Toshiba TCK321G, TCK322G, TCK323 Application Note
TCK321G, TCK322G, and TCK323 Load Switch ICs for 2-to-1 Power Multiplexing
1
© 2021
Application Note
TCK321G, TCK322G, and TCK323
Load Switch ICs for 2-to-1 Power Multiplexing
Application Note
Outline:
This application note describes the TCK321G, TCK322G, and TCK323 two-input, one-output load switch
ICs incorporating a multiplexer for selecting between two input power lines.
The power multiplexing function of load switch ICs is ideal for the power management of battery chargers
for mobile devices (e.g., smartphones and tablets) having two charging ports.
Toshiba Electronic Devices & Storage Corporation
2021-02-02
TCK321G, TCK322G, and TCK323 Load Switch ICs for 2-to-1 Power Multiplexing
2
© 2021
Application Note
Table of Contents
Outline: ............................................................................................................................................... 1
Table of Contents ................................................................................................................................ 2
1. Introduction ..................................................................................................................................... 6
2. Application examples for the TCK32*G ........................................................................................... 6
3. Differences among the TCK321G, TCK322G, and TCK323G ......................................................... 7
4. Block diagram of the TCK32*G and descriptions of internal blocks ................................................. 8
4.1. Overvoltage lockout (OVLO) circuit [Figure 4.1(1)] ............................................................................. 8
4.2. Undervoltage lockout (UVLO) circuit [Figure 4.1(2)] ......................................................................... 10
4.3. Inrush current limiting (slew rate control) circuit [Figure 4.1(3)] ........................................................ 11
4.4. Charge pump circuit [Figure 4.1(4)] ................................................................................................... 12
4.5. Reverse current blocking circuit [Figure 4.1(5)] ................................................................................. 12
4.6. Thermal shutdown (TSD) circuit [Figure 4.1(6)] ................................................................................ 13
4.7. FLAG output circuit [Figure 4.1(7)] .................................................................................................... 14
4.8. Other circuit in the TCK32*G ............................................................................................................. 15
4.8.1. Break-before-make circuit ...................................................................................................................15
5. Internal circuits at the control input pins ........................................................................................ 15
5.1. Internal circuit at the CNT pin ............................................................................................................ 15
5.2. Internal circuit at the V
pin ............................................................................................................. 15
SEL
6. Control modes of the TCK32*G ..................................................................................................... 16
6.1. Off Mode ............................................................................................................................................ 16
6.2. Auto Selection mode .......................................................................................................................... 16
6.2.1. Timing diagram of the TCK321G and TCK322G in Auto Selection mode ..........................................17
6.2.2. Timing chart of the TCK323G in Auto Selection mode .......................................................................20
6.3. Manual Selection mode ..................................................................................................................... 22
7. Definitions of the AC characteristics of the TCK32*G .................................................................... 26
7.1. Hold time (t
7.2. V
selection delay time (t
IN
7.3. Break-before-make time (t
7.4. V
7.5. V
OVP off-time (t
OUT
off-time (CNT) (t
OUT
) .................................................................................................................................... 26
HD
) ............................................................................................................ 26
SEL
)........................................................................................................... 26
BBM
) .................................................................................................................... 27
OVP
) .................................................................................................................. 27
OFF
7.6. V
rise time (tr) and V
OUT
fall time (tf) ............................................................................................. 28
OUT
8. Calculating the power dissipation and junction temperature of an IC ............................................. 28
9. Usage considerations .................................................................................................................... 30
9.1. External capacitors ............................................................................................................................ 30
9.2. Board assembly ................................................................................................................................. 30
9.3. Protection circuits ............................................................................................................................... 30
9.4. Power dissipation ............................................................................................................................... 30
10. Conclusion .................................................................................................................................. 31
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TCK321G, TCK322G, and TCK323 Load Switch ICs for 2-to-1 Power Multiplexing
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Application Note
RESTRICTIONS ON PRODUCT USE .............................................................................................. 32
2021-02-02
Toshiba Electronic Devices & Storage Corporation
TCK321G, TCK322G, and TCK323 Load Switch ICs for 2-to-1 Power Multiplexing
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Application Note
List of Figures
Figure 2.1 Example of a multiplexer circuit using the TCK321G, TCK322G and TCK323G ......................... 6
Figure 2.2 Example of a multiplexer circuit composed of discrete devices ................................................... 7
Figure 2.3 Example of a multiplexer circuit composed of non-multiplexing load switch ICs ......................... 7
Figure 4.1 Block diagram of the TCK32*G ..................................................................................................... 8
Figure 4.2 Overvoltage lockout operation ...................................................................................................... 9
Figure 4.3 Example of operations when entering and exiting OVLO mode .................................................. 9
Figure 4.4 Undervoltage lockout operation .................................................................................................. 11
Figure 4.5 Output current waveform when inrush current is limited ............................................................ 12
Figure 4.6 Reverse blocking current (I
)-vs-output voltage (V
RB
) curve of the TCK32*G ........................ 12
OUT
Figure 4.7 Reverse current blocking operation during switching between two power supplies .................. 13
Figure 4.8 Thermal shutdown operation ...................................................................................................... 14
Figure 4.9 Equivalent circuit for the FLAG output ........................................................................................ 14
Figure 4.10 Break-before-make operation ................................................................................................... 15
Figure 5.1 Internal circuit at the CNT pin ..................................................................................................... 15
Figure 5.2 Internal circuit at the V
pin ...................................................................................................... 16
SEL
Figure 6.1 Control modes of the TCK32*G .................................................................................................. 16
Figure 6.2 Timing diagram of the TCK321G and TCK322G in Auto Selection mode ................................. 18
Figure 6.3 Timing diagram of the TCK323G in Auto Selection mode .......................................................... 21
Figure 6.4 Timing diagram of the TCK321G, TCK322G, and TCK323G in Manual Selection mode .......... 24
Figure 7.1 Example of a chattering waveform.............................................................................................. 26
Figure 7.2 Hold time ..................................................................................................................................... 26
Figure 7.3 Definitions of V
Figure 7.4 Definition of V
Figure 7.5 Definition of V
Figure 7.6 Definitions of V
selection time (t
IN
OVP off-time (t
OUT
off-time (t
OUT
rise time (tr) and V
OUT
OFF
) and break-before-make time (t
SEL
) ......................................................................................... 27
OVP
) ................................. 27
BBM
) .................................................................................................. 27
fall time (tf)................................................................. 28
OUT
Figure 8.1 Power dissipation (P
) vs. ambient temperature (Ta) ................................................................. 29
D
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TCK321G, TCK322G, and TCK323 Load Switch ICs for 2-to-1 Power Multiplexing
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Application Note
List of Tables
Table 3.1 Functions available with and differences among the TCK321G, TCK322G, and TCK323G ........ 7
Table 4.1 Comparison of overvoltage lockout thresholds among the TCK32*G ......................................... 10
Table 4.2 Undervoltage lockout thresholds of the TCK32*G ....................................................................... 11
Table 6.1 Operations of the TCK321G, TCK322G, and TCK323G in Off mode ......................................... 16
Table 6.2 Operations of the TCK321G, TCK322G, and TCK323G in Auto Selection mode ....................... 17
Table 6.3 Operations of the TCK321G and TCK322G in Auto Selection mode .......................................... 19
Table 6.4 Operations of the TCK323G in Auto Selection mode .................................................................. 22
Table 6.5 Operations of the TCK321G, TCK322G, and TCK323G in Manual Selection mode .................. 23
Table 6.6 Operations of the TCK321G, TCK322G, and TCK323G in Manual Selection mode .................. 25
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TCK321G, TCK322G, and TCK323 Load Switch ICs for 2-to-1 Power Multiplexing
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Application Note
1. Introduction
A load switch IC for 2-to-1 power multiplexing (power multiplexer IC) selects between two input
power lines and forwards the selected input to the subsequent IC or circuitry. The TCK321G,
TCK322G, and TCK323G (hereinafter collectively referred to as the TCK32*G) are ideal for the power
management of high-current, high-voltage battery charging applications for smartphones, tablets,
and other mobile devices having two charging ports. The TCK32*G series incorporates inrush current
limiting (slew rate control), thermal shutdown, overvoltage lockout, undervoltage lockout, reverse
current blocking, and flag output functions. Fabricated with a high-voltage CMOS process, the
TCK32*G 2-to-1 power multiplexer ICs support an input voltage up to 36 V. In addition, the TCK32*G
series provides not only Manual Selection mode in which an input power line is selected via an
external control signal but also Auto Selection mode in which an input power line is automatically
selected according to input voltages. The Auto Selection mode eliminates the need for an external
control signal, enabling the TCK32*G series to operate on its own.
This application note describes the functions and operations of the TCK32*G. For details of the
protection functions and other features available with the TCK32*G, see their datasheets.
To download the datasheet for the TCK321G →
To download the datasheet for the TCK322G →
To download the datasheet for the TCK323G →
2. Application examples for the TCK32*G
Figure 2.1 shows an example of a multiplexer circuit using the TCK32*G, which selects between
two input power lines and forwards the selected input to the output. This circuit supplies either V
from a USB connector or V
from a wireless charger to a mobile device.
INB
INA
Figure 2.1 Example of a multiplexer circuit using the TCK321G, TCK322G and
TCK323G
2021-02-02
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TCK321G, TCK322G, and TCK323 Load Switch ICs for 2-to-1 Power Multiplexing
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Functions available with and differences among the TCK321G, TCK322G, and
(OVLO)
Thermal
Overcurrent
switch-off)
Application Note
Figure 2.2 and Figure 2.3 show equivalent multiplexer circuits using discrete devices and
non-multiplexing load switch ICs, respectively. The use of the TCK32*G, a dedicated power
multiplexer IC, helps reduce parts counts and therefore the system size.
Figure 2.2 Example of a multiplexer circuit
composed of discrete devices
Figure 2.3 Example of a multiplexer
circuit composed of non-multiplexing
load switch ICs
3. Differences among the TCK321G, TCK322G, and TCK323G
The TCK321G, TCK322G, and TCK323G differ in the input power line whose state is indicated by
the FLAG output in Auto Selection mode (V
V
state in the case of the TCK323G) as well as in overvoltage lockout threshold.
INB
Table 3.1
Overvoltage
Part
number
TCK321G 12.0 V
lockout
V
INA
(typ.)
V
12.0 V
(typ.)
Undervoltage
lockout (UVLO)
V
INB
2.6 V
(typ.)
INA
V
2.6 V
(typ.)
INB
state in the case of the TCK321G and TCK322G and
INA
TCK323G
Reverse
Inrush
current
limiting
shutdow
n (TSD)
–
protection
Break-be
fore-ma
ke
current
blocking
(at
FLAG output
(in Auto Selection
mode)
(V
Q
1
INA
) state
TCK322G 15.0 V
(typ.)
TCK323G 15.0 V
(typ.)
15.0 V
(typ.)
15.0 V
(typ.)
2.6 V
(typ.)
2.6 V
(typ.)
2.6 V
(typ.)
2.6 V
(typ.)
–
–
(V
1
2
(V
) state
INA
) state
INB
Q
Q
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Application Note
4. Block diagram of the TCK32*G and descriptions of internal blocks
Figure 4.1 Block diagram of the TCK32*G
4.1. Overvoltage lockout (OVLO) circuit [Figure 4.1(1)]
When either V
V
outputs to protect the ICs and circuits connected to them. The OVLO circuit is tripped when V
OUT
or V
exceeds the overvoltage lockout rising threshold (V
INB
below the overvoltage lockout falling threshold (V
The OVLO circuit compares V
(V
) as shown in Figure 4.2. When V
REF
comparator output is toggled, then turning off the V
MOSFET for reference voltage (comparator input) selection turns on, then the reference voltage
switches to V
OVDET_r
toggled again, turning the V
INA
or V
exceeds a threshold, the overvoltage lockout (OVLO) circuit turns off the
INB
. When V
or V
INA
or V
INA
outputs back on.
OUT
with a voltage derived by dividing the reference voltage
INB
or V
INA
drops below V
INB
). Then, when V
OVL_RI
OLV_FA
exceeds the divided reference voltage (V
INB
), the V
outputs. At the same time, the N-channel
OUT
OVDET_r
output turns back on automatically.
OUT
again, the comparator output is
INA
or V
drops
INB
OVDET
), the
INA
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TCK321G, TCK322G, and TCK323 Load Switch ICs for 2-to-1 Power Multiplexing
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IN
OUT
Entering OVLO mode
Exiting OVLO mode
Application Note
Figure 4.2 Overvoltage lockout operation
When recovering from overvoltage lockout, the OVLO circuit allows a hold time of 15 ms typical to
prevent a false output due to input chattering as shown in 4.3.
Test conditions: C
= 1 μF, C
= 1 μF, RL = 50 Ω
15 ms
Figure 4.3 Example of operations when entering and exiting OVLO mode
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Ta = 25°C
Ta = 40 to 85°C
Min
Typ.
Max
Min
Max
threshold
threshold
threshold
threshold
threshold
threshold
Application Note
Table 4.1 Comparison of overvoltage lockout thresholds among the TCK32*G
Part
number
TCK321G
TCK322G
TCK323G
Characteristics Symbol Test Condition
Overvoltage lockout
V
(OVLO) rising
Overvoltage lockout
(OVLO) falling
Overvoltage lockout
(OVLO) rising
Overvoltage lockout
(OVLO) falling
Overvoltage lockout
(OVLO) rising
Overvoltage lockout
(OVLO) falling
– – 12.0 – 10.5 13.5 V
OVL_RI
V
V
V
V
V
– –
OVL_FA
– – 15.0 – 13.4 16.6 V
OVL_RI
– –
OVL_FA
– – 15.0 – 13.4 16.6 V
OVL_RI
– –
OVL_FA
V
OVL_RI
- 0.5
V
OVL_RI
- 0.5
V
OVL_RI
- 0.5
4.2. Undervoltage lockout (UVLO) circuit [Figure 4.1(2)]
– – V
–
– – V
–
– – V
–
Unit
When either V
connected to the V
prevent system malfunction. The UVLO circuit is tripped when either V
undervoltage lockout falling threshold voltage (V
or V
compares V
rises back above V
INB
INA
Figure 4.4. When V
output is toggled, then the V
INA
or V
or V
outputs, the undervoltage lockout (UVLO) circuit turns off the V
OUT
with a voltage derived by dividing the reference voltage (V
INB
or V
INA
drops below the minimum operating voltage of the ICs or circuits
INB
or V
INA
UVL_FA
, the V
UVL_RI
drops below the divided reference voltage (V
INB
outputs turn off. At the same time, the N-channel MOSFET for
OUT
outputs turn back on automatically. The UVLO circuit
OUT
). The UVLO circuit has hysteresis. When V
UVDET
reference voltage selection turns off, then the reference voltage switches to V
V
rises back above V
INB
UVDET_r
, the comparator is toggled again, turning the V
outputs to
OUT
drops below the
INB
) as shown in
REF
), the comparator
UVDET_r
OUT
. When V
outputs back on.
INA
INA
or
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