TSM108
VOLTAGE AND CURRENT STEPDOWN PWM CONTROLLER
■
OUTPUT HIGH SIDE CURRENT SENSING
■
PRECISE CC/CV REGULATION
■
ADJUSTABLE SWITCHING FREQUENCY
■
ADJUSTABLE OVP/UVP UVLO
THRESHOLDS
APPLICATION DIAGRAM
■
STANDBY MODE FEATURE
■
SUSTAINS 60V
■
MINIMAL EXTERNAL COMPONENTS
COUNT
■
DRIVES EXTERNAL P-CHANNEL MOSFET
OR PNP BIPOLAR TRANSISTORS
DESCRIPTION
TSM108 is a step-down PWM controller designed
to drive an external P-channel MOSFET, provid-
ing constant voltage and constant current regula-
tions in battery charger applications.
TSM108 can easily be configured for very wide
voltage and current needs.
It has been realized in rugged BCD technology
and includes a PWM generator, Voltage and Cur-
rent control loops, a precise Voltage Reference,
and a Gate Driver. The device can sustain 60V on
Vcc, and therefore meet the standard Load Dump
requirements of the 12V cars battery.
On boards there are other security functions which
lock the external power in OFF state: OVLO (Over
Voltage Lockout) and UVLO (Under Voltage Lock-
out). The mosfet gate is also protected from over
voltage drive thanks to a 12V clamping protection
circuit.
Moreover, a standby feature allows very low qui-
escent current when activated, but keeping safe
the external power element when Off.
The IC is suitable for 12V car accessories, as well
as other DC/DC step down converters.
D
SO14
(Plastic Micropackage)
ORDER CODE
Package
Part Number
TSM108I
Temperature Range
D
-40°, +125°C
•
D = Small Outline Package (SO) - also available in Tape & Reel (DT)
PIN CONNECTIONS
(top view)
VCC
!STBY
GND
UV
OV
G
OSC
1
2
3
4
5
6
7
14
13
12
11
10
9
8
GD
VS
ICTRL
VCTRL
VREF
ICOMP
VCOMP
March 2006
1/13
TSM108
PIN DESCRIPTION
Name
VCC
!STBY
GND
UV
OV
G
OSC
VCOMP
ICOMP
VREF
VCTRL
ICTRL
VS
GD
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Description
Supply voltage of both the signal part and the gate drive
Standby Command; when Low, the device goes in standby
Ground. Current return for both the gate drive and quiescent currents
Programmable Under Voltage Lockout. Preset value is 8V min
Programmable Over Voltage Lockout. Preset value is 33V max
Internally Connected to Ground
Oscillator pin to set operating frequency via external capacitor
Error amplifier output of voltage loop
Error amplifier output of current loop
2,52V Voltage Reference
Error amplifier of voltage loop, non inverting
Error amplifier of current loop inverting input
Current sense Input
Totem pole gate driver for external P-channel MOSFET
ABSOLUTE MAXIMUM RATINGS
Symbol
V
CC
T
j
R
thja
T
stg
V
max
Parameter
Supply Voltage - Transient conditions (400ms max.)
Maximum Junction Temperature
Thermal Resistance Junction to Ambient (SO package)
Storage Temperature
Out Terminal Voltage (ICTRL, VS)
Value
60
150
130
-55 to +125
10
Unit
V
°C
°C/W
°C
V
OPERATING CONDITIONS
Symbol
V
CC
Supply Voltage
Out Terminal Voltage (ICTRL, VS)
Out Terminal Voltage (UV, OV, OSC)
Parameter
Value
UVLO to OVLO
0 to 9
0 to 6
Unit
V
V
V
V
ter1
V
ter2
2/13
TSM108
ELECTRICAL CHARACTERISTICS
T
amb
= 25°C, V
CC
+ 12V (unless otherwise specified)
Symbol
I
CC
I
stby
V
sh
Parameter
Current Consumption
Current Consumption in Standby Mode
Input Standby Voltage High Impedance
Internal Pull up resistor.
Stby pin should be left
open
2
Test Condition
Min.
Typ.
4
150
Max.
7
Unit
mA
µA
V
CURRENT CONSUMPTION
STANDBY
V
sl
F
OSC
V
ref
Input Standby Voltage Low
Frequency of the Oscilator
Voltage Control Reference
C
OSC
= 220pF
T
amb
= 25°C
-25°C < T
amb
< 85°C
T
amb
= 25°C
-25°C < T
amb
< 85°C
T
amb
= 25°C
-25°C < T
amb
< 85°C
T
amb
= 25°C
-25°C < T
amb
< 85°C
70
100
2.520
2.450
196
191
206
0.8
130
V
kHz
V
OSCILLATOR
VOLTAGE CONTROL
1) 2)
2.590
216
221
mV
CURRENT CONTROL
3) 4) 5)
V
sense
Current Control Reference Voltage
GATE DRIVE - P CHANNEL MOSFET DRIVE
I
sink
I
source
C
load
Sink Current - Switch ON
Source Current - Swith OFF
Input Capacitance of the PMOSFET
6)
Maximum Duty Cycle of the PWM function
Under Voltage Lock Out
7)
UVLO Voltage Hysteresis - low to high
Upper Resistor of UVLO bridge
8)
Lower Resistor of UVLO bridge (see note 8)
Over Voltage Lock Out (see note 7)
OVLO Voltage Hysteresis - low to high
Upper Resistor of OVLO bridge (see note 8)
Lower Resistor of OVLO bridge (see note 8)
T
amb
= 25°C
T
amb
= 25°C
-25°C < T
amb
< 85°C
T
amb
= 25°C
T
amb
= 25°C
-25°C < T
amb
< 85°C
32
400
275
23.2
8
200
184
76.5
35
40
15
80
30
1
95
1.5
100
9
nF
%
V
mV
kΩ
kΩ
V
mV
kΩ
kΩ
mA
mA
PWM
∆
max.
UVLO
UV
UV
hyst
R
uvl
R
uvl
OVLO
OV
OV
hyst
R
ovl
R
ovl
1. V
ref
parameter indicates global precision of the voltage control loop.
2. Control Gain : A
v
= 95dB ; Input Resistance : R
in
= infinite ; Output Resistance : R
out
= 700MΩ ; Output Source/Sink Current :
I
so
, I
si
= 150µA ; Recommended values for the compensation network are : 22nF & 22kΩ in series between output and ground.
3. V
sense
parameter indicated global precision of the current control loop.
4. Control Gain : A
v
= 105dB ; Input Resistance : R
in
=380kΩ ; Output Resistance : R
out
= 105MΩ ; Output Source/Sink Current :
I
so
, I
si
= 150µA ; Recommended values for the compensation network are : 22nF & 22kΩ in series between output and ground.
5. 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 conditiions, or output short circuit conditions.
6. 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).
7. The given limits comprise the hysteresis (UV
hyst
).
8. It is possible to modify the UVLO and OVLO limits by adding a resistor (to ground or to V
CC
) on the pins UV and OV.
The internal values of the resistor should be taken into account.
3/13
TSM108
DETAILED INTERNAL SCHEMATIC
4/13
TSM108
OSCILLATOR FREQUENCY VERSUS TIMING CAPACITOR
TSM108 AS A STAND ALONE DC/DC CONVERTER FOR CIGARETTE LIGHTER ACCESSORIES
5/13
嵌入式系统
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