ZTP7106
1A, 1.5MHz, Synchronous Step-Down Converter
FEATURES
DESCRIPTION
ZTP7106 is a high efficiency step down DC/DC converter
operated with current mode and constant frequency.
The internal switch and synchronous rectifier are
integrated for high efficiency. External Schottky diodes
are not required. The supply current is only 110µA
during operation and drops to less than 1µA in
shutdown. ZTP7106 can supply 1A of load current from
2.5V to 5.5V supply voltage.
The switching frequency is set at 1.5MHz, allowing the
use of small surface mount inductors and capacitors. It
can run 100% duty cycle for low dropout application.
The output voltage of ZTP7106 is adjustable from the FB
pin.
ZTP7106 is RoHS compliant and Lead (Pb) Free.
1A output current
Current mode operation
High efficiency up to 95%
Shutdown current < 1µA
2.5V to 5.5V supply voltage
Over temperature protection
Constant frequency operation
Full duty ratio, 0 – 100% in dropout
RoHS Compliant and Lead (Pb) Free
APPLICATIONS
Cellular phones
PDAs and smart phones
MP3 players
Digital still cameras
Slim-type DVD
Wireless and DSL card
Microprocessors and DSP core supplies
Portable instruments
Pins Configuration
Top View
TDFN 2x2-6L
Top View
TSOT23-5L
EN
ORDERING INFORMATION
1
5 FB
GND 2
PART NO.
PACKAGE
Output
Ship, Quantity
ZTP7106T
TSOT-23-5L
Adjust.
Tape and Reel
ZTP7106D
TDFN 2x2-6L Adjust.
Tape and Reel
SW 3
4 Vin
NC
1
6 FB
EN 2
5 GND
Vin 3
4 SW
Typical Application Circuit, Adjustable Output Voltage
Vin
L1 = 2.2uH
Vin
Cin =
4.7uF
SW
ZTP7106
EN
C1
R1
Vout
Cout = (Adjustable)
10uF
FB
GND
R2
Vout = VFB × (1 + R1/R2)
with R1 = 300k for typical application,
and C1 should be in the range between 10pF and 47pF for component selection.
DS-19; Feb. 10, 2014
Copyright © ZillTek Technology Corp.
-1-
4F-3, No.5, Technology Rd., Science-Based
Industrial Park, Hsinchu 30078, Taiwan
Tel: (886) 3577 7509; Fax: (886) 3577 7390
Email: sales@zilltek.com
ZTP7106
Absolute Maximum Ratings
Package Thermal Characteristics
(Note 1)
Vin to GND …………………………………………… –0.3V to +6V
SW Voltage to GND ...…………………… –0.3V to Vin+0.3V
EN Voltage to GND ..……………………………… –0.3V to Vin
FB/Vout to GND ..………………………………… –0.3V to Vin
SW Peak Current ………………………………………….………. 3A
Operating Temperature Range ……...… –40°C to +85°C
Junction Temperature ……………..………….…........ +150°C
Storage Temperature Range …………... –65°C to +150°C
Lead Temperature (Soldering 10s) …………...…. +260°C
ESD Classification …………………………………………… Class 2
(Note 2)
TSOT23-5L:
Thermal Resistance, θJA …………..………………… 250°C/W
Thermal Resistance, θJC …………..………………… 130°C/W
TDFN 2x2-6L:
Thermal Resistance, θJA …………..…………………. 120°C/W
Thermal Resistance, θJC …………..…………………… 20°C/W
Recommended Operating Conditions
(Note 3)
Supply Input Voltage ……….………………… +2.5V to +5.5V
Junction Temperature Range…………… –40°C to +125°C
Ambient Temperature Range …………… –40°C to +85°C
CAUTION: Stresses above those listed in “Absolute
Maximum Ratings” may cause permanent damage to
the device. This is a stress only rating and operation of
the device at these or any other conditions above
those indicated in the operational sections of this
specification is not implied.
Pins Description
TSOT TDFN
Symbol
Description
23-5L 2x2-6L
1
2
EN
Enable control input pin.
Electro-Static Discharge Sensitivity
This integrated circuit can be damaged by
ESD. It is recommended that all
integrated circuits be handled with
proper precautions. Failure to observe proper
handling and installation procedures can cause
damage. ESD damage can range from subtle
performance degradation to complete device failure.
2
5
GND
Ground pin.
3
4
SW
Power switch output.
4
3
Vin
Main supply pin.
---
1
NC
5
6
FB
No connected.
Feedback pin.
Vout=0.6×(1+R1/R2).
Add optional C1 to speed up
transient response.
Block Diagram
Vin
EN
Slop Comp
+
_
Current
Sense
Amplifier
Reference
UG
+
_
0.6V
FB
M1
PWM
PWM
Comparator Logic
Error
Amplifier
SW
LG
Oscillator
M2
Clock
+
_
DCC
GND
Zero-current
comparator
DS-19; Feb. 10, 2014
Copyright © ZillTek Technology Corp.
-2-
4F-3, No.5, Technology Rd., Science-Based
Industrial Park, Hsinchu 30078, Taiwan
Tel: (886) 3577 7509; Fax: (886) 3577 7390
Email: sales@zilltek.com
ZTP7106
Electrical Specifications
(Vin = 5V, Vout= 1.8V, L = 2.2uH, Cout = 10uF, TA = 25°C, unless otherwise specified)
PARAMETER
Symbol
Supply Voltage
Output Voltage Line Regulation
Output Voltage Load Regulation
Reference Voltage
Output Range (Adjustable Voltage)
Shutdown Current
Vin
∆Vout
VLR
VREF
Vout
IS
Quiescent Current
SW Leakage Current
IQ
ILEAK
PMOSFET On Resistance*
NMOSFET On Resistance*
RDSONP
RDSONN
PMOSFET Current Limit*
ILIM
Oscillator Frequency
Thermal Shutdown Threshold*
EN High Level Input Voltage
EN Low Level Input Voltage
EN Input Current
FOSC
TS
VENH
VENL
IEN
TEST CONDITIONS
Vin = 2.5V to 5.5V
For adjustable Vout
Vin = 2.5V to 5.5V
VEN = 0V
VEN = Vin,
VFB = VREF × 1.1
No Switching
VEN = 0V,
VSW = 0V or Vin
ISW = 100mA
ISW = −100mA
Duty cycle = 100%
Current Pulse Width < 1ms
MIN
2.5
−3
−3
0.588
−3
0.6
0.1
MAX
UNIT
5.5
3
3
0.612
+3
1
V
%V
%
V
%
µA
110
−1
1.2
−40°C ≤ TA ≤ 85°C
−40°C ≤ TA ≤ 85°C
VEN = 0V to Vin
TYP
µA
1
250
200
mΩ
mΩ
2
A
1.5
160
1.8
1.5
−1
µA
0.4
1
MHz
°C
V
V
µA
* Guaranteed by design not for test.
Note 1: Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These
are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated
in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may
affect device reliability.
Note 2: θJA is measured in the natural convection at TA = 25°C on a low effective single layer thermal conductivity test
board of JEDEC 51-3 thermal measurement standard. Pin 2 of TSOT23-5 packages is the case position for θJC
measurement. Measured at the exposed pad of the package.
Note 3: The device is not guaranteed to function outside its operating conditions.
DS-19; Feb. 10, 2014
Copyright © ZillTek Technology Corp.
-3-
4F-3, No.5, Technology Rd., Science-Based
Industrial Park, Hsinchu 30078, Taiwan
Tel: (886) 3577 7509; Fax: (886) 3577 7390
Email: sales@zilltek.com
ZTP7106
Typical Characteristics
Startup
(Vin=5.0V, Vout=1.8V, Iload=1A)
Shutdown
(Vin=5.0V, Vout=1.8V, Iload=1A)
Vin
5V/div
Ven
5V/div
Vin
5V/div
Ven
5V/div
Vout
1V/div
Vout
1V/div
Isw
1A/div
Isw
1A/div
10us/div
200us/div
Output Ripple
(Vin=5.0V, Vout=1.8V, Iload=1A)
Load Transient
(Vin=5.0V, Vout=1.8V, Iload=0.05A~1A)
Vout
50mV/div
Vout
10mV/div
IL
1A/div
Isw
1A/div
500ns/div
200us/div
Short Protection/Current limit
(Vin=5.0V, Vout=1.8V, Iload=0A~short)
Vout
1V/div
Isw
2A/div
200us/div
Light Load Efficiency Curve
DS-19; Feb. 10, 2014
Copyright © ZillTek Technology Corp.
Efficiency vs. Load Current Curve
-4-
4F-3, No.5, Technology Rd., Science-Based
Industrial Park, Hsinchu 30078, Taiwan
Tel: (886) 3577 7509; Fax: (886) 3577 7390
Email: sales@zilltek.com
ZTP7106
FUNCTIONAL DESCRIPTION
Dropout Operation
Overview
ZTP7106 allows the main switch to remain on for more
than one switching cycle and increases the duty cycle
while the input voltage is dropping close to the output
voltage. When the duty cycle reaches 100%, the main
switch is held on continuously to deliver current to the
output up to the P MOSFET current limit. The output
voltage then is the input voltage minus the voltage drop
across the main switch and the inductor.
The ZTP7106 is a constant frequency current mode
PWM step down converter. ZTP7106 is optimized for low
voltage, Li-ion battery, powered applications where high
efficiency and small size are critical. The device
integrates both a main switch and a synchronous
rectifier, which provides high efficiency and eliminates
an external Schottky diode. ZTP7106 can achieve 100%
duty cycle. The duty cycle D of a step down converter is
defined as:
Short Circuit Protection
Where TON is the main switch on time, FOSC is the
oscillator frequency (1.5MHz), Vout is the output
voltage and Vin is the input voltage.
The ZTP7106 has short circuit protection. When the
output is shorted to ground, the oscillator frequency is
reduced to prevent the inductor current from increasing
beyond the P MOSFET current limit. The frequency will
return to the normal values once the short circuit
condition is removed and the Vout reaches regulated
voltage.
Current Mode PWM Control
Maximum Load Current
Slope compensated current mode PWM control
provides stable switching and cycle-by-cycle current limit
for superior load and line response and protection of the
internal main switch and synchronous rectifier. ZTP7106
switches at a constant frequency (1.5MHz) and regulates
the output voltage. During each cycle the PWM
comparator modulates the power transferred to the
load by changing the inductor peak current based on the
feedback error voltage. During normal operation, the
main switch is turned on for a certain time to ramp the
inductor current at each rising edge of the internal
oscillator, and switched off when the peak inductor
current is above the error voltage. When the main
switch is off, the synchronous rectifier will be turned on
immediately and stay on until either the next cycle starts
or the inductor current drops to zero. The device skips
pulses to improve efficiency at light load.
The ZTP7106 can operate down to 2.5V input voltage;
however the maximum load current decreases at lower
input due to large IR drop on the main switch and
synchronous rectifier. The slope compensation signal
reduces the peak inductor current as a function of the
duty cycle to prevent sub-harmonic oscillations at duty
cycles greater than 50%. Conversely the current limit
increases as the duty cycle decreases.
D = TON × FOSC × 100% ≈
Vout
× 100%
Vin
DS-19; Feb. 10, 2014
Copyright © ZillTek Technology Corp.
-5-
4F-3, No.5, Technology Rd., Science-Based
Industrial Park, Hsinchu 30078, Taiwan
Tel: (886) 3577 7509; Fax: (886) 3577 7390
Email: sales@zilltek.com
ZTP7106
required. The ripple voltage is given by:
APPLICATION INFORMATION
ΔVO = ΔIL [ESR + 1/(8 × f × CO)]
Inductor Selection
Output Voltage Programming
(Adjustable Voltage Version)
A 2.2μH to 4.7μH is recommended for general used. The
value of inductor depends on the operating frequency.
Higher frequency allows smaller inductor and capacitor
but increases internal switching loss. Two inductor
parameters should be considered, current rating and
DCR. The inductor with the lowest DCR is chosen for the
highest efficiency.
The inductor value can be calculated as:
The output voltage of ZTP7106 is set by the resistor
divider according to the following formula:
VOUT = VFB × (1 + R1/R2)
R1 is the upper resistor of the voltage divider. For
transient response reasons, a small feed-forward
capacitor (CF) is required in parallel to the upper
feedback resistor, and 22pF is recommended.
L ≥ [VOUT/(f × ΔIL)](1 – VOUT/VIN)
ΔIL: inductor ripple current, which is defined as:
ΔIL = VOUT[(1 – VOUT/VIN)/(L × f)]
≈ α × IO-MAX
Checking Transient Response
(General Setting)
(α = 0.2~0.4)
The regulator loop response can be checked by looking
at the load transient response. Switching regulators take
several cycles to respond to a step in load current.
When a load step occurs, VOUT will be shifted
immediately by an amount equal to (ΔILOAD × ESR),
where ESR is the effective series resistance of COUT.
ΔILOAD will also begin to charge or discharge COUT, which
generates a feedback error signal. Then the regulator
loop will act to return VOUT to its steady state value.
During this recovery time, VOUT can be monitored for
overshoot or ringing that will indicate the stability
problem.
The discharged bypass capacitors are effectively put in
parallel with COUT, causing a rapidly drop in VOUT. No
regulator can deliver enough current to prevent this
problem if the load switch resistance is low and it is
driven quickly. The only solution is to limit the rise time
of the switch drive, so that the load rise time will be
limited to approximately (25 × CLOAD).
The inductor should be rated for the maximum output
current (IO-MAX) plus the inductor ripple current (ΔIL) to
avoid saturation. The maximum inductor current (IL-MAX)
is given by:
IL-MAX = IO-MAX +ΔIL/2
Capacitor Selection
The small size of ceramic capacitors are ideal for
ZTP7106 applications. X5R and X7R types are
recommended because they retain their capacitance
over wider voltage and temperature ranges than other
types, such as Y5V or Z5U. A 4.7μF input capacitor and a
10μF output capacitor are sufficient for most ZTP7106
applications.
When selecting an output capacitor, consider the output
ripple voltage and the ripple current. The ESR of
capacitor is a major factor to the output ripple. For the
best performance, a low ESR output capacitor is
DS-19; Feb. 10, 2014
Copyright © ZillTek Technology Corp.
-6-
4F-3, No.5, Technology Rd., Science-Based
Industrial Park, Hsinchu 30078, Taiwan
Tel: (886) 3577 7509; Fax: (886) 3577 7390
Email: sales@zilltek.com
ZTP7106
PACKAGE DIMENSION (TSOT23-5L)
D
C
B
e
b
A
H
A1
L
Symbol
A
A1
B
b
C
D
e
H
L
Dimensions in mm
Min
Max
0.700
1.100
0.000
0.130
1.500
1.700
0.300
0.559
2.500
3.100
2.800
3.100
0.950 BSC
0.080
0.200
0.200
0.800
DS-19; Feb. 10, 2014
Copyright © ZillTek Technology Corp.
Dimensions in Inch
Min
Max
0.028
0.043
0.000
0.005
0.059
0.067
0.012
0.022
0.098
0.122
0.110
0.122
0.037 BSC
0.003
0.008
0.008
0.031
-7-
4F-3, No.5, Technology Rd., Science-Based
Industrial Park, Hsinchu 30078, Taiwan
Tel: (886) 3577 7509; Fax: (886) 3577 7390
Email: sales@zilltek.com
ZTP7106
PACKAGE DIMENSION (TDFN 2x2-6L)
D
D2
L
E
E2
SEE DETAIL A
1
e
A
b
A3
A1
2
1
DETAIL A
A
DIMENSION (MM)
MIN
NOM
MAX
0.700
--0.800
DIMENSION (INCH)
MIN
NOM
MAX
0.028
--0.031
A1
0.000
---
0.050
0.000
---
0.002
A3
0.175
---
0.250
0.007
---
0.010
b
0.200
---
0.350
0.008
---
0.014
D
1.950
2.000
2.050
0.077
0.079
0.081
D2
1.000
---
1.450
0.039
---
0.057
E
1.950
2.000
2.050
0.077
0.079
0.081
E2
0.500
---
0.850
0.020
---
0.033
SYMBOLS
e
L
0.650
0.250
DS-19; Feb. 10, 2014
Copyright © ZillTek Technology Corp.
---
0.026
0.400
-8-
0.010
---
0.016
4F-3, No.5, Technology Rd., Science-Based
Industrial Park, Hsinchu 30078, Taiwan
Tel: (886) 3577 7509; Fax: (886) 3577 7390
Email: sales@zilltek.com