TSM108IDT ,AUTOMOTIVE SWITCH MODE VOLTAGE & CURRENT CONTROLLERTSM108AUTOMOTIVE SWITCH MODEVOLTAGE AND CURRENT CONTROLLER■ CURRENT MEASUREMENT ON OUTPUT APPLICATI ..
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TSM109AIDT ,DUAL COMPARATOR AND VOLTAGE REFERENCEELECTRICAL CHARACTERISTICSCOMPARATOR (independent comparator)-+V = +5V, V = GND, T = +25°C (unless ..
TSM109ID ,DUAL COMPARATOR AND VOLTAGE REFERENCEABSOLUTE MAXIMUM RATINGS Symbol Parameter Value UnitV Supply voltage 36 VCCVDifferential Input ..
TSM109IDT ,DUAL COMPARATOR AND VOLTAGE REFERENCEELECTRICAL CHARACTERISTICS+ -V = 5V, V = 0V, T = 25°C (unless otherwise specified) CC CC ambSymb ..
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UC2827N-2 ,1features of the UC3827 include bidirectional synchronization capability, user programmableoverlap t ..
UC282T-2 ,1maximum ratings” may cause permanent damage to the device. These are stress ratings only, andfuncti ..
UC282T-3 ,1maximum ratings” may cause permanent damage to the device. These are stress ratings only, andfuncti ..
UC282T-ADJ ,1maximum ratings” may cause permanent damage to the device. These are stress ratings only, andfuncti ..
UC282TD-1 ,1maximum ratings” may cause permanent damage to the device. These are stress ratings only, andfuncti ..
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TSM108ID-TSM108IDT
AUTOMOTIVE SWITCH MODE VOLTAGE & CURRENT CONTROLLER
CURRENT MEASUREMENT ON OUTPUT POSITIVE LINE CONSTANT VOLTAGE MODE CONTROL CONSTANT CURRENT MODE CONTROL PRECISION VOLTAGE AND CURRENT
CONTROL LOOPS ADJUSTABLE SWITCHING FREQUENCY ADJUSTABLE OVER VOLTAGE LOCKOUT ADJUSTABLE UNDER VOLTAGE LOCKOUT STANDBY MODE (LOW QUIESCENT
CURRENT) SUSTAINS 60V MINIMAL EXTERNAL COMPONENTS
COUNT DRIVING ABILITY FOR EITHER P-MOSFET
OR PNP TRANSISTORS
DESCRIPTIONTSM108 is a P-channel MOSFET controller which
ensures constant voltage and constant current in
Switching Mode Power Supply (step down) like in
automotive battery charging applications.
TSM108 can easily be configured for very wide
voltage and current needs.
TSM108 is built in rugged BCD technology and
includes a PWM generator, Voltage and Current
control loops, a precision Voltage Reference, and
a P-Mosfet Gate Drive output. TSM108 can
sustain 60V on Vcc, and therefore meet the
standard Load Dump requirements in the
Automotive field.
TSM108 includes security functions which lock the
PMosfet in OFF state: OVLO (Over Voltage
Lockout) and UVLO (Under Voltage Lockout). The
P-Mosfet Gate is also protected from over voltage
drive thanks to a 12V clamping protection circuit.
TSM108 includes a standby feature which allows
very low quiescent current when activated, as well
as safe P-Mosfet Off state.
TSM108 is suitable for car environment
accessories, as well as numerous other DC/DC
step down regulation.
APPLICATION DIAGRAM
ORDER CODE D = Small Outline Package (SO) - also available in Tape & Reel (DT)
PIN CONNECTIONS (top view)
TSM108AUTOMOTIVE SWITCH MODE
VOLTAGE AND CURRENT CONTROLLER
TSM108
PIN DESCRIPTION
ABSOLUTE MAXIMUM RATINGS
OPERATING CONDITIONS
TSM108
ELECTRICAL CHARACTERISTICSTamb = 25°C, VCC = 12V (unless otherwise specified) Vref parameter indicates global precision of the voltage control loop. Control Gain : Av = 95dB ; Input Resistance : Rin = infinite ; Output Resistance : Rout = 700MΩ ; Output Source/Sink Current :
Iso, Isi = 150μA ; Recommended values for the compensation network are : 22nF & 22kΩ in series between output and ground. Vsense parameter indicated global precision of the current control loop. Control Gain : Av = 105dB ; Input Resistance : Rin =380kΩ ; Output Resistance : Rout = 105MΩ ; Output Source/Sink Current :
Iso, Isi = 150μA ; Recommended values for the compensation network are : 22nF & 22kΩ in series between output and ground. A current foldback function is implemented thanks to a systematic -6mV negative offset on the current amplifier inputs which
protects the battery from over charging current under low battery voltage conditions, or output short circuit conditions. The Gate Drive output stage has been optimized for PMosfets with input capacitance equal to Cload. A bigger Mosfet (with input
capacitance higher than Cload) can be used with TSM108, but the gate drive performances will be reduced (in particular when
reaching the Dmax. PWM mode). The given limits comprise the hysteresis (UVhyst). It is possible to modify the UVLO and OVLO limits by adding a resistor (to ground or to VCC) on the pins UV and OV.
The internal values of the resistor should be taken into account
TSM108
DETAILED INTERNAL SCHEMATIC
TSM108
OSCILLATOR FREQUENCY VERSUS TIMING CAPACITOR
TSM108 AS A STAND ALONE DC/DC CONVERTER FOR CIGARETTE LIGHTER ACCESSORIES
Description of a DC/DC step down battery
charging application
1. Voltage and Current ControllerTSM108 is designed to drive a P-Channel
MOSFET transistor in Switch Mode Step Down
Converter applications. Its two integrated
operational amplifiers ensure accurate Voltage
and Current Regulation.
The Voltage Control dedicated operational
amplifier acts as an error amplifier and compares part of the output voltage (external resistor
bridge) to an integrated highly precise voltage
reference (Vref).
The Current Control dedicated operational
amplifier acts as an error amplifier and compares
the drop voltage through the sense resistor to an
integrated low value voltage reference (Vs).
These two amplified errors are ORed through
diodes, and the resulting signal (“max of”) is a
reference for the PWM generator to set the
switching duty cycle of the P-Channel MOSFET
transistor.
The PWM generator comprises an oscillator (saw
tooth) and a comparator which gives a variable
duty cycle from 0 to 95%. This PWM signal is the
direct command of the output Push Pull stage to
drive the Gate of the P-Channel MOSFET.
Thanks to this architecture, the TSM108 is ideal to
be used from a DC power supply to control the
charging Voltage and Current of a battery in
applications such as Automotive accessories for
Portable Phone charging and power supplies.
2. Voltage ControlThe Voltage Control loop is to be set thanks to an
external resistor bridge connected between the
output positive line and the Ground reference. The
middle point is to be connected to the Vctrl pin of
TSM108, and, if R1 is the upper resistor, and R2,
the lower resistor of the bridge, the values of R1
and R2 should follow: eq1: Vref = Vout x R2 / (R1 + R2)
When under Constant Voltage Control mode, the
output voltage is fixed thanks to the R1/R2 resistor
bridge.
The total value of R1 + R2 resistor bridge will
determine the necessary bleeding current to keep
the Voltage Control loop effective, even under “no
load” conditions.
The voltage compensation loop is directly
accessible from the pins Vcomp and Vref
(negative input of the Voltage Control dedicated
operational amplifier). The compensation network
is highly dependant of the conditions of use of the
TSM108 (switching frequency, external
components (R, L, C), MOSFET, output
capacitor...).
3. Current ControlThe Current control loop is to be set thanks to the
Sense resistor which is to be placed in series on
the output positive line. The output side of the
Sense resistor should be connected to the Ictrl pin
of TSM108, and the common point between
Rsense and the filtering self L should be
connected to the Vs pin of TSM108. If Ilim is the
value of the charging current limit The value of
Rsense should verify: eq2: Vs = Rsense x Ilim
When under Constant Current Control mode, the
output current is fixed thanks to the Rsense
resistor (under output short circuit conditions,
please refer to this corresponding section).
The wattage calibration (W) of the sense resistor
should be chosen according to: eq2a: W > Rsense x Ilim2
The current compensation loop is directly
accessible from the pins Icomp and Ictrl (negative
input of the Current Control dedicated operational
amplifier.
The compensation network is highly dependant of
the conditions of use of the TSM108 (switching
frequency, external components (R, L, C),
MOSFET, output capacitor...).
4. PWM frequencyThe internal oscillator of TSM108 is a saw tooth
waveform that can be frequency adjusted.
In automotive accessory battery charging
applications, it is recommended to set the
switching frequency at a typical 100kHz in order to
PRINCIPLE OF OPERATION AND APPLICATION HINTS
TSM108
TSM108obtain the best compromise between electrical
noise, and size of the filtering self.
An external capacitor is to be connected between
ground and the Osc pin of TSM108 to set the
switching frequency.
The maximum duty cycle of the PWM function is
limited to 95% in order to ensure safe driving of
the MOSFET.
5. Gate DriveThe Gate Drive stage is directly commanded from
the PWM output signal. The Gate Drive stage is a
Push Pull Mosfet stage which bears different On
resistances in order to ensure a slower turn ON
than turn OFF of the P-Channel MOSFET. The
values of the output Gate Drive currents are given
by Isink (switch ON) and Isource (switch OFF).
The Gate Drive stage bears an integrated voltage
clamp which will prevent the P-Channel MOSFET
gate to be driven with voltages higher than 15V
(acting like a zener diode between Vcc and GD
(Gate Drive) pin.
6. Under Voltage Lock-Out, Over Voltage
Lock-OutThe UVLO and OVLO security functions aim at the
global application security.
When the Power supply decreases, there is the
inherent risk to drive the P-Channel MOSFET with
insufficient Gate voltage, and therefore to lead the
MOSFET to linear operation, and to its
destruction.
The UVLO is an input power supply voltage
detection which imposes a complete switch OFF
of the P-Channel MOSFET as soon as the Power
Supply decreases below UV. To avoid unwanted
oscillation of the MOSFET, a fixed hysteresis
margin is integrated (UVhyst).
UVLO is internally programmed to ensure 8V min
and 9V max, but the middle point of the integrated
resistor bridge is accessible and the value of the
UVLO is therefore adjustable by adding an
external resistor to modify the bridge ratio. The
resistor typical values of the bridge are given
(Ruvh, Ruvl).
When the Power supply increases, there is the
inherent risk to dissipate too much conduction
energy through the P-Channel MOSFET, and
therefore to lead to its destruction.
The OVLO is an input power supply voltage
detection which imposes a complete switch OFF
of the P-Channel MOSFET as soon as the Power
Supply increases above OV. To avoid unwanted
oscillation of the MOSFET, a fixed hysteresis
margin is integrated (OVhyst).
OVLO is internally programmed to ensure 32V
min. and 33V max., but the middle point of the
integrated resistor bridge is accessible and the
value of the OVLO is therefore adjustable by
adding an external resistor to modify the bridge
ratio.
The resistor typical values of the bridge are given
(Rovh, Rovl).
Examples:Let’s suppose that the internally set value of the
UVLO and / or OVLO level should be modified in a
specific application, or under specific
requirements.
6.1. UVLO decrease:If the UVLO level needs to be lowered (UV1), an
additional resistor (Ruvh1) must be connected
between UV and Vcc following the equation: UV = Vref (Ruvh/Ruvl +1) UV1 = Vref ((Ruvh//Ruvh1)/Ruvl +1) (i)
where Ruvh//Ruvh1 means that Ruvh1 is in
parallel to Ruvh
Solving i. we obtain: Ruvh1 = Ruvl x Ruvh (UV1 - Vref) / (Vref x
Ruvh - Ruvl (UV1 - Vref))
As an example, if UV1 needs to be set to 6V,
Ruvh1 = 256kΩ
6.2. UVLO increase:If the UVLO level needs to be increased (UV2), an
additional resistor (Ruvl2) must be connected
between UV and Gnd following the equation. UV = Vref (Ruvh/Ruvl +1) UV1 = Vref (Ruvh/(Ruvl//Ruvl2) +1) (ii)
where Ruvl//Ruvl2 means that Ruvl2 is in parallel
to Ruvl
Solving ii. we obtain: Ruvl2 = Vref x Ruvh Ruvl / (UV2 x Ruvl -
Vref x (Ruvh + Ruvl))
As an example, if UV2 needs to be set to 12V,
Ruvl2 = 132kΩ
6.3. OVLO decrease:If the OVLO level needs to be lowered (OV1), an
additional resistor (Rovh1) must be connected
between OV and Vcc following the equation: OV = Vref (Rovh/Rovl +1) OV1 = Vref ((Rovh//Rovh1)/Rovl +1) (iii)
where Rovh//Rovh1 means that Rovh1 is in
parallel to Rovh
Solving iii. we obtain: Rovh1 = Rovl x Rovh (OV1 - Vref) / (Vref x
Rovh - Rovl (OV1 - Vref))
As an example, if OV1 needs to be set to 25V,
Rovh1 = 867kΩ
