MAX1958ETP [MAXIM]
SMPS Controller ; SMPS控制器\n
| 型号： | MAX1958ETP |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | SMPS Controller
|
| 文件： | 总24页 (文件大小：795K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-2659; Rev 0; 10/02
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
General Description
Features
The MAX1958/MAX1959 power amplifier (PA) power-
management ICs (PMICs) integrate an 800mA, dynami-
cally adjustable step-down converter, a 5mA Rail-to-
Rail® operational amplifier (op amp), and a precision
temperature sensor to power a heterojunction bipolar
transistor (HBT) PA in W-CDMA and N-CDMA cell
phones.
ꢀ Step-Down Converter
Dynamically Adjustable Output Voltage from
0.75V to 3.4V (MAX1958)
Dynamically Adjustable Output Voltage from
1V to 3.6V (MAX1959)
800mA Guaranteed Output Current
130mV IC Dropout at 600mA Load
Low Quiescent Current
The high-efficiency, pulse-width modulated (PWM), DC-
to-DC buck converter is optimized to provide a guaran-
teed output current of 800mA. The output voltage is
dynamically controlled to produce any fixed-output volt-
age in the range of 0.75V to 3.4V (MAX1958) or 1V to
3.6V (MAX1959), with settling time less than 30µs for a
full-scale change in voltage and current. The 1MHz PWM
switching frequency allows the use of small external
components while pulse-skip mode reduces quiescent
current to 190µA with light loads. The converter utilizes a
low on-resistance internal MOSFET switch and synchro-
nous rectifier to maximize efficiency and minimize
external component count. The 100% duty-cycle opera-
tion allows for an IC dropout voltage of only 130mV (typ)
at 600mA load.
190µA (typ) in Skip Mode (MAX1958)
3mA (typ) in PWM Mode
0.1µA (typ) in Shutdown Mode
1MHz Fixed-Frequency PWM operation
16% to 100% Duty-Cycle Operation
No External Schottky Diode Required
Soft-Start
ꢀ Operational Amplifier
5mA Rail-to-Rail Output
Active Discharge in Shutdown
800kHz Gain-Bandwidth Product
120dB Open-Loop Voltage Gain (R = 100kΩ)
L
ꢀ Temperature Sensor
Accurate Sensor -11.7mV/°C Slope
-40°C to +125°C-Rated Temperature Range
The micropower op amp is used to provide bias to the
HBT PA to maximize efficiency. The amplifier features
active discharge in shutdown for full PA bias control. It
has 5mA rail-to-rail drive capability, 800kHz gain-band-
width product, and 120dB open-loop voltage gain.
ꢀ 20-Pin Thin QFN (5mm ✕ 5mm), 0.8mm Height (max)
Ordering Information
The precision temperature sensor measures tempera-
tures between -40°C to +125°C, with linear tempera-
ture-to-voltage analog output characteristics.
PART
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
20 Thin QFN-EP*
20 Thin QFN-EP
MAX1958ETP
MAX1959ETP
The MAX1958/MAX1959 are available in a 20-pin 5mm ✕
5mm thin QFN package (0.8mm max height).
*EP = Exposed paddle.
Pin Configuration
TOP VIEW
Applications
W-CDMA and N-CDMA Cellular Phones
AOUT
SHDN2
AGND
TOUT
REF
1
2
3
4
5
15 PWM
14 INP
13 IN
Wireless PDAs and Modems
MAX1958/
MAX1959
12
11
LX
PGND
Typical Operating Circuit and Functional Diagram appear at
end of data sheet.
THIN QFN
5mm x 5mm
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
ABSOLUTE MAXIMUM RATINGS
IN, INP, OUT, ADJ, SHDN1, SHDN2,
Continuous Power Dissipation (T = +70°C)
20-Pin Thin QFN 5mm x 5mm
A
SHDN3, PWM, V to PGND ...................................-0.3V to +6V
CC
(derate 20.8mW/°C above +70°C).............................1670mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
AGND to PGND.....................................................-0.3V to +0.3V
COMP, REF to AGND ....................................-0.3 to (V + 0.3V)
IN
VCC
IN+, IN-, AOUT, TOUT to AGND ................-0.3 to (V
+ 0.3V)
LX Current (Note 1)............................................................. 1.6A
Output Short-Circuit Duration.....................................Continuous
Note 1: LX has internal clamp diodes to PGND and INP. Applications that forward bias these diodes should take care not to exceed
the IC’s package power dissipation limits.
Stresses beyond those listed under “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 for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS (STEP-DOWN CONVERTER)
(V
= V = V
= V
= 3.6V, V
= V
= V
= V
= V
= 0, V
= 1.25V, COMP = IN- = IN+ = AOUT
INP
IN
VCC
SHDN1
PWM
PGND
AGND
SHDN2
SHDN3
ADJ
= TOUT = unconnected, C
= 0.1µF, T = 0°C to +85°C, V
for MAX1958 = 2.2V, V
for MAX1959 = 1.7V, unless otherwise
REF
A
OUT
OUT
noted. Typical values are at T = +25°C.)
A
PARAMETER
CONDITIONS
MIN
2.6
TYP
MAX
5.5
UNITS
Supply Voltage Range
V
V
Undervoltage Lockout Threshold
Rising or falling, hysteresis is 1%
MAX1958, PWM = AGND
MAX1959, PWM = AGND
2.20
2.35
190
280
3
2.55
300
450
µA
mA
µA
µA
Quiescent Current
V
= V
IN
PWM
MAX1958
MAX1959
295
330
0.1
550
600
6
Quiescent Current in Dropout
Shutdown Supply Current
V
= 0
SHDN1
ERROR AMPLIFIER
V
V
V
V
V
V
V
V
V
V
V
V
= 1.932V, I
= 0.426V, I
= 0.426V, I
= 0 to 600mA, V
= V = 3.8V
3.38
0.739
0.739
3.58
0.985
0.985
2
3.40
0.750
0.750
3.60
1.00
1.00
4
3.42
0.761
0.761
3.62
1.015
1.015
6
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
OUT
OUT
OUT
OUT
ADJ
ADJ
LOAD
LOAD
LOAD
PWM
IN
OUT Voltage Accuracy
(MAX1958)
= 0 to 30mA, V
= 0 to 30mA, V
= 0
V
V
PWM
PWM
= V = 4.2V
IN
= 2.2V, I
= 0.9V, I
= 0.9V, I
= 0.75V
= 3.4V
= 0 to 600mA, V
= V = 4V
LOAD
LOAD
LOAD
PWM IN
OUT Voltage Accuracy
(MAX1959)
= 0 to 30mA, V
= 0
PWM
PWM
= 0 to 30mA, V
= V = 4.2V
IN
OUT Input Current (MAX1958)
OUT Input Current (MAX1959)
µA
µA
11
17
25
= 1V
2.5
4.0
6.5
= 3.6V
10
16
23
ADJ Input Current (MAX1958)
ADJ Input Current (MAX1959)
= 0.426V to 1.932V
= 0.9V to 2.2V
-150
-150
+1
+150
+150
nA
nA
+1
Positive COMP Output Current
(MAX1958)
V
V
= 1V, V
= 1.5V, V = 1.25V
COMP
-27
-27
-14
-14
-7
-7
µA
µA
ADJ
ADJ
OUT
OUT
Positive COMP Output Current
(MAX1959)
= 1V, V
= 1V, V
= 1.25V
COMP
2
_______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
ELECTRICAL CHARACTERISTICS (STEP-DOWN CONVERTER) (continued)
(V
= V = V
= V
= 3.6V, V
= 0.1µF, T = 0°C to +85°C, V
= V
= V
= V
= V
= 0, V
= 1.25V, COMP = IN- = IN+ = AOUT
for MAX1959 = 1.7V, unless otherwise
INP
IN
VCC
SHDN1
PWM
A
PGND
AGND
SHDN2
SHDN3
ADJ
= TOUT = unconnected, C
for MAX1958 = 2.2V, V
REF
OUT
OUT
noted. Typical values are at T = +25°C.)
A
PARAMETER
CONDITIONS
= 2V, V = 1.25V
MIN
TYP
MAX
UNITS
Negative COMP Output Current
(MAX1958)
V
V
= 1V, V
= 1V, V
7
14
27
µA
ADJ
ADJ
OUT
COMP
Negative COMP Output Current
(MAX1959)
= 1.4V, V
= 1.25V
7
14
27
µA
OUT
COMP
REFERENCE
REF Output Voltage
REF Load Regulation
Undervoltage Lockout Threshold
Supply Rejection
1.225
0.85
1.250
2.50
1.00
0.07
1.275
6.25
1.10
1.7
V
mV
V
10µA < I
< 100µA
REF
Rising or falling, 1% hysteresis
2.6V < V < 5.5V
mV/V
IN
CONTROLLER
I
I
I
I
= 180mA, V = 3.6V
0.21
0.25
0.18
0.21
0.5
0.40
0.5
LX
LX
LX
LX
IN
P-Channel On-Resistance
Ω
= 180mA, V = 2.6V
IN
= 180mA, V = 3.6V
0.30
0.35
IN
N-Channel On-Resistance
Ω
V/A
A
= 180mA, V = 2.6V
IN
Current-Sense Transresistance
P-Channel Current-Limit
Threshold
1.1
1.37
0.15
-0.5
1.6
P-Channel Pulse-Skipping
Current Threshold
V
V
= 0
= V
= 0
0.12
0.17
A
A
PWM
PWM
PWM
N-Channel Current-Limit
Threshold
IN
N-Channel Zero-Crossing
Comparator
V
V
20
mA
LX Leakage Current
LX RMS Current
= 5.5V
-20.0
100
+0.1
+20.0
1.0
µA
A
IN
(Note 1)
Maximum Duty Cycle
%
V
V
= 0
0
PWM
PWM
Minimum Duty Cycle
%
= V = 4.2V
16
IN
Oscillator Frequency
Thermal-Shutdown Threshold
LOGIC INPUTS (PWM, SHDN1)
Logic Input High
0.85
1.6
1.00
160
1.15
MHz
Hysteresis = +15°C
2.6 V < V < 5.5 V
°C
V
V
IN
Logic Input Low
2.6 V < V < 5.5 V
0.6
1
IN
Logic Input Current
V
= 5.5V
0.1
µA
IN
_______________________________________________________________________________________
3
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
ELECTRICAL CHARACTERISTICS (OP AMP)
(V
= V = V
= V
= 2.7V, V
= V
/2, R = ∞ connected from AOUT to V
/2, V
= V
= V
=
SHDN1
INP
IN
= V
VCC
= V
SHDN2
AOUT
VCC
L
VCC
PGND
AGND
V
= 0, OUT = LX = TOUT = REF = COMP = unconnected, V
= 0, T = 0°C to +85°C, unless otherwise
SHDN3
PWM
ADJ
CM A
noted. Typical values are at T = +25°C.)
A
PARAMETER
CONDITIONS
MIN
TYP
MAX
5.5
UNITS
Supply Voltage Range
2.6
V
V
V
V
V
V
V
V
= 2.6V
= 5V
320
375
0.1
0.4
10
1
800
900
2.0
VCC
VCC
Supply Current
µA
= 0, V
= 5.5V
SHDN2
VCC
Input Offset Voltage
Input Bias Current
Input Offset Current
Input Resistance
- 0.1V ≤ V
- 0.1V ≤ V
- 0.1V ≤ V
≤ V
≤ V
≤ V
+ 0.1V
+ 0.1V
+ 0.1V
3.0
mV
nA
AGND
AGND
AGND
CM
CM
CM
VCC
VCC
VCC
100
10
nA
- V
IN+
≤ 10mV
4
MΩ
IN-
Input Common-Mode Voltage
V
+
VCC
0.1
-0.1
60
V
Range, V
CM
Common-Mode Rejection Ratio,
CMRR
V
- 0.1V ≤ V
≤ V
+ 0.1V
80
90
dB
dB
AGND
CM
VCC
Power-Supply Rejection Ratio,
PSRR
2.6V < V
< 5.5V
70
VCC
V
V
+ 0.05V ≤ V
- 0.05V
≤
≤
AGND
AOUT
R = 100kΩ
120
110
L
VCC
Large-Signal Voltage Gain, AVOL
dB
V
V
+ 0.20V ≤ V
AGND
AOUT
R = 2kΩ
L
85
- 0.20V
VCC
R = 100kΩ
1
L
Output Voltage Swing High, VOH V
-V
mV
mV
mA
V
VCC VOH
R = 2kΩ
L
35
1
90
90
R = 100kΩ
L
Output Voltage Swing Low, VOL
Output Short-Circuit Current
SHDN2 Logic Low
V
- V
VOL AGND
RL = 2kΩ
30
11
30
Sourcing, V
= 5V
VCC
Sinking, V
= 5V
VCC
0.3 x
2.6V < V
2.6V < V
< 5.5V
< 5.5V
VCC
V
VCC
0.7 x
SHDN2 Logic High
V
VCC
V
VCC
SHDN2 Input Current
Gain Bandwidth Product, GBW
Phase Margin, φM
0 < V
< V
0.5
1
120
nA
MHz
Degrees
dB
SHDN2
VCC
70
20
0.4
52
0.1
Gain Margin, GM
Slew Rate, SR
V/µs
Input Voltage Noise Density
Input Current Noise Density
Capacitive-Load Stability
Shutdown Delay Time
Enable Delay Time
f = 10kHz
f = 10kHz
nV/√Hz
pA/√Hz
pF
AVCL = 1V/V (Note 2)
470
3
4
µs
µs
4
_______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
ELECTRICAL CHARACTERISTICS (OP AMP) (continued)
(V
= V = V
= V
= 2.7V, V
= V
/2, R = ∞ connected from AOUT to V
/2, V
= V
= V
=
SHDN1
INP
IN
= V
VCC
= V
SHDN2
AOUT
VCC
L
VCC
PGND
AGND
V
= 0, OUT = LX = TOUT = REF = COMP = unconnected, V
= 0, T = 0°C to +85°C, unless otherwise
SHDN3
PWM
ADJ
CM A
noted. Typical values are at T = +25°C.)
A
PARAMETER
Power-On Time
CONDITIONS
MIN
TYP
4
MAX
UNITS
µs
Input Capacitance
2.5
pF
f =10kHz, V
= 2V , AVCL =1, V
= 5V,
AOUT
P-P
VCC
Total Harmonic Distortion
Settling Time to 0.01%
0.01
10
%
µs
Ω
R
= 100kΩ to V
/2
VCC
AOUT
∆V
= 4V step, V
= 5V, AVCL = 1
AOUT
VCC
Active Discharge Output
Impedance
V
= 0, I
= 1mA
100
500
SHDN2
AOUT
ELECTRICAL CHARACTERISTICS (TEMPERATURE SENSOR)
(V
= V = V
= V
= 2.7V, V
= V
= V
= V
= V
= V
= 0, IN- = IN+ = AOUT = COMP = LX =
INP
IN
VCC
SHDN3
AGND
PGND
PWM
SHDN1
SHDN2
ADJ
OUT = REF = unconnected, C
= 0.01µF (min), T = 0°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.)
TOUT
A
A
PARAMETER
CONDITIONS
MIN
-3.5
-2.5
-2.5
TYP
MAX
+3.5
+2.5
+2.5
UNITS
T
T
T
= 0°C (Note 2)
= +25°C (Note 2)
= +85°C
A
A
A
Temperature Sensor Error
(Note 3)
°C
Output Voltage at +27°C
Sensor Gain (Note 4)
Nonlinearity
1.56
-11.64
0.4
V
mV/°C
%
Load Regulation
0 ≤ I
≤ 15µA
-5
-2.3
18
mV
mV/V
µA
LOAD
Line Regulation
2.6V ≤ V
2.6V ≤ V
≤ 5.5V
VCC
VCC
Quiescent Current
SHDN3 Logic High Voltage
SHDN3 Logic Low Voltage
SHDN3 Current
≤ 5.5V
< 5.5V
< 5.5V
10
2.6V < V
2.6V < V
1.6
V
VCC
VCC
0.6
1.0
V
V
= 5.5V
0.1
µA
VCC
_______________________________________________________________________________________
5
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
ELECTRICAL CHARACTERISTICS (STEP-DOWN CONVERTER)
(V
= V = V
= V
= 3.6V, V
= V
= V
= V
= V
= 0, V
= 1.25V, COMP = IN- = IN+ =
ADJ
INP
IN
VCC
SHDN1
PWM
PGND
AGND
SHDN2
SHDN3
AOUT = TOUT = unconnected, C
otherwise noted.) (Note 5)
= 0.1µF, T = -40°C to +85°C, V
for MAX1958 = 2.2V, V
for MAX1959 = 1.7V, unless
REF
A
OUT
OUT
PARAMETER
Supply Voltage Range
CONDITIONS
MIN
TYP
MAX
5.5
UNITS
2.6
V
V
Undervoltage Lockout Threshold
Rising or falling, hysteresis is 1%
PWM = AGND (MAX1958)
PWM = AGND (MAX1959)
MAX1958
2.20
2.55
300
450
550
600
6
Quiescent Current
µA
Quiescent Current in Dropout
µA
µA
MAX1959
Shutdown Supply Current
V
= 0
SHDN1
ERROR AMPLIFIER
V
V
V
V
V
V
V
V
V
V
V
V
= 1.932V, I
= 0.426V, I
= 0.426V, I
= 0 to 600mA, V
= V = 3.8V
3.36
0.739
0.739
3.570
0.98
0.98
2
3.44
0.761
0.761
3.625
1.02
1.02
6
ADJ
ADJ
ADJ
ADJ
ADJ
ADJ
OUT
OUT
OUT
OUT
ADJ
ADJ
LOAD
LOAD
LOAD
PWM
IN
OUT Voltage Accuracy
(MAX1958)
V
V
= 0 to 30mA, V
= 0 to 30mA, V
= 0
PWM
PWM
= V = 4.2V
IN
= 2.2V, I
= 0.9V, I
= 0.9V, I
= 0.75V
= 3.4V
= 0 to 600mA, V
= V = 4V
LOAD
LOAD
LOAD
PWM IN
OUT Voltage Accuracy
(MAX1959)
= 0 to 30mA, V
= 0 to 30mA, V
= 0
PWM
PWM
= V = 4.2V
IN
OUT Input Current (MAX1958)
OUT Input Current (MAX1959)
µA
µA
11
25
= 1V
2.5
6.5
= 3.6V
10.0
-150
-150
23.0
+150
+150
ADJ Input Current (MAX1958)
ADJ Input Current (MAX1959)
= 0.426V to 1.932V
= 0.9V to 2.2V
nA
nA
Positive COMP Output Current
(MAX1958)
V
V
V
V
= 1V, V
= 1V, V
= 1V, V
= 1V, V
= 1.5V, V = 1.25V
COMP
-27.0
-27.0
6.5
-6.5
-6.5
27.0
27.0
µA
µA
µA
µA
ADJ
ADJ
ADJ
ADJ
OUT
OUT
OUT
OUT
Positive COMP Output Current
(MAX1959)
=1V, V
= 1.25V
COMP
Negative COMP Output Current
(MAX1958)
= 2V, V
= 1.25V
COMP
Negative COMP Output Current
(MAX1959)
= 1.4V, V
=1.25V
6.5
COMP
REFERENCE
REF Output Voltage
REF Load Regulation
Undervoltage Lockout Threshold
Supply Rejection
1.226
0.85
1.275
6.25
1.10
1.7
V
mV
V
10µA < I
< 100µA
REF
Rising or falling, 1% hysteresis
2.6V < V < 5.5V
mV/V
IN
6
_______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
ELECTRICAL CHARACTERISTICS (STEP-DOWN CONVERTER) (continued)
(V
= V = V
= V
= 3.6V, V
= V
A
= V
= V
= V
= 0, V
= 1.25V, COMP = IN- = IN+ =
INP
IN
VCC
SHDN1
PWM
PGND
AGND
SHDN2
OUT
SHDN3
ADJ
AOUT = TOUT = unconnected, C
otherwise noted.) (Note 5)
= 0.1µF, T = -40°C to +85°C, V
for MAX1958 = 2.2V, V
for MAX1959 = 1.7V, unless
REF
OUT
PARAMETER
CONTROLLER
CONDITIONS
MIN
TYP
MAX
UNITS
I
I
I
I
= 180mA, V = 3.6V
0.4
0.5
LX
LX
LX
LX
IN
P-Channel On-Resistance
N-Channel On-Resistance
Ω
Ω
A
A
= 180mA, V = 2.6V
IN
= 180mA, V = 3.6V
0.3
IN
= 180mA, V = 2.6V
0.35
IN
P-Channel Current-Limit
Threshold
1.1
1.6
P-Channel Pulse-Skipping
Current Threshold
V
= 0
0.11
-20
0.18
PWM
LX Leakage Current
LX RMS Current
V
= 5.5V
+20
1.0
µA
A
IN
(Note 1)
Maximum Duty Cycle
Minimum Duty Cycle
Oscillator Frequency
LOGIC INPUTS (PWM, SHDN1)
Logic Input High
100
0.8
1.6
%
V
= 0
0
%
PWM
1.2
MHz
2.6V < V < 5.5V
V
V
IN
Logic Input Low
2.6V < V < 5.5V
0.6
1
IN
Logic Input Current
V
= 5.5V
µA
IN
_______________________________________________________________________________________
7
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
ELECTRICAL CHARACTERISTICS (OP AMP)
(V
= V = V
= V
= 2.7V, V
= V
/2, R = ∞ connected from AOUT to V
/2, V
= V
= V
=
SHDN1
INP
IN
= V
VCC
= V
SHDN2
AOUT
VCC
L
VCC
PGND
AGND
V
= 0, OUT = LX = TOUT = REF = COMP = unconnected, V
= 0, T = -40°C to +85°C, unless otherwise
SHDN3
PWM
ADJ
CM A
noted.) (Note 5)
PARAMETER
CONDITIONS
MIN
TYP
MAX
5.5
UNITS
Supply Voltage Range
2.6
V
V
V
V
V
V
V
= 2.6V
= 5V
800
900
2.0
VCC
VCC
µA
Supply Current
= 0, V
= 5.5V
SHDN2
VCC
Input Offset Voltage
Input Bias Current
Input Offset Current
- 0.1V ≤ V
- 0.1V ≤ V
- 0.1V ≤ V
≤ V
≤ V
≤ V
+ 0.1V
+ 0.1V
+ 0.1V
3.0
mV
nA
nA
AGND
AGND
AGND
CM
CM
CM
VCC
VCC
VCC
100
10
Input Common-Mode Voltage
V
V
VCC
+ 0.1V
AGND
V
Range, V
- 0.1V
CM
Common-Mode Rejection Ratio,
CMRR
V
- 0.1V ≤ V
≤ V
+ 0.1V
60
dB
AGND
CM
VCC
Power-Supply Rejection Ratio,
PSRR
2.6V < V
< 5.5V
70
85
dB
dB
VCC
Large-Signal Voltage Gain, AVOL
V
+ 0.20V ≤ V
≤ V - 0.20V, R = 2kΩ
VCC L
AGND
OUT
Output Voltage Swing High, VOH V
- V
, R = 2kΩ
90
90
VCC
VOH
L
Output Voltage Swing Low, VOL
V
VOL
- V
AGND
, RL = 2kΩ
mV
V
0.3 x
SHDN2 Logic Low
2.6V < V
2.6V < V
< 5.5V
VCC
V
VCC
0.7 x
SHDN2 Logic High
< 5.5V
V
VCC
V
VCC
SHDN2 Input Current
0 < V
< V
120
nA
pF
SHDN2
VCC
Capacitive-Load Stability
AVCL = 1V/V (Note 2)
470
500
Active Discharge Output
Impedance
V
= 0, I = 1mA
Ω
SHDN2
AOUT
8
_______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
ELECTRICAL CHARACTERISTICS (TEMPERATURE SENSOR)
(V
= V = V
= V
= 2.7V, V
= V
= V
= V
= V
= V
= 0, IN- = IN+ = AOUT = COMP = LX =
INP
IN
VCC
SHDN3
AGND
PGND
PWM
SHDN1
SHDN2
ADJ
OUT = REF = unconnected, C
= 0.01µF (min), T = -40°C to +85°C, unless otherwise noted.) (Note 5)
TOUT
A
PARAMETER
CONDITIONS
MIN
-7
TYP
MAX
+4
UNITS
T
T
T
= -40°C (Note 2)
= +25°C (Note 2)
= +85°C
A
A
A
Temperature Sensor Error
(Note 3)
°C
-2.5
-2.5
+2.5
+2.5
-5
Load Regulation
0 ≤ I
≤ 15µA
mV
mV/V
µA
V
LOAD
Line Regulation
2.6V ≤ V
2.6V ≤ V
≤ 5.5V
-2.3
18
VCC
VCC
Quiescent Current
SHDN3 Logic High Voltage
SHDN3 Logic Low Voltage
SHDN3 Current
≤ 5.5V
< 5.5V
< 5.5V
2.6V < V
2.6V < V
1.6
VCC
VCC
0.6
1
V
V
= 5.5V
µA
VCC
Note 2: Guaranteed by design, not production tested.
-6
2
-2
Note 3: V
= (-4 x 10 ) ✕ (T °C) - (1.13 ✕ 10 ) ✕ (T°C) + 1.8708V.
TOUT
Note 4: Linearized gain = V
= -11.64mV/°C + 1.8778V.
TOUT
Note 5: Specifications to -40°C are guaranteed by design and not subject to production test.
Typical Operating Characteristics
(T = +25°C, unless otherwise noted.)
A
EFFICIENCY vs. LOAD CURRENT
EFFICIENCY vs. LOAD CURRENT
EFFICIENCY vs. LOAD CURRENT
100
100
90
80
70
60
50
40
30
100
90
80
70
60
50
40
SKIP MODE
= 3.6V
95
V
IN
SKIP MODE
90
SKIP MODE
V
= 3.6V
IN
V
IN
= 3.6V
85
80
75
70
65
60
SKIP MODE
= 4.2V
SKIP MODE
= 4.2V
SKIP MODE
V = 4.2V
IN
PWM
= 3.6V
V
IN
V
IN
V
IN
PWM
= 3.6V
PWM
= 3.6V
V
IN
V
IN
PWM
= 4.2V
V
IN
PWM
= 4.2V
PWM
= 4.2V
V
IN
V
IN
V
= 1.5V
V
= 2.5V
V
= 3.4V
OUT
OUT
OUT
10
100
LOAD CURRENT (mA)
1000
10
100
LOAD CURRENT (mA)
1000
10
100
LOAD CURRENT (mA)
1000
_______________________________________________________________________________________
9
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
Typical Operating Characteristics (continued)
(T = +25°C, unless otherwise noted.)
A
SUPPLY CURRENT vs. INPUT VOLTAGE
SKIP MODE
DROPOUT VOLTAGE ACROSS P-CHANNEL
SUPPLY CURRENT vs. INPUT VOLTAGE
FORCED PWM
MOSFET vs. LOAD CURRENT
250
230
210
190
170
150
130
110
90
300
6
5
4
3
2
1
0
PWM = AGND
V
= 0.75V
OUT
V
= 1.5V
OUT
MAX1958
PWM = IN
MAX1958
250
200
150
100
50
70
50
0
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
0
100 200 300 400 500 600 700 800
LOAD CURRENT (mA)
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
MEDIUM-LOAD SWITCHING WAVEFORMS
(I = 300mA)
HEAVY-LOAD SWITCHING WAVEFORMS
(I = 600mA)
LOAD
LOAD
MAX1958/59 toc08
MAX1958/59 toc07
5V/div
5V/div
LX
LX
I
I
LX
LX
100mA/div
100mA/div
V
V
OUT
AC-COUPLED
OUT
AC-COUPLED
10mV/div
10mV/div
400ns/div
400ns/div
LIGHT-LOAD SWITCHING WAVEFORMS
(PWM = IN, I = 30mA)
LIGHT-LOAD SWITCHING WAVEFORMS
(PWM = AGND, I = 30mA)
LOAD
LOAD
MAX1958/59 toc09
MAX1958/59 toc10
5V/div
5V/div
LX
LX
I
I
LX
LX
100mA/div
100mA/div
V
V
OUT
AC-COUPLED
OUT
AC-COUPLED
10mV/div
10mV/div
400ns/div
400ms/div
10 ______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
Typical Operating Characteristics (continued)
(T = +25°C, unless otherwise noted.)
A
ENTERING AND EXITING SHUTDOWN
MAX1958 ADJ TRANSIENT
MAX1958/59 toc11
MAX1958/59 toc12
3.4V
5V/div
V
V
SHDN
OUT
0.75V
I
IN
50mA/div
1V/div
1.932V
0.426V
V
V
OUT
ADJ
400µs/div
10µs/div
LOAD TRANSIENT
PWM = AGND
LOAD TRANSIENT
PWM = IN
MAX1958/59 toc13
MAX1958/59 toc14
V
V
OUT
AC-COUPLED
OUT
AC-COUPLED
100mV/div
100mV/div
400mA
30mA
400mA
30mA
I
I
OUT
OUT
C
= 10µF
C
= 10µF
OUT
OUT
100µs/div
100µs/div
OP AMP SUPPLY CURRENT
vs. INPUT VOLTAGE
LOAD TRANSIENT
MAX1958/59 toc15
500
450
400
350
300
250
200
T
= +125°C
A
V
OUT
AC-COUPLED
10mV/div
T
= +85°C
= +25°C
A
T
A
4V
3V
V
IN
T
= -40°C
A
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
(V)
1ms/div
V
CC
______________________________________________________________________________________ 11
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
Typical Operating Characteristics (continued)
(T = +25°C, unless otherwise noted.)
A
OP AMP
OP AMP
INPUT OFFSET VOLTAGE
vs. COMMON-MODE VOLTAGE
INPUT OFFSET VOLTAGE
vs. COMMON-MODE VOLTAGE
600
500
400
300
200
100
0
600
500
400
300
200
100
0
T = +125°C
T = +125°C
A
A
V
= 5.5V
V
= 2.5V
VCC
VCC
T = +85°C
A
T = +85°C
A
T = +25°C
A
T = +25°C
A
T = -40°C
A
T = -40°C
A
0
0.5
1.0
1.5
2.0
2.5
0
1
2
3
4
5
6
V
CM
(V)
V
(V)
CM
OP AMP
OUTPUT SOURCE CURRENT
vs. OUTPUT VOLTAGE
OP AMP
INPUT BIAS CURRENT
vs. COMMON-MODE VOLTAGE
14
20
V
= 5.5V
VCC
V
= 5.5V
VCC
T = -40°C
A
12
10
8
15
10
5
T = +125°C
A
T = +85°C
A
V
= 2.5V
VCC
6
0
4
-5
-10
-15
2
T = +25°C
A
0
0
1
2
3
4
5
6
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
(V)
V
(V)
V
AOUT
CM
OP AMP
OP AMP
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
OUTPUT SINK CURRENT
vs. OUTPUT VOLTAGE
0
50
45
40
35
30
25
20
15
10
5
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
V
= 5.5V
= 2.5V
VCC
V
VCC
0
5.0 5.5
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
(V)
0.1
1
10
100
1k
10k
V
FREQUENCY (Hz)
AOUT
12 ______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
Typical Operating Characteristics (continued)
(T = +25°C, unless otherwise noted.)
A
OP AMP
SMALL-SIGNAL TRANSIENT
RESPONSE (NONINVERTING)
OP AMP
GAIN AND PHASE vs. FREQUENCY
MAX1958/59 toc24
MAX1958/59 toc23
80
60
90
30
2kΩ || 470pF
20mV/div
20mV/div
40
20
-30
-90
IN
PHASE
GAIN
100
0
-150
-210
-20
OUT
-40
-270
0.1
1
10
1k
10k
4µs/div
FREQUENCY (Hz)
OP AMP
OP AMP
LARGE-SIGNAL TRANSIENT
RESPONSE (NONINVERTING)
SMALL-SIGNAL TRANSIENT
RESPONSE (INVERTING)
MAX1958/59 toc26
MAX1958/59 toc25
V
= 5V
VCC
IN
2V/div
2V/div
20mV/div
IN
20mV/div
OUT
OUT
40µs/div
4µs/div
OP AMP
LARGE-SIGNAL TRANSIENT
RESPONSE (INVERTING)
TEMPERATURE SENSOR TOUT VOLTAGE
vs. TEMPERATURE
MAX1958/59 toc27
V
= 5V
VCC
2.25
IN
2V/div
2V/div
1.75
1.25
0.75
0.25
OUT
-40 -25 -10
5
20 35 50 65 80 95 110 125
40µs/div
TEMPERATURE (°C)
______________________________________________________________________________________ 13
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
Typical Operating Characteristics (continued)
(T = +25°C, unless otherwise noted.)
A
TEMPERATURE SENSOR
SUPPLY CURRENT vs. INPUT VOLTAGE
TEMPERATURE SENSOR
ERROR vs. TEMPERATURE
20
18
16
14
12
10
8
1.5
1.0
0.5
0
-0.5
-1.0
-1.5
6
4
2
0
0
1
2
3
4
5
6
-40 -25 -10
5
20 35 50 65 80 95
INPUT VOLTAGE (V)
TEMPERATURE (°C)
Pin Description
PIN
NAME
FUNCTION
Op-Amp Output. AOUT discharges to AGND during shutdown.
1
AOUT
Shutdown Control Input for the Op Amp. Drive to AGND to shut down the op amp. Connect to V
drive high for normal operation.
or
CC
2
3
SHDN2
Analog Ground. Ground for op amp, temperature sensor, and the precision circuits in the DC-to-DC
regulator. Connect to pin 6.
AGND
4
5
6
TOUT
REF
Analog Voltage Output Representing the Die Temperature. Bypass to AGND with a 0.01µF capacitor.
Internal 1.25V Reference. Bypass to AGND with a 0.1µF capacitor.
Analog Ground. Connect to pin 3.
AGND
Compensation. Typically, connect a 22pF capacitor from COMP to AGND and a 9.1kΩ resistor and
560pF capacitor in series from COMP to AGND to stabilize the regulator (see the Compensation and
Stability section).
7
8
COMP
ADJ
External Reference Input. Connect ADJ to the output of a D/A converter for dynamic adjustment of the
regulator’s output voltage. OUT regulates at (1.76 x V
) for the MAX1958 and (2 x V
- 0.8V) for
ADJ
ADJ
the MAX1959.
Shutdown Control Input for the Temperature Sensor. Drive to AGND to shut down the temperature
sensor. Connect to V or drive high for normal operation.
CC
9
SHDN3
Output Voltage Feedback. Connect OUT directly to the output. OUT is high impedance during
shutdown.
10
OUT
11
12
13
PGND
LX
Power Ground for the DC-to-DC Converter
Inductor Connection to the Internal Power MOSFETs
Low-Current Supply Voltage Input. Connect to INP at the IC.
IN
14 ______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
Pin Description (continued)
PIN
NAME
FUNCTION
High-Current Supply Voltage Input. Connect to a 2.6V to 5.5V source. Bypass to PGND with a low-
ESR 4.7µF capacitor. Connect to pin 16.
14
INP
PWM/Skip-Mode Input. Drive low to use PWM mode at medium and heavy loads and pulse-skipping
mode at light loads. Drive high to force PWM mode at all loads.
15
16
17
PWM
INP
Supply Voltage Input. Connect to pin 14.
Shutdown Control Input for the Converter. Drive to AGND to shut down the converter. Connect to IN
or drive high for normal operation.
SHDN1
18
19
20
V
Supply Input for Op Amp and Temperature-Sensor Circuitry. Connect to INP through an RC filter.
Noninverting Input for the Op Amp
CC
IN+
IN-
Inverting Input for the Op Amp
Exposed
Paddle
—
Connect to Large AGND Plane. Internally connected to AGND.
skipping operation when the peak inductor current
Detailed Description
PWM Step-Down DC-to-DC Converter
drops below 150mA. During pulse-skipping operation,
switching occurs only as necessary to service the load,
thereby reducing the switching frequency and associat-
ed losses in the internal switch, synchronous rectifier,
and inductor.
The PWM step-down DC-to-DC converter is optimized
for low-voltage, battery-powered applications where high
efficiency and small size are priorities. It is specifically
intended to power the linear HBT PA in N-CDMA/
W-CDMA handsets. An analog control signal (ADJ)
dynamically adjusts the converter’s output voltage from
0.75V to 3.4V (MAX1958) or 1V to 3.6V (MAX1959) with a
settling time of approximately 30µs. The MAX1958/
MAX1959 operate at a high 1MHz switching frequency
that reduces external component size. The IC contains
an internal synchronous rectifier that increases efficiency
and eliminates the need for an external Schottky diode.
The normal operating mode uses constant-frequency
PWM switching at medium and heavy loads and pulse
skips at light loads to reduce supply current and extend
battery life. An additional forced-PWM mode switches at
a constant frequency, regardless of load, to provide a
well-controlled noise spectrum for easier filtering in
noise-sensitive applications. The MAX1958/MAX1959
are capable of 100% duty-cycle operation to increase
efficiency in dropout. Battery life is maximized with a
0.1µA (typ) logic-controlled shutdown mode.
During pulse-skipping operation, a switching cycle initi-
ates when the error amplifier senses that the output
voltage has dropped below the regulation point. If the
output voltage is low, the high-side P-channel MOSFET
switch turns on and conducts current through the
inductor to the output filter capacitor and load. The
PMOS switch turns off when the output voltage rises
above the regulation point and the error amplifier is sat-
isfied. The MAX1958/MAX1959 then wait until the error
amplifier senses an out-of-regulation output voltage to
start the cycle again.
At peak inductor currents above 150mA, the
MAX1958/MAX1959 operate in PWM mode. During
PWM operation, the output voltage is regulated by
switching at a constant frequency and then modulating
the power transferred to the load using the error com-
parator. The error amplifier output, the main switch
current-sense signal, and the slope compensation
ramp are all summed at the PWM comparator (see the
Functional Diagram). The comparator modulates the
output power by adjusting the peak inductor current
during the first half of each cycle based on the output
error voltage. The MAX1958/MAX1959 have relatively
low AC loop gain coupled with a high-gain integrator to
enable the use of a small, low-valued output filter
capacitor. The resulting load regulation is ≤1.5% from 0
Normal-Mode Operation
Connecting PWM to GND enables PWM/pulse-skipping
operation. This proprietary control scheme uses pulse-
skipping mode at light loads to improve efficiency and
reduce quiescent current to 190µA for the MAX1958
and 280µA for the MAX1959. With PWM/pulse-skipping
mode enabled, the MAX1958/MAX1959 initiate pulse-
______________________________________________________________________________________ 15
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
to 600mA. Some jitter is normal during the transition from
pulse-skipping mode to PWM mode with loads around
75mA. This has no adverse impact on regulation.
Undervoltage Lockout (UVLO)
The DC-to-DC converter portion of the MAX1958/
MAX1959 is disabled if battery voltage on IN is below the
UVLO threshold of 2.35V (typ). LX remains high imped-
ance until the supply voltage exceeds the UVLO thresh-
old. This guarantees the integrity of the output voltage
and prevents excessive current during startup and as
the battery supply drops in voltage during use. The op
amp and temperature sensor are not connected to the
UVLO and therefore continue to operate normally.
Forced-PWM Operation
To force PWM operation at all loads, connect PWM to
IN. Forced-PWM operation is desirable in sensitive
RF and data-acquisition applications to ensure that
switching-noise harmonics are predictable and can be
easily filtered. This is to ensure that the switching noise
does not interfere with sensitive IF and data sampling
frequencies. A minimum load is not required during
forced-PWM operation because the synchronous recti-
fier passes reverse inductor current as needed to allow
constant-frequency operation with no load. Forced-
PWM operation has higher quiescent current than
pulse-skipping mode (3mA typically compared to
190µA) due to continuous switching.
Synchronous Rectification
An N-channel synchronous rectifier operates during the
second half of each switching cycle (off-time). When the
inductor current falls below the N-channel current-com-
parator threshold or when the PWM reaches the end of
the oscillator period, the synchronous rectifier turns off.
This prevents reverse current flow from the output to
the input in pulse-skipping mode. During PWM opera-
tion, small amounts of reverse current flow through the
N-channel MOSFET during light loads. This allows reg-
ulation with a constant switching frequency and elimi-
nates minimum load requirements for fixed-frequency
operation. The N-channel reverse-current comparator
threshold is -500mA. The N-channel zero-crossing
threshold in pulse-skipping mode is 20mA (see the
Forced-PWM Operation and Normal-Mode Operation
sections)
100% Duty-Cycle Operation
The maximum on-time can exceed one internal oscillator
cycle, which permits operation at 100% duty cycle. As
the input voltage drops, the duty cycle increases until
the internal P-channel MOSFET stays on continuously.
Dropout voltage at 100% duty cycle is the output cur-
rent multiplied by the sum of the internal PMOS on-
resistance (typically 0.25Ω) and the inductor
resistance. Near dropout, cycles may be skipped,
reducing switching frequency. However, voltage ripple
remains small because the current ripple is still low.
Shutdown Mode
Driving SHDN1 to ground puts the DC-to-DC converter
into shutdown mode. In shutdown mode, the reference,
control circuitry, internal-switching MOSFET, and syn-
chronous rectifier turn off and the output (LX) becomes
high impedance. Input current falls to 0.1µA (typ) dur-
ing shutdown mode. Drive SHDN1 high for normal
operation.
Dropout
Dropout occurs when the desired output regulation
voltage is higher than the input voltage minus the voltage
drops in the circuit. In this situation, the duty cycle is
100%, so the high-side P-channel MOSFET is held on
continuously and supplies current to the output up to
the current limit. The output voltage in dropout falls to
the input voltage minus the voltage drops. The largest
voltage drops occur across the inductor and high-side
MOSFET. The dropout voltage increases as the load
current increases.
Thermal Limit
The thermal limit is set at approximately +160°C and
shuts down only the converter. In this state, both main
MOSFETs are turned off. Once the IC cools by 15°C,
the converter operates normally. A continuous overload
condition results in a pulsed output. During thermal-
limit conditions, the op amp and temperature sensor
continue to operate.
During dropout, the high-side, P-channel MOSFET
turns on and the controller enters a low-current con-
sumption mode. Every 6µs (six cycles), the MAX1958/
MAX1959 check to see if the device is in dropout. The
IC remains in this mode until it is no longer in dropout.
Current-Sense Comparators
The IC uses several internal current-sense comparators.
In PWM operation, the current-sense amplifier, combined
with the PWM comparator, sets the cycle-by-cycle cur-
rent limit and provides improved load and line response.
This allows tighter specification of the inductor-saturation
current limit to reduce inductor cost. A second 150mA
current-sense comparator monitors the current through
COMP Clamp
The MAX1958/MAX1959 compensation network has a
1V to 2.25V error-regulation range. The clamp opti-
mizes transient response by preventing the voltage on
COMP from rising too high or falling too low.
16 ______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
the P-channel switch and controls entry into pulse-skip-
ping mode. A third current-sense comparator monitors
current through the internal N-channel MOSFET to pre-
vent excessive reverse currents and determines when to
turn off the synchronous rectifier. A fourth comparator
used at the P-channel MOSFET detects overcurrent. This
protects the system, external components, and internal
MOSFETs during overload conditions.
Rail-to-Rail Op Amp
The MAX1958/MAX1959 contain a rail-to-rail op amp
that can be used to provide bias for the HBT PA. As the
power needs of the PA change, the op amp can be
used to dynamically change the bias point for the PA in
order to optimize efficiency.
Figure 1. Input Protection Circuit
V
IN+
2V/div
Rail-to-Rail Input Stage
The op amp in the MAX1958/MAX1959 has rail-to-rail
input and output stages that are specifically designed
for low-voltage, single-supply operation. The input
stage consists of composite NPN and PNP differential
stages, which operate together to provide a common-
mode range extending beyond both supply rails. The
crossover region of these two pairs occurs halfway
between VCL and AGND. The input offset voltage is
typically 400µV.
V
AOUT
2V/div
Figure 2. Op-Amp Output Voltage Swing
The MAX1958/MAX1959 op amp inputs are protected
from large differential input voltages by internal 5.3kΩ
series resistors and back-to-back triple-diode stacks
across the inputs (Figure 1). For differential input volt-
ages much less than 2.1V (three diode drops), input
resistance is typically 4MΩ. For differential voltages
greater than 2.1V, input resistance is around 10.6kΩ,
and the input bias current can be approximated by the
following equation:
Rail-to-Rail Output Stage
The MAX1958/MAX1959 op amp can drive down to a
2kΩ load and still typically swing within 35mV of the
supply rails. Figure 2 shows the output voltage swing of
the MAX1958 configured with A = 1.57V/V and with
V
V
at 4.2V.
VCC
Temperature Sensor
The MAX1958/MAX1959 analog temperature sensor’s
output voltage is a linear function of its die temperature.
The slope of the output voltage is approximately
-11.64mV/°C and there is a 1.878V offset at 0°C to allow
measurement of positive temperatures. The tempera-
ture sensor functions from -40°C to +125°C .The tem-
perature error is less than 2.5°C at temperatures from
+25°C to +85°C.
(V
- 2.1V)
10.6kΩ
DIFF
I
=
BIAS
In the region where the differential input voltage
increases to about 2.1V, the input resistance decreases
exponentially from 4MΩ to 10.6kΩ as the diodes begin
to conduct. It follows that the bias current increases
with the same curve.
Nonlinearity
The benefit of silicon analog temperature sensors over
thermistors is the linearity over extended temperatures.
The nonlinearity of the MAX1958/MAX1959 is typically
0.4% over the 0°C to +85°C temperature range.
______________________________________________________________________________________ 17
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
Transfer Function
The temperature-to-voltage transfer function has an
approximately linear negative slope and can be
described by the following equation:
Compensation and Stability
The MAX1958/MAX1959 are externally compensated
with a resistor and a capacitor (R and C , Typical
C
C
Application Circuit) in series from COMP to AGND. An
additional capacitor (C ) is required from COMP to
f
AGND. The capacitor, C , integrates the current from the
C
mV
V
= −11.64
× T +1.878V
TOUT
transimpedance amplifier, averaging output capacitor
ripple. This sets the device speed for transient response
and allows the use of small ceramic output capacitors
because the phase-shifted capacitor ripple does not dis-
°C
T is the die temperature in °C. Therefore:
turb the current-regulation loop. The resistor, R , sets the
C
proportional gain of the output error voltage by a factor of
V
- 1.878V
TOUT
T =
-11.64mV/ °C
g
✕ R . Increasing this resistor also increases the sen-
C
m
sitivity of the control loop to output ripple.
To account for the small amount of curvature in the
transfer function, use the equation below to obtain a
more accurate temperature reading:
The series resistor and capacitor set a compensation
zero that defines the system’s transient response. The
load creates a dynamic pole, shifting in frequency with
changes in load. As the load decreases, the pole
frequency decreases. System stability requires that the
compensation zero must be placed to ensure adequate
phase margin (at least 30° at unity gain). The following
is a design procedure for the compensation network.
-6
2
-2
V
= (-4 ×10 × T )+ (-1.13 ×10 × T)+1.8708V
TOUT
Applications Information
PWM Step-Down DC-to-DC Converter
Select an appropriate converter bandwidth (f ) to stabi-
C
lize the system while maximizing transient response.
This bandwidth should not exceed 1/10 of the switching
frequency.
Setting the Output Voltage
The MAX1958/MAX1959 are optimized for highest sys-
tem efficiency when applying power to a linear HBT PA
in N-CDMA/W-CDMA handsets. The supply voltage to
the PA is reduced (from 3.4V to as low as 0.75V for
MAX1958) when transmitting at less than full power to
greatly conserve supply current and extend battery life.
The typical load profile for a W-CDMA PA can be seen
in Figure 3. The MAX1958/MAX1959 dramatically
reduce battery drain in these applications.
Calculate the compensation capacitor, C , based on
C
this bandwidth:
V
1
R2
R1+R2
1
OUT
OUT(MAX)
C
=
×
× g ×
m
×
C
I
R
2πf
CS
C
Resistors R1 and R2 are internal to the MAX1958/
MAX1959. For the MAX1958, use R1 = 95kΩ and R2 =
125kΩ as nominal values for calculations. For the
MAX1959, use R1 = 125kΩ and R2 = 125kΩ as nominal
The MAX1958 output voltage is dynamically adjustable
from 0.75V to 3.4V and MAX1959 output voltage is
dynamically adjustable from 1V to 3.6V using the ADJ
input. The input voltage cannot be lower than the output
values for calculations. I
is the maximum out-
m
OUT(MAX)
put current, R
= 0.5V/A, and g = 250µS. Select the
CS
voltage. V
can be adjusted during operation by dri-
OUT
closest standard value C that gives an acceptable
bandwidth.
C
ving ADJ with an external DAC. The output voltage for
the MAX1958 is determined as:
Calculate the equivalent load impedance, R , by:
L
V
=1.76× V
ADJ
OUT
V
OUT
OUT(MAX)
R =
L
The output voltage for the MAX1959 is determined as:
= 2 × V - 0.8V
I
V
OUT
ADJ
Calculate the compensation resistance (R ) to cancel
C
out the dominant pole created by the output load and
the output capacitance:
The MAX1958/MAX1959 output voltage responds to a
full-scale change in voltage and current in approxi-
mately 30µs.
1
1
=
2π × R × C
2π × R × C
C C
L
OUT
18 ______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
Solving for R gives:
C
LIR
2
I
=I
+
×I
LOAD(MAX)
PEAK LOAD(MAX)
R ×C
L
OUT
R
=
C
C
C
Input Capacitor Selection
Calculate the high-frequency compensation pole to
cancel the zero created by the output capacitor’s
equivalent series resistance (ESR):
The input capacitor (C ) reduces the current peaks
IN
drawn from the battery or input power source and
reduces switching noise in the IC. The impedance of
the input capacitor at the switching frequency should
be less than that of the input source so that high-
frequency switching currents are not required from the
source.
1
1
=
2π × R
× C
2π × R × C
C f
ESR
OUT
Solving for C gives:
f
The input capacitor must meet the ripple current
requirement (I
) imposed by the switching currents.
RMS
R
×C
Nontantalum chemistries (ceramic, aluminum, or organ-
ic) are preferred due to their resistance to power-up
ESR
OUT
Cf =
R
C
surge currents. I
is calculated as follows:
RMS
Use the calculated value for C or 22pF, whichever is
f
larger.
I
×
V
× (V - V
)
LOAD
OUT
IN OUT
I
=
RMS
Inductor Selection
There are several parameters that must be examined
when determining an optimum inductor value. Input
voltage, output voltage, load current, switching fre-
quency, and LIR. LIR is the ratio of inductor current rip-
ple to DC load current. A higher LIR value allows for a
smaller inductor, but results in higher losses and higher
output ripple current. A good compromise between
size, efficiency, and cost is an LIR of 30%. Once all the
parameters are chosen, the inductor value is deter-
mined as follows:
V
IN
Output Capacitor Selection
The output capacitor is required to keep the output
voltage ripple small and to ensure stability of the regu-
lation control loop. The output capacitor must have low
impedance at the switching frequency. An additional
constraint on the output capacitor is load transients. If it
is desired for the output voltage to swing from 0.75V to
3.4V in 30µs, the output capacitor should be approxi-
mately 4.7µF or less. Ceramic capacitors are recom-
mended. The output ripple is approximately:
V
× V - V
(
)
OUT
IN OUT
L =
1
V
× f ×I
× LIR
IN
S
LOAD(MAX)
V
= LIR × I
× ESR +
RIPPLE
LOAD(MAX)
2π × f × C
S
OUT
where f is the switching frequency (1MHz). Choose a
S
standard-value inductor close to the calculated value.
The exact inductor value is not critical and can be adjust-
ed in order to make trade-offs between size, cost, and
efficiency. Lower inductor values minimize size and cost,
but they also increase the output ripple and reduce the
efficiency due to higher peak currents. On the other
hand, higher inductor values increase efficiency, but
eventually resistive losses due to extra turns of wire
exceed the benefit gained from lower AC current levels.
For any area-restricted applications, find a low-core-loss
inductor having the lowest possible DC resistance. Ferrite
cores are often the best choice. The inductor’s saturation
current rating must exceed the expected peak inductor
See the Compensation and Stability section for a dis-
cussion of the influence of output capacitance and ESR
on regulation control-loop stability.
Rail-to-Rail Op Amp
Shutdown Mode
The MAX1958/MAX1959 op amp (Figure 4) features a
low-power shutdown mode. When SHDN2 is pulled low,
the supply current for the amplifier drops to 0.1µA, the
amplifier is disabled, and the output is actively dis-
charged to AGND with an internal 100Ω switch. Pulling
SHDN2 high enables the amplifier.
Due to the output leakage currents of three-state
devices and the small internal pullup current for
SHDN2, do not leave SHDN2 unconnected. Floating
current (I
). Consult the inductor manufacturer for sat-
PEAK
uration current ratings. Determine I
as:
PEAK
______________________________________________________________________________________ 19
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
Power-Supply Bypass
The power-supply voltage applied to V for the op
3.4
3.0
CC
amp and temperature sensor in the MAX1958/
MAX1959 circuit is filtered from INP. Connect V to
CC
INP through an RC network (R2 and C7 in Figure 4) to
ensure a quiet power supply.
Temperature Sensor
The temperature sensor provides information about the
MAX1958/MAX1959 die temperature. The voltage at
1.0
TOUT (V
) is related to die temperature as follows:
TOUT
-6
2
-2
V
= (-4 ×10 × T )+ (-1.13 ×10 × T)+1.8708V
0.4
0.0
TOUT
For stable operation, bypass TOUT to AGND with at
least a 0.01µF capacitor.
0 30
300
600
PA SUPPLY CURRENT (mA)
Temperature Sensor Error Due to Die Self-Heating
When the 800mA converter and the op amp are both
operated at heavy load while the temperature sensor is
enabled, the indicated temperature at TOUT deviates
several degrees from the actual ambient temperature
due to die self-heating effects. At light loads, when die
self-heating is low, TOUT tends to be a good approxi-
mation of the ambient temperature. At heavier loads,
the die self-heating is appreciable; TOUT gives a good
approximation of the die temperature, which can be
several degrees higher than the ambient temperature.
Figure 3. Typical W-CDMA Power Amplifier Load Profile
SHDN2 may result in indeterminate logic levels, and
could adversely affect op-amp operation.
Driving Capacitive Loads
The MAX1958/MAX1959 op amp is unity-gain stable for
capacitive loads up to 470pF. Applications that require
a greater capacitive drive capability should use an iso-
lation resistor (R
) between the output and the
ISO
capacitive load (Figure 5). Note that this alternative
results in a loss of gain accuracy because R forms a
Sensing Circuit Board and Ambient Temperature
Temperature sensors like those found in the
MAX1958/MAX1959 that sense their own die tempera-
ISO
voltage-divider with R
.
LOAD
Table 1. Recommended Inductors
RATED DC MAX
CURRENT
(mA)
DIMENSIONS
L x W x H
(mm)
INDUCTANCE
DC RESISTANCE
MANUFACTURER
PART NO.
(µH)
(mΩ)
800mA Application
Sumida
CDRH3D16-4R7
4.7
4.7
80
900
960
3.8 x 3.8 x 1.8
4.6 x 4.6 x 1.2
Toko
972AS-4R7M = P5
220
700mA Application
Sumida
CMD4D11-4R7
976AS-4R7 = P5
4.7
4.7
166
320
750
740
3.5 x 5.3 x 1.2
3.6 x 3.6 x 1.2
Toko
400mA Application
Murata
LQH3C4R7M34
CDRH2D11-4R7
4.7
4.7
200
170
450
500
2.5 x 3.2 x 2
Sumida
3.2 x 3.2 x 1.2
300mA Application
Murata
LQH1C4R7M04
4.7
650
0.34
1.6 x 3.2 x 2
Note: Efficiency may vary depending upon the inductor’s characteristics. Consult the inductor manufacturer for saturation current ratings.
20 ______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
V
IN
2.6V TO 5.5V
R6
R7
V
= V × 1+
AOUT
IN+
R2
20Ω
INP
SHDN2
MAX1958/
MAX1959
V
CC
C7
0.1µF
OFFSET
IN+
AOUT
V
REF
R6
6.8kΩ
IN-
R7
12kΩ
HBT
PA
Figure 4. Op-Amp Configuration
tures must be mounted on, or close to, the object
whose temperature they are intended to measure.
There is a good thermal path between the exposed
paddle of the package and the IC die; therefore, the
MAX1958/MAX1959 can accurately measure the
temperature of the circuit board to which they are sol-
dered. If the sensor is intended to measure the temper-
ature of a heat-generating component on the circuit
board, it should be mounted as close as possible to
that component and should share supply and ground
traces (if they are not noisy) with that component where
possible. This maximizes the heat transfer from the
component to the sensor.
MAX1958/
MAX1959
R
ISO
100Ω
AOUT
IN-
R6
R7
C
R
LOAD
LOAD
The thermal path between the plastic package and the
die is not as good as the path through the exposed
paddle, so the MAX1958/MAX1959, like all temperature
sensors in plastic packages, are less sensitive to the
temperature of the surrounding air than they are to the
temperature of its exposed paddle. They can be suc-
cessfully used to sense ambient temperature if the cir-
cuit board is designed to track the ambient
temperature.
Figure 5. Configuration for Driving Larger Capacitive Loads
The junction-to-ambient thermal resistance (θ ) is the
JA
parameter used to calculate the rise of a device junc-
tion temperature (T ) due to its power dissipation. The
J
θ
for the 20-pin QFN package is +50°C/W. For the
MAX1958/MAX1959, use the following equation to
calculate the rise in die temperature:
JA
As with any IC, the wiring and circuits must be kept
insulated and dry to avoid leakage and corrosion,
especially if the part is operated at cold temperatures
where condensation can occur.
T
= T + Θ
× P
+ P
D(OPAMP)
+ P
D(TEMPSENSOR)
J
A
JA
D(CONVERTER)
The power dissipated by the DC-to-DC converter domi-
nates in this equation. It is then reasonable to assume
______________________________________________________________________________________ 21
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
that the rise in die temperature due to the converter is a
good approximation of the total rise in die temperature.
Therefore:
Connect the inductor, input filter capacitor, and output
filter capacitor as close together as possible and keep
their traces short, direct, and wide. Connect their
ground pins at a single common node in a star ground
configuration. Keep noisy traces, such as those from
the LX pin, away from the output feedback network.
Position the bypass capacitors as close as possible to
their respective pins to minimize noise coupling. For
optimum performance, place input and output capaci-
tors as close to the device as possible. Connect AGND
and PGND to the highest quality system ground. The
MAX1958 evaluation kit illustrates an example PC
board layout and routing scheme.
T
≈ T + Θ
× P
= T + Θ
JA
× (V ×I - V )
×I
J
A
JA
D(CONVERTER)
A
IN IN OUT OUT
This equation assumes that the losses in the inductor
are relatively small. For inductors with high DC resis-
tance, inductor loss must be accounted for in the cal-
culation. The temperature rise due to power dissipation
by the converter can be quite significant.
PC Board Layout and Routing
High switching frequencies and large peak currents
make PC board layout a very important part of design.
Good design minimizes EMI, noise on the feedback
paths, and voltage gradients in the ground plane, all of
which can cause instability or regulation errors.
Optimize performance of the op amp by decreasing the
amount of stray capacitance at the op amp’s inputs
and output. Decrease stray capacitance by placing
external components as close to the device as possible
to minimize trace lengths and widths.
Typical Operating Circuit
L1
4.7µH
SUMIDA
INP
V
IN
CDRH3D16-4R7
2.6V TO 5.5V
IN
LX
C1
4.7µF
C2
4.7µF
PWM
PGND
SHDN1
OUT
R2
20Ω
AOUT
V
V
CC
REF
R6
6.8kΩ
MAX1958/
MAX1959
V
CC
IN-
C7
R7
12kΩ
0.1µF
HBT
PA
SHDN2
SHDN3
TOUT
V
TOUT
R
C
C6
0.01µF
DAC
9.1kΩ
ADJ
COMP
C
C
f
C
22pF
560pF
REF
OFFSET
C5
0.1µF
IN+
AGND
EXPOSED
PADDLE
22 ______________________________________________________________________________________
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
Functional Diagram
IN
INP
REF
1MHz
OSCILLATOR
REFERENCE
MAX1958/
MAX1959
COMP
COMP
CLAMP
ADJ
LX
ERROR
AMPLIFIER
PWM
CONTROL
SLOPE
COMPENSATION
PGND
OUT
PWM
COMPARATOR
CURRENT SENSE
SHDN1
PWM
VCC
IN+
AOUT
OP AMP
IN-
ACTIVE
DISCHARGE
SHDN2
TOUT
TEMPERATURE
SENSOR
AGND
AGND
SHDN3
Chip Information
TRANSISTOR COUNT: 3704
PROCESS: BiCMOS
______________________________________________________________________________________ 23
W-CDMA/N-CDMA Cellular Phone HBT PA
Management ICs
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
D2
0.15
C A
D
b
0.10 M
C A B
C
L
D2/2
D/2
k
PIN # 1
I.D.
0.15
C
B
PIN # 1 I.D.
0.35x45
E/2
E2/2
C
(NE-1) X
e
L
E2
E
k
L
DETAIL A
e
(ND-1) X
e
C
C
L
L
L
L
e
e
0.10
C
A
0.08
C
C
A3
A1
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE
16, 20, 28, 32L, QFN THIN, 5x5x0.8 mm
APPROVAL
DOCUMENT CONTROL NO.
REV.
1
21-0140
C
2
COMMON DIMENSIONS
EXPOSED PAD VARIATIONS
NOTES:
1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994.
2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES.
3. N IS THE TOTAL NUMBER OF TERMINALS.
4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1
SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE
ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE.
5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.25 mm AND 0.30 mm
FROM TERMINAL TIP.
6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY.
7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION.
8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS.
9. DRAWING CONFORMS TO JEDEC MO220.
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE
10. WARPAGE SHALL NOT EXCEED 0.10 mm.
16, 20, 28, 32L, QFN THIN, 5x5x0.8 mm
APPROVAL
DOCUMENT CONTROL NO.
REV.
2
21-0140
C
2
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
24 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2002 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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