V
mV
Falling
25
Copyright
©
2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS6210-00 May 2017
www.richtek.com
5
Embedded System
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