Philips TEA1200TS User Manual
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INTEGRATED CIRCUITS
DATA SH EET
TEA1200TS
0.95 V starting DC-to-DC converter
with low battery indicator
Product specification 2002 May 14
Philips Semiconductors Product specification
0.95 V starting DC-to-DC converter
with low battery indicator
FEATURES
• Complete DC-to-DC converter circuit and battery low
detector
• Configurablefor1, 2 or 3-cellNickel-Cadmium(NiCd)or
Nickel Metal Hydride (NiMH) batteriesand 1 LithiumIon
(Li-Ion) battery
• Guaranteed DC-to-DC converter start-up from 1-cell
NiCd or NiMH battery, even with a load current
• Upconversion or downconversion
• Internal power MOSFETs featuring a low R
approximately 0.1 Ω
• Synchronous rectification for high efficiency
• Soft start
• PWM-only operating option
• Stand-alone low battery detector requires no additional
supply voltage
• Low battery detection level at 0.90 V, externally
adjustable to a higher level
• Adjustable output voltages
• Shut-down function
• Small outline package
• 0.6 µm BICMOS process.
APPLICATIONS
• Cellular phones
• Cordless phones
• Personal Digital Assistants (PDAs)
• Portable audio players
• Pagers
• Mobile equipment.
DSon
of
TEA1200TS
GENERAL DESCRIPTION
The TEA1200TS is a fully integrated battery power unit
including a high-efficiency DC-to-DC converterwhich runs
from a 1-cell NiCd or NiMH battery and a low battery
detector. The circuit can be arranged in several ways to
optimize the application circuit of a power supply system.
Therefore, the DC-to-DC converter can be arranged for
upconversion or downconversion and the low battery
detector can be configured for several types of batteries.
Accurate low battery detection is possible while all other
blocks are switched off.
The DC-to-DC converter features efficient, compact and
dynamic power conversion using a digital control concept
comparable with Pulse Width Modulation (PWM) and
Pulse Frequency Modulation (PFM), integrated CMOS
power switches with a very low R
synchronous rectification.
The device operates at a switching frequency of 600 kHz
which enables the use of external components with
minimum size. The switching frequency can be
synchronized to an external high frequency clock signal.
Optionally, the device can be kept in PWM control mode
only. Deadlock is prevented by an on-chip undervoltage
lockout circuit.
Active current limiting enables efficient conversion in
pulsed-load systems such as Global System for Mobile
communication (GSM) and Digital Enhanced Cordless
Telecommunications (DECT).
The low battery detector has a built-in detection level
which is optimum for a 1-cell NiCd or NiMH battery.
DSon
and fully
ORDERING INFORMATION
TYPE
NUMBER
TEA1200TS SSOP16 plastic shrink small outline package; 16 leads; body width 4.4 mm SOT369-1
2002 May 14 2
NAME DESCRIPTION VERSION
PACKAGE
Philips Semiconductors Product specification
0.95 V starting DC-to-DC converter
TEA1200TS
with low battery indicator
QUICK REFERENCE DATA
SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT
DC-to-DC converter
UPCONVERSION
V
i(up)
V
o(up)
V
i(start)
V
o(uvlo)
DOWNCONVERSION
V
i(dwn)
V
o(dwn)
CURRENT LEVELS
I
q(DC/DC)
I
shdwn
I
LX(max)
∆I
lim
POWER MOSFETS
R
DSon(N)
R
DSon(P)
EFFICIENCY
η efficiency upconversion see Fig.8; Voup to 3.3 V
TIMING
f
sw
f
i(sync)
t
start
General characteristics
V
ref
input voltage V
output voltage V
− 5.50 V
i(start)
− 5.50 V
o(uvlo)
start-up input voltage IL< 10 mA 0.93 0.96 1.00 V
undervoltage lockout voltage note 1 2.0 2.2 2.4 V
input voltage V
− 5.50 V
o(uvlo)
output voltage 1.30 − 5.50 V
quiescent current at pin
− 110 −µA
UPOUT/DNIN
current in shut-down mode V
maximum continuous current at
LBI1=VI(up)
T
=80°C −−1.0 A
amb
= 1.2 V − 65 −µA
pins LX1 and LX2
current limit deviation I
set to 1.0 A
lim
upconversion −12 − +12 %
downconversion −12 − +12 %
drain-to-sourceon-state resistance
Tj=27°C; IDS= 100 mA − 110 200 mΩ
NFET
drain-to-sourceon-state resistance
Tj=27°C; IDS= 100 mA − 125 250 mΩ
PFET
V
= 1.2 V; IL= 100 mA − 84 − %
i
V
= 2.4 V; IL=10mA − 92 − %
i
switching frequency PWM mode 480 600 720 kHz
synchronization clock input
6 1320MHz
frequency
start-up time − 10 − ms
reference voltage 1.165 1.190 1.215 V
Note
1. The undervoltage lockoutlevel showswide specification limits since it decreases withincreasing temperature.When
the temperature increases, the minimum supply voltage of the digital control part of the IC decreases and therefore
thecorrect operation of this functionis guaranteed overthe whole temperaturerange. The undervoltagelockout level
is measured at pin UPOUT/DNIN.
2002 May 14 3
Philips Semiconductors Product specification
0.95 V starting DC-to-DC converter
with low battery indicator
BLOCK DIAGRAM
UPOUT/DNIN
n.c.
3
6
UPOUT/DNIN
4
INTERNAL
SUPPLY
8
GND
TEA1200TS
FB0
12
ref
V
ref
V
11
VOLT AGE
REFERENCE
ref
V
7
MBL409
TEA1200TS
9
TIME
COUNTER
AND
CIRCUIT
START-UP
sense FET
P-type POWER FET
DETECTOR
LOW BATTERY
1
10
5
16
MODE GEARBOX
CONTROL LOGIC
COMPARATOR
CURRENT LIMIT
ref
V
TEMPERATURE
N-type
POWER
PROTECTION
FET
FET
sense
DIGITAL CONTROLLER
GATE
SYNC
13 MHz
OSCILLATOR
SHDWN0
1413 2 15
SYNC/PWM U/D
GND0
Fig.1 Block diagram.
handbook, full pagewidth
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2002 May 14 4
LBI1
LBO
LX1
LX2
ILIM
Philips Semiconductors Product specification
0.95 V starting DC-to-DC converter
with low battery indicator
PINNING
SYMBOL PIN DESCRIPTION
LX1 1 inductor connection 1
SHDWN0 2 DC-to-DC converter shut-down
input
UPOUT/DNIN 3 up mode: DC-to-DC converter
output; down mode DC-to-DC
converter input
UPOUT/DNIN 4 up mode: DC-to-DC converter
output; down mode DC-to-DC
converter input
ILIM 5 current limiting resistor
connection
n.c. 6 not connected
V
ref
GND 8 internal supply ground
LBI1 9 low battery detector input 1
LBO 10 low battery detector output
V
ref
FB0 12 DC-to-DC converter feedback
GND0 13 DC-to-DC converter ground
SYNC/PWM 14 synchronization clock input or
U/D 15 conversion mode selection input
LX2 16 inductor connection 2
7 reference voltage input
11 reference voltage input
input
PWM-only selection input
handbook, halfpage
UPOUT/DNIN
UPOUT/DNIN
LX1
1
SHDWN0
ILIM
n.c.
V
ref
GND
2
3
4
TEA1200TS
5
6
7
8
Fig.2 Pin configuration.
TEA1200TS
LX2
16
U/D
15
14
SYNC/PWM
13
GND0
12
FB0
11
V
ref
10
LBO
9
LBI1
MBL419
FUNCTIONAL DESCRIPTION
Control mechanism
The TEA1200TS DC-to-DC converter is able to operate in
the PFM (discontinuous conduction) or PWM (continuous
conduction) operating mode. All switching actions are
completely determined by a digital control circuit which
usesthe output voltage levelasits control input. Thisnovel
digital approach enables the use of a new pulse width and
frequency modulation scheme, which ensures optimum
power efficiency over the complete range of operation of
the converter.
When high output power is requested, the device will
operate in the PWM operating mode. This results in
minimumAC currents in the circuitcomponentsandhence
optimum efficiency, minimum costs and low EMC. In this
operating mode, the output voltage is allowed to vary
between two predefined voltage levels. As long as the
output voltage stays within this so-called window,
switching continues in a fixed pattern.
2002 May 14 5
When the output voltage reaches one of the window
borders, the digital controller immediately reacts by
adjusting the pulse width and inserting a current step in
such a waythat the output voltage stayswithin the window
with higher or lower current capability. This approach
enables very fast reaction to load variations. Figure 3
shows the response of the converter to a sudden load
increase. The upper trace shows the output voltage.
The ripple on top of the DC level is a result of the current
in the output capacitor, which changes in sign twice per
cycle, times the internal Equivalent Series Resistance
(ESR) of the capacitor. After each ramp-down of the
inductor current, i.e. when the ESR effect increases the
output voltage, the converter determines what to do in the
next cycle. As soon as more load current istaken from the
output the output voltage starts to decay.
Philips Semiconductors Product specification
0.95 V starting DC-to-DC converter
with low battery indicator
When the output voltage becomes lower than the low limit
of the window, a corrective actionis taken by a ramp-up of
theinductor current duringa much longertime. As aresult,
the DC current level is increasedand normalPWM control
can continue. The output voltage (including ESR effect) is
again within the predefined window.
Figure 4 shows the spread of the output voltage window.
The absolute value is mostly dependent on spread, while
the actual window size [V
wdw(high)
affected. For one specific device, the output voltage will
not vary more than 2% (typical value).
handbook, full pagewidth
V
o
− V
wdw(low)
load increase
] is not
start corrective action
TEA1200TS
In low output power situations, the TEA1200TS will switch
over to PFM operating mode. In this mode, regulation
information from an earlier PWM operating mode is used.
This results in optimum inductor peak current levels in the
PFM mode, which are slightly larger than the inductor
ripple current in the PWM mode. As a result, the transition
between PFM and PWM mode is optimum under all
circumstances. In the PFM mode the TEA1200TS
regulates the output voltage to the high window limit as
shown in Fig.3.
high window limit
low window limit
time
I
L
time
MGK925
Fig.3 Response to load increase.
2002 May 14 6
Philips Semiconductors Product specification
0.95 V starting DC-to-DC converter
with low battery indicator
handbook, full pagewidth
V
O (typ)
V
wdw(high)
2%
V
wdw(low)
typical situation
maximum positive spread of V
+2%
V
wdw(high)
V
wdw(low)
maximum negative spread of V
2%
−2%
O
V
wdw(high)
V
wdw(low)
2%
upper specification limit
lower specification limit
O
TEA1200TS
MGU269
Fig.4 Output voltage window spread.
Synchronous rectification
For optimum efficiency over the whole load range,
synchronous rectifiers within the TEA1200TS ensure that
during the whole second switching phase, all inductor
current will flow through the low-ohmic power MOSFETs.
Special circuitry is included which detects when the
inductorcurrentreaches zero. Followingthisdetection,the
digital controller switches off the power MOSFET and
proceeds with regulation.
Start-up
Start-up from low input voltage in the boost mode is
realized by anindependent start-up oscillator,which starts
switching the N-type power MOSFET as soon as the
low-battery detector detects a sufficiently high voltage.
The inductor current is limited internally to ensure
soft-starting. The switch actions of the start-up oscillator
will increase the output voltage. As soon as the output
voltage is high enough for normal regulation, the digital
control system will take control over the power MOSFETs.
Undervoltage lockout
As a result of too high a load or disconnection of the input
power source, the output voltage can drop so low that
normal regulation cannot beguaranteed. In this event, the
device switches back to start-up mode. If the output
voltage drops even further, switching is stopped
completely.
Shut-down
When the shut-down input is set HIGH, the DC-to-DC
converter disables both switches and power consumption
is reduced to a few microamperes.
Power switches
The power switches in the IC are one N-type and one
P-type power MOSFET, both having a typical
drain-to-source resistance of 100 mΩ. The maximum
continuous current in the power switches is 1.0 A at
T
=80°C.
amb
2002 May 14 7
Philips Semiconductors Product specification
0.95 V starting DC-to-DC converter
with low battery indicator
Temperature protection
When the DC-to-DC converter operates in the PWM
mode, and thedie temperaturegets toohigh (typical value
is 190 °C), the converter will stop operating. It resumes
operation when the die temperature falls below 90 °C
again. As a result, low frequency cycling between the on
and off state willoccur. It should be noted that in the event
of device temperatures at the cut-off limit, the application
differs strongly from maximum specifications.
Current limiters
If the current in one of the power switches exceeds the
programmed limit in the PWM mode, the current ramp is
stopped immediately and the next switching phase is
entered. Current limiting is required to keep power
conversion efficient during temporary high loads.
Furthermore, current limiting protects the IC against
overload conditions, inductor saturation, etc.
The current limiting level is set by an external resistor
whichmust be connected betweenpin ILIMand ground for
downconversion, or betweenpins ILIM and UPOUT/DNIN
for upconversion.
External synchronization and PWM-only mode
If an external high-frequency clock or a HIGH level is
applied to pin SYNC/PWM, the TEA1200TSwill usePWM
regulation independent of the load applied.
In the event that a high-frequency clock is applied, the
switching frequency in the PWM mode will be exactly that
frequency divided by 22. In the PWM mode the quiescent
current of the device increases.
In the event that no external synchronization or PWM
mode selection is necessary, pin SYNC/PWM must be
connected to ground.
TEA1200TS
Behaviour when the input voltage exceeds the
specified range
In general, an inputvoltage exceeding the specified range
isnot recommended sinceinstability may occur.There are
two exceptions:
1. Upconversion: at an input voltage higher than the
targetoutput voltage, butupto 5.5 V, theconverter will
stop switching and the external Schottky diode will
take over. The output voltage will equal the input
voltageminus thediode voltage drop.Since all current
flows through the external diode in this situation, the
current limiting function is not active.
In the PWM mode, the P-type power MOSFET is
always on when the input voltage exceeds the target
output voltage. The internal synchronous rectifier
ensures that the inductor current does not fall below
zero. As a result, the achieved efficiency is higher in
this situation than standard PWM-controlled
converters achieve.
2. Downconversion: when the input voltage islower than
the target output voltage, but higher than 2.2 V, the
P-type power MOSFET will stay conducting resulting
in the output voltage being equal to the input voltage
minussomeresistive voltage drop. Thecurrentlimiting
function remains active.
Low battery detector
The low battery detector is an autonomous circuit which
can work at an input voltage down to 0.90 V. It is always
on, even when all other blocks are in the shut-down mode.
The low battery input (pin LBI1) is adjusted to accept a
1-cell NiCd or NiMH battery voltage directly. Hysteresis is
included for proper operating.
The output of the low battery detector (pin LBO) is an
open-collector output. The output is high (i.e. no current is
sunk by the collector) when the input voltage of the
detector is below the lower detection level.
2002 May 14 8
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